P Jeffrey Conn
Vanderbilt University
Project start date: 2001-02-15
Project end date: 2016-01-31
Sponsored Links Excellgen http://Excellgen.com
REGULATION OF SIGNALING BY MGLUR5
P Jeffrey Conn, Professor
Vanderbilt University Medical Center Nashville, Tn 372036869
Grant 5R01MH062646-06 from National Institute Of Mental Health IRG: ZRG1
Abstract: DESCRIPTION(Adapted from applicant s ) The hippocampus is a limbic cortical structure that plays an important role in learning and memory, and is a primary site of temporal lobe epilepsy and Alzheimer s disease. Glutamate is the primary neurotransmitter at excitatory synapses in the hippocampus, where it acts on both ionotropic and metabotropic glutamate receptors (mGluRs). Particular attention has been focused on the NMDA subtype of glutamate receptor because of its unique role in certain forms of learning, memory, and pathological conditions including epileptic responses and excitotoxicity. Interestingly, recent studies reveal that activation of one mGluR subtype, mGluR5, can dramatically potentiate currents through NMDA receptor channels in hippocampal neurons. Furthermore, low concentrations of NMDA potentiate responses to mGluR5 activation. This positive feedback regulation between mGluR5 and NMDA receptors could play a critical role in signal amplification and may be important for NMDA receptor function. Consistent with this, several previous studies suggest that mGluR5 plays an important role in several receptor-dependent forms of synaptic plasticity and could contribute to pathological responses to NMDA receptor activation. Previous studies reveal that mGluR5 is desensitized by activation of protein kinase C (PKC) which directly phosphorylates the receptor. We recently found that mild activation of NMDA receptors-with low concentrations of NMDA-potentiates mGluR5-mediated responses by reversing this agonist-induced desensitization. Interestingly, stronger activation of NMDA receptors reduced mGluR5-mediated responses and increased mGluR5 phosphorylation. This is especially interesting in light of recent studies that suggest that low frequency stimulation of glutamatergic afferents to hippocampal area CA1 induces preferential activation of the protein phosphatase calcineuron whereas high frequency stimulation leads to activation of PKC and a net increase in protein phosphorylation. Based on this and a number of other previous studies, we postulated that the differential effects of different concentrations of NMDA on mGluR5 are mediated by net increases and decreases in mGluR5 phosphorylation. Furthermore, we postulate that low frequency stimulation of glutamatergic afferents induces preferential dephosphorylation of mGluR5 and potentiates mGluR5-mediated responses whereas high frequency stimulation induces a net increase in mGluR5 phosphorylation and inhibition of mGluR5-mediated responses. A combination of molecular, biochemical and electrophysiological techniques will be used to directly test these hypotheses.
Keywords: NMDA receptor, biological signal transduction, glutamate receptor, neural transmission, phosphorylation, receptor expression, calcium flux, hippocampus, long term potentiation, motor neuron, neural plasticity, phosphatase inhibitor, protein kinase C, Xenopus oocyte, electrophysiology, gene targeting, genetically modified animal, laboratory mouse, tissue /cell culture, voltage /patch clamp
Project start date: 2001-02-15
Project end date: 2006-01-31
5R01MH062646-06 (2005): $302000
5R01MH062646-05 (2004): $302000
5R01MH062646-11 (2010): $316729
5R01MH062646-08 (2007): $316299
Grants awarded to P Jeffrey Conn
Metabotropic Glutamate Receptors In Basal Ganglia
P Jeffrey Conn, Professor
Vanderbilt University Medical Center Nashville, Tn 372036869
Grant 5R01NS048334-03 from National Institute Of Neurological Disorders And Stroke IRG: CNNT
Abstract: Traditional therapies for treatment of Parkinson s disease (PD) based on dopamine replacement strategies eventually fail in most patients due to serious adverse effects and loss of efficacy with disease progression. Because of this, a great deal of effort has been focused on developing a detailed understanding of the circuitry and function of the basal ganglia in hopes of developing novel therapeutic approaches for restoring normal basal ganglia function in patients suffering from PD. Exciting advances in our understanding of the function of metabotropic glutamate receptors (mGluRs) and the distribution of mGluR subtypes in the basal ganglia suggest that members of this receptor family could serve as targets for novel therapeutic agents that would be effective in treatment of PD. We have performed a number of studies that suggest that the mGlu4 receptor subtype may be particularly attractive as a novel target for treatment of PD. mGlu4 is localized on presynaptic terminals in the synapse between the striatum an the globus pallidus (the striato-pallidal synapse). This is a critical synapse in the basal ganglia motor circuit and previous studies suggest that reduction of transmission at this synapse could have a therapeutic effect in PD patients. We have shown that activation of mGlu4 reduces transmission at the striato-GP synapse. Furthermore, we present data suggesting that agonists of mGlu4 may have an antiparkinsonian effect in several rodent models of PD. While these results are encouraging, it has been extremely difficult to develop selective agonists with high affinity for specific mGlu receptor subtypes that also have appropriate drug-like properties. We have exciting preliminary studies that provide a novel approach to developing small molecules that activate mGlu4. We have discovered a novel compound termed PHCCC that does not activate mGlu4 directly but dramatically potentiates activation of the receptor by glutamate or L-AP4. Furthermore, our preliminary studies suggest that allosteric potentiator of mGlu4 may have antiparkinsonian actions similar to those observed with traditional mGlu4 agonists. In the proposed studies we will rigorously test the hypothesis that mGlu4 is localized on critical striatal terminals and that activation of this receptor selectively reduces transmission at the Striatopallidal synapse. Furthermore, we will test the hypothesis that agonists or allosteric potentiators of this receptor can provide palliative relief in rodent models of PD by actions in the GP.
Keywords: Parkinson s disease, antiparkinson drug, basal ganglia, drug design /synthesis /production, glutamate receptor, stimulant /agonist, glutamate, lenticular nucleus, neural transmission, neuropharmacology, protein localization, receptor expression, small molecule, synapse, behavior test, electrophysiology, immunoelectron microscopy, laboratory mouse, laboratory rat, male
Project start date: 2004-12-05
Project end date: 2009-11-30
5R01NS048334-03 (2007): $306938
MGluR4 Potentiators As A Treatment For Parkinson s Disease
P Jeffrey Conn, Professor
Vanderbilt University Medical Center Nashville, Tn 372036869
Grant 5R21NS051342-02 from National Institute Of Neurological Disorders And Stroke IRG: NSD
Abstract: Traditional therapies for treatment of Parkinson s disease (PD) based on dopamine replacement strategies eventually fail in most patients due to serious adverse effects and loss of efficacy with disease progression. Because of this, a great deal of effort has been focused on developing a detailed understanding of the circuitry and function of the basal ganglia in hopes of developing novel therapeutic approaches for restoring normal basal ganglia function in patients suffering from PD. Exciting advances in our understanding of the function of metabotropic glutamate receptors (mGluRs) and the distribution of mGluR subtypes in the basal ganglia suggest that members of this receptor family could serve as targets for novel therapeutic agents that would be effective in treatment of PD. We have performed a number of studies that suggest that the mGluR4 receptor subtype may be particularly attractive as a novel target for treatment of PD. We have shown that activation of mGluR4 reduces transmission at the synapse between the striatum and the globus pallidus (the striato-pallidal synapse). This is a critical synapse in the basal ganglia motor circuit and previous studies suggest that reduction of transmission at this synapse could provide a therapeutic benefit to PD patients. Consistent with this, we found that agonists of mGluR4 have an antiparkinsonian effect in several rodent models of PD. While these results are encouraging, it has been extremely difficult to develop selective agonists with high affinity for specific mGluR subtypes that also have appropriate drug-like properties. We have exciting preliminary studies that provide a novel approach to developing small molecules that activate mGluR4. We have discovered a novel compound termed PHCCC that does not activate mGluR4 directly but dramatically potentiates activation of the receptor by glutamate or L-AP4. Furthermore, our preliminary studies suggest that an allosteric potentiator of mGluR4 has antiparkinsonian actions similar to those observed with traditional mGluR4 agonists. In the proposed studies we will screen a library of >150,000 compounds that were selected based on maximal diversity and chemical properties for novel molecules that act as allosteric potentiators of mGluR4. In addition, we will perform a series of rigorous secondary and tertiary assays will be performed to determine selectivity, potency, and cytotoxicity of hits from the primary screen. This high throughput screen will provide the basis for future studies aimed at developing allosteric potentiators of mGluR4 that are suitable for clinical testing.
Keywords: Parkinson s disease, basal ganglia, synapse, Primate, base, blood brain barrier, brain, calcium flux, chemical, concept, cytotoxicity, dopamine, family, fluorescence, glutamate receptor, high throughput technology, intracellular, lenticular nucleus, library, model, motivation, neuron, receptor, receptor expression, reduction, small molecule, substantia nigra, therapy
Project start date: 2006-01-01
Project end date: 2007-12-31
5R21NS051342-02 (2007): $167407
1R21NS051342-01A1 (2006): $171563
Metabotropic Glutamate Receptors In Basal Ganglia
P Jeffrey Conn, Professor
Vanderbilt University Medical Center Nashville, Tn 372036869
Grant 5R01NS048334-02 from National Institute Of Neurological Disorders And Stroke IRG: CNNT
Abstract: Traditional therapies for treatment of Parkinson s disease (PD) based on dopamine replacement strategies eventually fail in most patients due to serious adverse effects and loss of efficacy with disease progression. Because of this, a great deal of effort has been focused on developing a detailed understanding of the circuitry and function of the basal ganglia in hopes of developing novel therapeutic approaches for restoring normal basal ganglia function in patients suffering from PD. Exciting advances in our understanding of the function of metabotropic glutamate receptors (mGluRs) and the distribution of mGluR subtypes in the basal ganglia suggest that members of this receptor family could serve as targets for novel therapeutic agents that would be effective in treatment of PD. We have performed a number of studies that suggest that the mGlu4 receptor subtype may be particularly attractive as a novel target for treatment of PD. mGlu4 is localized on presynaptic terminals in the synapse between the striatum an the globus pallidus (the striato-pallidal synapse). This is a critical synapse in the basal ganglia motor circuit and previous studies suggest that reduction of transmission at this synapse could have a therapeutic effect in PD patients. We have shown that activation of mGlu4 reduces transmission at the striato-GP synapse. Furthermore, we present data suggesting that agonists of mGlu4 may have an antiparkinsonian effect in several rodent models of PD. While these results are encouraging, it has been extremely difficult to develop selective agonists with high affinity for specific mGlu receptor subtypes that also have appropriate drug-like properties. We have exciting preliminary studies that provide a novel approach to developing small molecules that activate mGlu4. We have discovered a novel compound termed PHCCC that does not activate mGlu4 directly but dramatically potentiates activation of the receptor by glutamate or L-AP4. Furthermore, our preliminary studies suggest that allosteric potentiator of mGlu4 may have antiparkinsonian actions similar to those observed with traditional mGlu4 agonists. In the proposed studies we will rigorously test the hypothesis that mGlu4 is localized on critical striatal terminals and that activation of this receptor selectively reduces transmission at the Striatopallidal synapse. Furthermore, we will test the hypothesis that agonists or allosteric potentiators of this receptor can provide palliative relief in rodent models of PD by actions in the GP.
Keywords: Parkinson s disease, antiparkinson drug, basal ganglia, drug design /synthesis /production, glutamate receptor, stimulant /agonist, glutamate, lenticular nucleus, neural transmission, neuropharmacology, protein localization, receptor expression, small molecule, synapse, behavior test, electrophysiology, immunoelectron microscopy, laboratory mouse, laboratory rat, male
Project start date: 2004-12-05
Project end date: 2009-11-30
5R01NS048334-02 (2006): $316567
1R01NS048334-01A1 (2005): $331746
Throughput Assay:Allosteric Potentiator Of GluR (RMI)
P Jeffrey Conn, Professor
Vanderbilt University Medical Center Nashville, Tn 372036869
Grant 1R03NS050851-01 from National Institute Of Neurological Disorders And Stroke IRG: ZNS1
Abstract: Traditional therapies for treatment of Parkinson s disease (PD) based on dopamine replacement strategies eventually fail in most patients due to serious adverse effects and loss of efficacy with disease progression. Because of this, a great deal of effort has been focused on developing a detailed understanding of the circuitry and function of the basal ganglia in hopes of developing novel therapeutic approaches for restoring normal basal ganglia function in patients suffering from PD. Exciting advances in our understanding of the function of metabotropic glutamate receptors (mGluRs) and the distribution of mGluR subtypes in the basal ganglia suggest that members of this receptor family could serve as targets for novel therapeutic agents that would be effective in treatment of PD. We have performed a number of studies that suggest that the mGlu4 receptor subtype may be particularly attractive as a novel target for treatment of PD. We have shown that activation of mGlu4 reduces transmission at the synapse between the striatum and the globus pallidus (the striato-pallidal synapse). This is a critical synapse in the basal ganglia motor circuit and previous studies suggest that reduction of transmission at this synapse could have a therapeutic effect in PD patients. Consistent with this, we found that agonists of mGlu4may have an anti-parkinsonian effect in several rodent models of PD. While these results are encouraging, it has been extremely difficult to develop selective agonists with high affinity for specific mGlu receptor subtypes that also have appropriate drug-like properties. We have exciting preliminary studies that provide a novel approach to developing small molecules that activate mGlu4. We have discovered a novel compound termed PHCCC that does not activate mGlu4 directly but dramatically potentiates activation of the receptor by glutamate or L-AP4. Furthermore, our preliminary studies suggest that allosteric potentiator of mGlu4 has anti-parkinsonian actions similar to those observed with traditional mGlu4 agonists. In the proposed studies we will establish a fluorescence-based assay that is suitable for use in high throughput screens for novel compounds that act as allosteric potentiators of mGlu4. We will rigorously test the utility of this assay for use in high throughput screens by running a screen of approximately 10,000 compounds that have been selected using chemical informatics approaches based on structural similarity to other allosteric regulators of mGluRs. This will provide the characterization needed to allow us to optimize this assay for use in future screens of larger compound libraries.
Keywords: Parkinson s disease, drug discovery /isolation, glutamate receptor, high throughput technology, neurotransmitter agonist, receptor expression, technology /technique development, basal ganglia, brain disorder chemotherapy, calcium flux, pharmacokinetics, small molecule, biotechnology, chemical registry /resource, cheminformatics
Project start date: 2004-09-30
Project end date: 2005-08-31
1R03NS050851-01 (2004): $75500
RECRUITMENT OF IN VIVO NEUROPHARMACOLOGIST TO SUPPORT CNS DRUG DISCOVERY RESEARCH
P Jeffrey Conn
Vanderbilt University, Medical Center, Nashville, Tn 37203-6869
Grant 5P30MH089870-02 from National Institute Of Mental Health
Abstract: The Vanderbilt Program in Drug Discovery (VPDD) is a world class effort fully focused on discovery and characterization of novel molecules to evaluate new potential treatment strategies for CNS disorders. The VPDD has had tremendous success in discovery of multiple ligands for CNS neurotransmitter receptors, ion channels, and other signaling proteins. This provides an exciting opportunity to realize unprecedented advances in understanding of the impact of manipulating these signaling pathways on animal behavior and the potential therapeutic utility of drugs acting on these systems. However, it is critical that molecules generated from this and similar academic drug discovery efforts are fully characterized in terms of pharmacokinetic properties and brain penetration before using novel molecules for in vivo studies. Thus, in vivo neuropharmacologists working with newly discovered compounds must seamlessly incorporate studies of drug disposition into their work. VPDD has established state of the art facilities for animal dosing, plasma and csf collection, and analytical chemistry required for detailed pharmacokinetic studies of novel compounds in animal models. In addition both the VPDD and Vanderbilt´s Center for Molecular Neuroscience (CMN) have established outstanding facilities for use in behavioral and other in vivo studies in rodent models. This provides the opportunity to move beyond cellular and molecular studies that drive many of the current VPDD efforts and focus on gaining new insights into in vivo effects of manipulating specific neurotransmitter systems and signaling pathways. However, to take advantage of this unique opportunity, it will be critical to recruit faculty who have strong in vivo pharmacology expertise and who have the skills required to combine behavioral pharmacology with studies of drug disposition and CNS exposure of novel compounds. We now seek funding through the NIH to support recruitment of an outstanding in vivo neuropharmacologist to a tenure track faculty position in VPDD and Department of Pharmacology, we propose a strong development package to the new faculty recruit and provide a clear plan to work with new recruit to through faculty mentoring, collaborative research opportunities, and other support needed to allow the new recruit to establish an independent career and leadership position in neuropharmacology. We propose recruitment of an outstanding in vivo neuropharmacologist to a tenure track faculty position in the Vanderbilt Program in Drug Discovery and the Vanderbilt Department of Pharmacology. Working within the context of the VPDD, provides a unique opportunity for an in vivo neuropharmacologist to achieve unprecedented advances in understanding of the impact of manipulating specific signaling pathways on animal behavior and the potential therapeutic utility of drugs acting on these systems. Using support from this grant, we will provide strong development package, focused faculty mentoring, collaborative research opportunities, and other support needed to help the new recruit to establish an independent career and leadership position in neuropharmacology
Project start date: 2009-09-30
Project end date: 2011-08-31
Budget start date: 1-SEP-2010
Budget end date: 31-AUG-2011
PFA/PA: RFA-OD-09-005
5P30MH089870-02 (2010): $737217
1P30MH089870-01 (2009): $703500
FUNCTIONS OF METABOTROPIC GLUTAMATE RECEPTOR SUBTYPES
P Jeffrey Conn, Professor
Vanderbilt University, Medical Center, Nashville, Tn 37203-6869
Grant 2R01NS031373-16A2 from National Institute Of Neurological Disorders And Stroke
Abstract: The metabotropic glutamate receptors (mGluRs) play critical roles in regulating transmission in the hippocampal formation and these actions are important for both acute regulation of hippocampal function and long-lasting forms of synaptic plasticity that may underlie hippocampal-dependent learning and memory. The mGluR5 subtype of mGluR regulates NMDA receptor currents and both long-term potentiation (LTP) and long- term depression (LTD) of transmission in hippocampal area CA1. We have shown that highly selective positive allosteric modulators (PAMs) of mGluR5 enhance both hippocampal LTP and LTD and maintain a strict dependence of both forms of hippocampal synaptic plasticity on specific patterns of activity of presynaptic afferents. This provides an excellent profile for potential cognition-enhancing agents. Exciting progress in developing systemically active mGluR5 PAMs that cross the blood brain barrier makes it possible to rigorously test the hypothesis that selective potentiation of mGluR5 signaling in vivo will enhance hippocampal-dependent forms of learning and memory. In addition to a role of mGluR5 in regulating hippocampal function, we have shown that another group of mGluRs, termed group II mGluRs (mGluR2 and mGluR3), participate in a novel form of glial-neuronal communication in the hippocampus in which activation of mGluRs on astrocytes leads to release of adenosine and reduction of glutamate release from neighboring glutamate synapses. We postulate that this astrocytic response is mediated by the mGluR3 subtype and that activation of mGluR3 could have effects on hippocampal synaptic plasticity that are opposite to those of mGluR5. If so, mGluR3 activation could impair hippocampal LTP and selective antagonists of mGluR3 could have cognition-enhancing effects. We will perform a series of studies to test the hypothesis that mGluR5 PAMs enhance hippocampal-dependent cognitive function and reverse learning deficits in genetically altered mice in which glutamatergic transmission is impaired by selective reductions in expression of the NMDA subtype of glutamate receptor. In addition, we will test the hypothesis that mGluR3 is responsible for this novel form of astrocytic-neuronal communication and that antagonists of mGluR3 can enhance synaptic transmission in the hippocampus and enhance hippocampal-dependent LTP. A family of neurotransmitter receptors called metabotropic glutamate receptors (mGluRs) have emerged as exciting new drug targets for development of medicines for treatment of a variety of psychiatric and neurological disorders, including Alzheimer´s disease, autistic disorders, and schizophrenia. We have discovered new drug like molecules that selectively interact with these receptors. Studies are proposed to determine the effects of these novel molecules in brain circuits that may be critically involved in treatment of these brain disorders
Keywords: Acute; Address; Adenosine; Adenosine A1 Receptor; Agonist; Alzheimer; Alzheimer disease; Alzheimer sclerosis; Alzheimer syndrome; Alzheimer`s; Alzheimer`s Disease; Alzheimers Dementia; Alzheimers disease; Ammon Horn; Animal Model; Animal Models and Related Studies; Area; Astrocytes; Astrocytus; Astroglia; Autism; Autism, Early Infantile; Autism, Infantile; Autistic Disorder; Behavioral; Blood - brain barrier anatomy; Blood-Brain Barrier; Brain; Brain Diseases; Brain Disorders; CNS Diseases; CNS disorder; Cell Communication and Signaling; Cell Signaling; Central Nervous System Diseases; Central Nervous System Disorders; Chemosensitization; Chemosensitization/Potentiation; Cognition; Communication; Cornu Ammonis; Coupled; Dementia, Alzheimer Type; Dementia, Primary Senile Degenerative; Dementia, Senile; Dependence; Depression; Development; Drug Delivery; Drug Delivery Systems; Drug Targeting; Drug Targetings; Drugs; Encephalon; Encephalon Diseases; Encephalons; Family; Funding; G-Proteins; GTP-Binding Proteins; GTP-Regulatory Proteins; Genetic; GluRzeta1; Glutamate Receptor; Glutamates; Goals; Guanine Nucleotide Coupling Protein; Guanine Nucleotide Regulatory Proteins; Hemato-Encephalic Barrier; Hippocampal Formation; Hippocampus; Hippocampus (Brain); Impairment; Individual; Intracellular Communication and Signaling; Intracranial CNS Disorders; Intracranial Central Nervous System Disorders; Kanner`s Syndrome; L-Glutamate; Learning; Ligands; Long-Term Depression (Neurophysiology); Long-Term Depression (Physiology); Long-Term Potentiation; Long-Term Synaptic Depression; Mammals, Mice; Mediating; Medication; Medicine; Memory; Mental Depression; Metabotropic Glutamate Receptors; Mice; Modeling; Murine; Mus; N Methyl D aspartic Acid; N methyl D aspartate; N-Methyl-D-Aspartate Receptors; N-Methyl-D-aspartate; N-Methylaspartate; NMDA; NMDA Receptor-Ionophore Complex; NMDA Receptors; NMDA receptor, NR1 subunit; NR1 NMDA receptor; NR1 protein, NMDA receptor; Nerve Cells; Nerve Unit; Nervous System Diseases; Nervous System, Brain; Neural Cell; Neural Transmission; Neurocyte; Neurologic Disorders; Neurological Disorders; Neuromediator Receptors; Neurons; Neuroregulator Receptors; Neurotransmitter Receptor; Pattern; Performance; Pharmaceutic Preparations; Pharmaceutical Preparations; Physiologic; Physiological; Play; Potentiation; Primary Senile Degenerative Dementia; Pyramidal Cells; Reagent; Receptor Protein; Receptors, N-Methylaspartate; Receptors, Neurohumor; Regulation; Rodent Model; Role; Schizophrenia; Schizophrenic Disorders; Science of Medicine; Series; Signal Transduction; Signal Transduction Systems; Signaling; Synapses; Synaptic; Synaptic Transmission; Synaptic plasticity; Testing; Therapeutic Agents; Transmission; base; beta-adrenergic receptor; biological signal transduction; cognitive function; dementia of the Alzheimer type; dementia praecox; drug/agent; glutamate receptor zeta1; hippocampal; in vivo; long term depression; mGluR2; mGluR3; metabotropic glutamate receptor 2; metabotropic glutamate receptor 3; model organism; mouse model; nervous system disorder; neurological disease; neuronal; new approaches; novel; novel approaches; novel strategies; novel strategy; presynaptic; primary degenerative dementia; public health relevance; receptor; receptor expression; receptor function; response; schizophrenic; senile dementia of the Alzheimer type; social role; tool; transmission process
Relevance: A family of neurotransmitter receptors called metabotropic glutamate receptors (mGluRs) have emerged as exciting new drug targets for development of medicines for treatment of a variety of psychiatric and neurological disorders, including Alzheimer´s disease, autistic disorders, and schizophrenia. We have discovered new drug like molecules that selectively interact with these receptors. Studies are proposed to determine the effects of these novel molecules in brain circuits that may be critically involved in treatment of these brain disorders
Project start date: 1993-08-01
Project end date: 2014-04-30
Budget start date: 15-JUL-2010
Budget end date: 30-APR-2011
PFA/PA: PA-07-070
2R01NS031373-16A2 (2010): $339063
NEUROMODULATORY ROLES OF MUSCARINIC RECEPTOR SUBTYPES
P Jeffrey Conn, Professor
Emory University 1599 Clifton Road, 4th Floor Atlanta, Ga 30322
Grant 5R01NS034876-05 from National Institute Of Neurological Disorders And Stroke IRG: NLS
Abstract: The hippocampus plays an important role in learning and memory and is a primary site of pathology in Alzheimer s disease (AD). A large number of animal and human studies suggest that projections of acetylcholine (ACh)-containing neurons to the hippocampus are critical for memory and attentional mechanisms and the degeneration of these neurons plays a critical role in dementia associated with AD. Furthermore, a compound that inhibits Ach metabolism, termed tacrine, is the only approved treatment for AD. However, this compound suffers from low efficacy and a high incidence of side effects. Development of drugs that mimic the actions of Ach by acting as direct agonists of the specific muscarinic acetylcholine receptors (mAChRs) involved in regulating hippocampal physiology could overcome the limitations of tacrine and provide highly efficacious agents for treatment of AD. However, the specific mAChR subtypes that mediate each of the major actions of Ach in the hippocampus are unknown. A series of studies is proposed in which a combination of biophysical, molecular, and pharmacological approaches will be used to determine which of the five MAChR subtypes (m1 - m5) mediate each of the major physiological effects of mAChR activation in the hippocampal formation. Previous studies led us to postulate that 1) m1 mediates mAChR-induced potentiation of NMDA-evoked currents in hippocampal area CA1; 2)reduction of excitatory synaptic transmission is mediated by m4 receptors presynaptically localized on glutamatergic terminals; and 3) m2 mediates MAChR-induced disinhibition by reducing GABA release. In the studies with subtype-specific mAChR toxins, mAChR subtype-specific antibodies, recently developed pharmacological reagents, and antisense oligonucleotides to test these hypotheses. In aim 4 we will use the same approaches to determine which mAChR subtypes mediate the direct excitatory effects of mAChR activation on CA1 pyramidal cells. mAChR activation increases excitability of hippocampal pyramidal cells by reducing three potassium currents. Thus, voltage clamp techniques will be used with mAChR subtype-selective tools to determine which mAChR subtype mediates mAChR-induced modulation of each of these currents.. These studies will provide significant advance in our understanding of the roles of ACh in agonists that can be used for treatment of AD and related disorders.
Keywords: hippocampus, muscarinic receptor, neuropharmacology, receptor expression, G protein, NMDA receptor, calcium flux, glutamate, neural transmission, prosencephalon, protein isoform, receptor coupling, reptile poison, synapse, Animalia, immunoprecipitation, tissue /cell culture
Project start date: 1996-02-01
Project end date: 2001-01-31
5R01NS034876-05 (2000): $176750
Sponsored Links Excellgen http://Excellgen.com
5R01NS034876-04 (1999): $170415
5R01NS034876-03 (1998): $164326
5R01NS034876-02 (1997): $158472
FUNCTIONS OF METABOTROPIC GLUTAMATE RECEPTOR SUBTYPES
P Jeffrey Conn, Professor
Emory University 1599 Clifton Road, 4th Floor Atlanta, Ga 30322
Grant 5R01NS031373-03 from National Institute Of Neurological Disorders And Stroke IRG: NLS
Abstract: The hippocampus plays an important role in a number of normal physiological processes and in pathological conditions, including Alzheimer s disease and epilepsy. Development of a complete understanding of the molecular and cellular mechanisms of regulation of synaptic function in the hippocampus could lead to new Strategies for treatment of these disorders. Until recently, it was thought that most neuro- modulatory influences on hippocampal function required activation of extrinsic afferents and that all of the actions of glutamate, the major neurotransmitter intrinsic to the hippocampus, were mediated by activation of ligandgated cation channels. However, it is now clear that glutamate also activates receptors, known as metabotropic glutamate receptors (mGluRs), that are coupled to effector systems through GTP binding proteins. To date, 5 mGluR subtypes have been cloned. However, the precise roles of the different mGluR subtypes in regulating neuronal excitability and synaptic transmission in the hippocampus are not known. A complete understanding of both normal and pathological hippocampal function will require a detailed understanding of the roles of mGluRs in regulating hippocampal physiology. Interestingly, application of IS,3R- ACPD (a selective mGluR agonist) to hippocampal slices, potentiates cyclic AMP responses to agonists of other receptors that are positively coupled to adenylate cyclase. Also, IS,3R-ACPD has a number of important physiological effects in the hippocampus. These include, among others, a decrease in synaptic -inhibition in hippocampal area CA1 and a decrease in evoked population spikes in the dentate gyrus. However, the precise cellular and synaptic mechanisms by which mGluR agonists modulate inhibitory and excitatory synaptic responses in the hippocampus are not known. Furthermore, the physiological relevance of 1S,3R-ACPD-induced potentiation of cyclic AMP responses is not known. A series of experiments is proposed in which microelectrode and patch clamp recordings from hippocampal neurons will be used to test the hypothesis that 1S,3R-ACPD decreases synaptic inhibition in area CA1 and evoked population spikes in dentate gyrus by reducing excitatory transmission onto inhibitory interneurons and dentate granule cells, respectively. Also, experiments will be performed to determine the physiological role of mGluR-mediated potentiation of cyclic AMP responses in regulating synaptic transmission in the hippocampus. Finally, specific antibodies will be raised against each of the cloned mGluR subtypes. These will be used to determine the precise cellular and subcellular localization of the different mGluR subtypes in the hippocampal formation. These studies, coupled with the electrophysiological experiments, will provide valuable information regarding the roles of specific mGluR subtypes in regulating hippocampal function.
Keywords: dentate gyrus, excitatory aminoacid, glutamate receptor, neural inhibition, synapse, adenylate cyclase, entorhinal cortex, enzyme activity, granule cell, interneuron, isoproterenol, lipolysis, membrane potential, neurotransmitter transport, oligopeptide, phosphatidylcholine, CHO cell, antireceptor antibody, epitope mapping, immunocytochemistry, laboratory rabbit, laboratory rat, patch clamp
Project start date: 1993-08-01
Project end date: 1996-07-31
5R01NS031373-03 (1995): $138722
5R01NS031373-02 (1994): $144762
5R01NS031373-09 (2001): $342188
2R01NS031373-08 (2000): $344344
5R01NS031373-07 (1999): $254546
5R01NS031373-06 (1998): $245222
5R01NS031373-05 (1997): $236257
Sponsored Links Excellgen http://Excellgen.com
5R01NS031373-14 (2007): $336209
5R01NS031373-13 (2006): $344745
2R01NS031373-12A1 (2005): $350729
5R01NS031373-15 (2008): $0
MUSCARINIC RECEPTOR ACTIVATORS AS NOVEL ANTIPSYCHOTIC AGENTS
P Jeffrey Conn, Professor
Vanderbilt University, Medical Center, Nashville, Tn 37203-6869
Grant 5R01MH073676-05 from National Institute Of Mental Health
Abstract: Recent clinical studies reveal that agents that activate muscarinic acetylcholine receptors (mAChRs) have robust efficacy in reducing psychotic symptoms in patients with schizophrenia as well as AD and other neurodegenerative disorders. Evidence suggests that the antipsychotic effects of cholinergic agents may be mediated by the M1 mAChR subtype. However, previous compounds developed to selectively activate M1 receptors lack true specificity for M1. This has resulted in problems with adverse effects due to M2 and M3 activation in patients and has made it impossible to definitively determine whether the behavioral and clinical effects of these compounds are mediated by M1 or other mAChR subtypes. Despite major efforts by multiple industry and academic laboratories, it has been impossible to develop clinically useful highly selective M1 agonists that act the orthosteric acetylcholine (ACh) binding site. This is likely due to the high degree of conservation of the ACh site between mAChR subtypes. In recent years we have been highly successful in establishing a new class of compounds that act as allosteric potentiators of G protein-coupled receptors that may provide key advantages to direct-acting agonists. Unlike agonists, these compounds do not directly activate the receptor but act at an allosteric site to potentiate the response to the endogenous agonist. In general, these compounds tend to be more selective for the intended receptor because they do not interact with the highly conserved neurotransmitter binding site. Another major breakthrough occurred when other laboratories discovered a novel class of M1 agonists that interact with an ectopic site on the receptor rather than the ACh binding site. Unlike traditional agonists, these compounds are highly specific for M1 relative to other mAChR subtypes and provide exciting new tools to definitively determine whether the physiological and behavioral effects of mAChR agonists thought to be important for antipsychotic activity are mediated by M1. In the proposed studies, we will take advantage of automated technologies and a high throughput screen for allosteric potentiators of M1 that we have developed to identify novel compounds that act as highly selective allosteric potentiators of this receptor. In addition, we will use these compounds along with the new selective ectopic site M1 agonists, a novel M4 allosteric potentiator and a panel of mice in which specific mAChR subtypes have been deleted to test the hypothesis that the antipsychotic-like profile of muscarinic agonists is mediated by M1 and to determine whether allosteric potentiators of M1 have electrophysiological and behavioral effects that are similar to those of M1 agonists
Keywords: (3-O-hexyloxy)-TZTP; 2-(Acetyloxy)-N, N, N-trimethylethanaminium; 3-(3-O-hexyl-1, 2, 5-thiadiazol-4-yl)-1, 2, 5, 6-tetrahydro-1-methylpyridine; 4-n-butyl-1-(4-(2-methylphenyl)-4-oxo-1-butyl)-piperidine hydrogen chloride; AC-42; AC42; Acetylcholine; Acetylcholine Agents; Adverse effects; Agonist; Allosteric Site; Ammon Horn; Antipsychotic Agents; Antipsychotic Drugs; Antipsychotics; Assay; Behavioral; Binding Sites; Bioassay; Biologic Assays; Biological Assay; Cells; Chemicals; Cholinergic Agents; Cholinergic Agonists, Muscarinic; Cholinergic Drugs; Cholinergics; Clinical; Clinical Research; Clinical Study; Cognitive; Combining Site; Cornu Ammonis; Degenerative Diseases, Nervous System; Degenerative Neurologic Disorders; Development; Drugs; Ethanaminium, 2-(acetyloxy)-N, N, N-trimethyl-; FOS gene; Fore-Brain; Forebrain; G Protein-Complex Receptor; G-Protein-Coupled Receptors; G0S7; High Throughput Assay; Hippocampus; Hippocampus (Brain); Industry; Investigators; Knockout Mice; Laboratories; Libraries; M1 receptor; Major Tranquilizers; Mammals, Mice; Measures; Mediating; Medication; Mice; Mice, Knock-out; Mice, Knockout; Modeling; Murine; Mus; Muscarinic Acetylcholine Receptor; Muscarinic Agonists; Muscarinic M1 Receptor; Nerve Transmitter Substances; Neurodegenerative Diseases; Neurodegenerative Disorders; Neuroleptic Agents; Neuroleptic Drugs; Neuroleptics; Neurologic Degenerative Conditions; Neurologic Diseases, Degenerative; Neurotransmitters; Nucleus Accumbens; Null Mouse; Patients; Pharmaceutic Preparations; Pharmaceutical Preparations; Physiologic; Physiological; Prefrontal Cortex; Process; Programs (PT); Programs [Publication Type]; Property; Property, LOINC Axis 2; Prosencephalon; Protooncogene FOS; Psychoses; Psychotic Disorders; Reactive Site; Receptor Activation; Receptor Protein; Receptor Signaling; Receptor, Muscarinic M1; Receptors, Muscarinic; Relative; Relative (related person); Research Personnel; Researchers; Role; Schizophrenia; Schizophrenic Disorders; Site; Specificity; Structure; Symptoms; Technology; Testing; Tranquilizing Agents, Major; Transmission; Treatment Side Effects; Wild Type Mouse; atypical antipsychotic; c fos; c-fos Gene; c-fos Proto-Oncogenes; cholinergic; clinical effect; cognitive function; dementia praecox; drug/agent; high throughput screening; hippocampal; immunoreactivity; improved; neurodegenerative illness; new approaches; novel; novel approaches; novel strategies; novel strategy; patch clamp; programs; receptor; response; schizophrenic; side effect; small molecule; small molecule libraries; social role; therapy adverse effect; tool; transmission process; treatment adverse effect; v-FOS FBJ Murine Osteosarcoma Viral Oncogene Homolog; xanomeline
Project start date: 2006-01-01
Project end date: 2010-12-31
Budget start date: 1-JAN-2010
Budget end date: 31-DEC-2010
5R01MH073676-05 (2010): $316729
5R01MH073676-02 (2007): $316213
Muscarinic Receptor Activators As Antipsychotic Agents
P Jeffrey Conn, Professor
Vanderbilt University Medical Center Nashville, Tn 372036869
Grant 1R01MH073676-01A1 from National Institute Of Mental Health IRG: ZRG1
Abstract: Recent clinical studies reveal that agents that activate muscarinic acetylcholine receptors (mAChRs) have robust efficacy in reducing psychotic symptoms in patients with schizophrenia as well as AD and other neurodegenerative disorders. Evidence suggests that the antipsychotic effects of cholinergic agents may be mediated by the M1 mAChR subtype. However, previous compounds developed to selectively activate M1 receptors lack true specificity for M1. This has resulted in problems with adverse effects due to M2 and M3 activation in patients and has made it impossible to definitively determine whether the behavioral and clinical effects of these compounds are mediated by M1 or other mAChR subtypes. Despite major efforts by multiple industry and academic laboratories, it has been impossible to develop clinically useful highly selective M1 agonists that act the orthosteric acetylcholine (ACh) binding site. This is likely due to the high degree of conservation of the ACh site between mAChR subtypes. In recent years we have been highly successful in establishing a new class of compounds that act as allosteric potentiators of G protein-coupled receptors that may provide key advantages to direct-acting agonists. Unlike agonists, these compounds do not directly activate the receptor but act at an allosteric site to potentiate the response to the endogenous agonist. In general, these compounds tend to be more selective for the intended receptor because they do not interact with the highly conserved neurotransmitter binding site. Another major breakthrough occurred when other laboratories discovered a novel class of M1 agonists that interact with an ectopic site on the receptor rather than the ACh binding site. Unlike traditional agonists, these compounds are highly specific for M1 relative to other mAChR subtypes and provide exciting new tools to definitively determine whether the physiological and behavioral effects of mAChR agonists thought to be important for antipsychotic activity are mediated by M1. In the proposed studies, we will take advantage of automated technologies and a high throughput screen for allosteric potentiators of M1 that we have developed to identify novel compounds that act as highly selective allosteric potentiators of this receptor. In addition, we will use these compounds along with the new selective ectopic site M1 agonists, a novel M4 allosteric potentiator and a panel of mice in which specific mAChR subtypes have been deleted to test the hypothesis that the antipsychotic-like profile of muscarinic agonists is mediated by M1 and to determine whether allosteric potentiators of M1 have electrophysiological and behavioral effects that are similar to those of M1 agonists.
Keywords: antipsychotic agent, drug discovery /isolation, drug screening /evaluation, muscarinic receptor, receptor expression, acetylcholine, allosteric site, binding site, genetically modified animal, hippocampus, nucleus accumbens, prefrontal lobe /cortex, protein structure function, psychopharmacology, receptor binding, small molecule, electrophysiology, high throughput technology, laboratory mouse, laboratory rat, voltage /patch clamp
Project start date: 2006-01-01
Project end date: 2010-12-31
1R01MH073676-01A1 (2006): $324063
REGULATION OF SIGNALING BY MGLUR5
P Jeffrey Conn, Professor
Pharmacologyemory University
1599 Clifton Road, 4th Floor
atlanta, Ga 30322
Grant 1R01MH062646-01 from National Institute Of Mental Health IRG: ZRG1
Abstract: DESCRIPTION(Adapted from applicant´s ) The hippocampus is a limbic cortical structure that plays an important role in learning and memory, and is a primary site of temporal lobe epilepsy and Alzheimer´s disease. Glutamate is the primary neurotransmitter at excitatory synapses in the hippocampus, where it acts on both ionotropic and metabotropic glutamate receptors (mGluRs). Particular attention has been focused on the NMDA subtype of glutamate receptor because of its unique role in certain forms of learning, memory, and pathological conditions including epileptic responses and excitotoxicity. Interestingly, recent studies reveal that activation of one mGluR subtype, mGluR5, can dramatically potentiate currents through NMDA receptor channels in hippocampal neurons. Furthermore, low concentrations of NMDA potentiate responses to mGluR5 activation. This positive feedback regulation between mGluR5 and NMDA receptors could play a critical role in signal amplification and may be important for NMDA receptor function. Consistent with this, several previous studies suggest that mGluR5 plays an important role in several receptor-dependent forms of synaptic plasticity and could contribute to pathological responses to NMDA receptor activation. Previous studies reveal that mGluR5 is desensitized by activation of protein kinase C (PKC) which directly phosphorylates the receptor. We recently found that mild activation of NMDA receptors-with low concentrations of NMDA-potentiates mGluR5-mediated responses by reversing this agonist-induced desensitization. Interestingly, stronger activation of NMDA receptors reduced mGluR5-mediated responses and increased mGluR5 phosphorylation. This is especially interesting in light of recent studies that suggest that low frequency stimulation of glutamatergic afferents to hippocampal area CA1 induces preferential activation of the protein phosphatase calcineuron whereas high frequency stimulation leads to activation of PKC and a net increase in protein phosphorylation. Based on this and a number of other previous studies, we postulated that the differential effects of different concentrations of NMDA on mGluR5 are mediated by net increases and decreases in mGluR5 phosphorylation. Furthermore, we postulate that low frequency stimulation of glutamatergic afferents induces preferential dephosphorylation of mGluR5 and potentiates mGluR5-mediated responses whereas high frequency stimulation induces a net increase in mGluR5 phosphorylation and inhibition of mGluR5-mediated responses. A combination of molecular, biochemical and electrophysiological techniques will be used to directly test these hypotheses
Keywords: NMDA receptor, biological signal transduction, glutamate receptor, neural transmission, phosphorylation, receptor expression calcium flux, hippocampus, long term potentiation, motor neuron, neural plasticity, phosphatase inhibitor, protein kinase C Xenopus oocyte, electrophysiology, gene targeting, laboratory mouse, tissue /cell culture, transgenic animal, voltage /patch clamp
Project start date: 2001-02-15
Project end date: 2006-01-31
1R01MH062646-01 (2001): $343313
CELLULAR MECHANISMS OF KINDLING-INDUCED EPILEPTOGENESIS
P Jeffrey Conn, Professor
Pharmacologyemory University
1599 Clifton Road, 4th Floor
atlanta, Ga 30322
Grant 5R29NS028405-05 from National Institute Of Neurological Disorders And Stroke IRG: NLS
Abstract: Daily low intensity tetanic of stimulation of limbic and forebrain structures with stimulus intensities that initially elicit little or no behavioral response, gradually leads to development of generalized clonic convulsions. This phenomenon, referred to as kindling, represents a permanent change in neuronal function that persists for the life of the animal. Kindling serves as an excellent model system for studying the cellular mechanisms involved in expression of long-lasting changes in neuronal excitability that underlie epilepsy, as well as such processes as learning and memory. Recent studies suggest that the pyriform cortex (PC) plays a key role in kindling-induced epileptogenesis and that kindling results in prolonged enhancement of responses of pyramidal cells within this structure to stimulation of excitatory affects. Evidence suggests that activation of excitatory amino acid (EAA) receptors is important for development of kindling but the precise role that EAA receptors play bringing about kindling-induced changes in neuronal excitability is unknown. Kindling induces a long-lasting increase in EAA-stimulated inositol phosphate formation in amygdala/PC slices and may induce changes in the sensitivity of other EAA receptors. In the proposed studies the effect of kindling on EAA-induced formation of the physiologically relevant phosphoinositide hydrolysis-derived second massagers, diacylglycerol (DAG) and inositol-1,4,5-triphosphate (Ins[1,4,5]P3), will be measured directly to test the hypothesis that kindling enhances EAA-induced formation of these second messengers. Current clamp and single electrode voltage clamp techniques will then be used to determine whether increased formation of DAG and Ins[1,4,5]P3 increases modulation of specific ionic conductances that are important for limiting repetitive firing in vertebrate neurons. The conductances that will be investigated are known to be inhibited by phosphoinositide hydrolysis-derived second messengers and if kindling enhances inhibition of these currents, this could enhance repetitive firing and lead to seizure activity. In addition, current clamp techniques will be used to test hypothesis that kindling also increases the sensitivity of other EAA receptors and thereby enhances excitatory synaptic transmission in the PC. Finally biochemical and biophysical techniques will be used to test the hypothesis that activation of the N-methyl-D-aspartate (NMDA) subtype of EAA receptor and active form of protein kinase C. This could contribute to induction of seizure activity by inducing tonic modulation of specific ionic conductances by this enzyme. Thus, if a constitutively active for of PKC is generated, current clamp and single electrode voltage clamp techniques may reveal changes in electrical properties of PC pyramidal cells that contribute to induction of seizure activity. It is likely that these studies will further our understanding of the cellular mechanisms involved in expression of lasting changes in neuronal excitability in general, and the pathophysiology of epilepsy in particular
Keywords: cellular pathology, epilepsy, excitatory aminoacid, kindling aspartate, brain metabolism, cerebellar cortex, diacylglycerol, electrophysiology, generalized seizure, glutamate receptor, guanine nucleotide binding protein, inositol phosphate, memory disorder, neural plasticity, neurotransmitter receptor, phosphatidylinositol, protein kinase C, pyramidal cell, second messenger electrolyte balance, electrostimulus, hydrolysis, laboratory rat, membrane channel, synaptic vesicle
Project start date: 1990-04-01
Project end date: 1995-03-31
5R29NS028405-05 (1994): $98927
Sponsored Links Excellgen http://Excellgen.com
VANDERBILT NCDDDG FOR DISCOVERY OF NOVEL TREATMENTS FOR SCHIZOPHRENIA
P Jeffrey Conn, Professor
Vanderbilt University, Medical Center, Nashville, Tn 37203-6869
Grant 1U01MH087965-01 from National Institute Of Mental Health
Abstract: Currently available antipsychotics for schizophrenia are not effective for the treatment of all major symptoms associated with the disease and are associated with a number of dose-limiting adverse effects. Thus, there is a critical need to develop novel therapeutic agents for treatment of schizophrenia that have broader efficacy and fewer adverse effects than currently available medications. We propose studies aimed at discovery and optimization of novel drug candidates for treatment of schizophrenia that are mechanistically unrelated to currently available antipsychotic agents and have the potential to provide efficacy in treatment of all major symptom clusters of this disease. The most advanced of these programs is focused on discovery of novel compounds that inhibit the glycine transporter 1, GlyT1. Glycine is a co-agonist with glutamate at the A/-methyl-D-aspartate (NMDA) subtype of glutamate receptors and provides an excellent approach to increasing NMDA receptor function while maintaining activity dependence of NMDA receptor activation. A number of clinical and animals studies suggest that GlyTI inhibitors have exciting potential for treatment of schizophrenia. To date, we have optimized novel scaffolds of GlyTI inhibitors with excellent pharmacokinetic and brain penetration profiles, robust efficacy in animal models, and lack significant toxicity. A second program is focused on discovery and optimization of highly selective allcsteric agonists of the M1 muscarinic acetylcholine receptor. We have established a novel approach to development of highly selective agonists of the M1 muscarinic acetylcholine receptor by targeting allosteric sites and have shown that these compounds have robust efficacy in animal models that predict efficacy in treatment of schizophrenia. Both the Ml and GlyTI programs are based on strong validation from animal models and exciting clinical data that provide support for pursuing these novel targets. Our overall objective is to optimize drug candidates that interact with each of these targets. Ultimately, we will work with industry partners to develop these drug candidates in clinical studies. We will begin with lead optimization of GlyTI inhibitors, followed by hit-tc-lead and lead optimization of Ml allosteric agonists with a goal of advancing molecules that interact with each of these to a stage where they are ready for preclinical and clinical development. Finally, we have a pipeline of additional targets for which we have chemically diverse verified hits and early drug leads that are poised for full lead optimization efforts. While not specifically included in this application, this provides a robust discovery pipeline that will be important for the future directions of this program. PUBLIC HEALTH REVELANCE The major goal of this program is to discover novel drug candidates that will ultimately advance into clinical testing for treatment of schizophrenia. If successful, novel drugs that come from this effort could lead to a fundamental breakthrough in the treatment of this disorder and could dramatically improve the standard of care for this devastating disorder
Keywords: 3, 4-Dihydroxyphenethylamine; 4-(2-Aminoethyl)-1, 2-benzenediol; Absorption; Adverse effects; Affect; Agonist; Allosteric Site; Aminoacetic Acid; Animal Model; Animal Models and Related Studies; Animals; Antipsychotic Agents; Antipsychotic Drugs; Antipsychotics; Brain; CHRM1; CHRM1 protein, human; Cell Communication and Signaling; Cell Signaling; Characteristics; Chemicals; Cholinergic Receptor, Muscarinic 1; Clinical; Clinical Data; Clinical Evaluation; Clinical Research; Clinical Study; Clinical Testing; D Aspartate; Data; Dependence; Development; Disease; Disease Clusterings; Disorder; Dopamine; Dose-Limiting; Drug Kinetics; Drugs; Encephalon; Encephalons; Excretory function; Future; GLYT1; Glutamate Receptor; Glutamates; Glycine; Goals; Hydroxytyramine; Impairment; Intermediary Metabolism; Intracellular Communication and Signaling; L-Glutamate; Lead; METBL; Major Tranquilizers; Medication; Mental disorders; Mental health disorders; Metabolic Processes; Metabolism; Muscarinic Acetylcholine Receptor; Muscarinic Acetylcholine Receptor M1; N Methyl D aspartic Acid; N methyl D aspartate; N-Methyl-D-Aspartate Receptors; N-Methyl-D-aspartate; N-Methylaspartate; NMDA; NMDA Receptor-Ionophore Complex; NMDA Receptors; Nervous System, Brain; Neuroleptic Agents; Neuroleptic Drugs; Neuroleptics; Pb element; Penetration; Pharmaceutic Preparations; Pharmaceutical Preparations; Pharmacokinetics; Population; Process of absorption; Programs (PT); Programs [Publication Type]; Property; Property, LOINC Axis 2; Psychiatric Disease; Psychiatric Disorder; Public Health; Receptor Activation; Receptor Protein; Receptors, Muscarinic; Receptors, N-Methylaspartate; Schizophrenia; Schizophrenic Disorders; Series; Signal Transduction; Signal Transduction Systems; Signaling; Staging; Symptoms; System; System, LOINC Axis 4; Therapeutic Agents; Toxic effect; Toxicities; Tranquilizing Agents, Major; Transmission; Treatment Side Effects; Unspecified Mental Disorder; Validation; Work; absorption; base; biological signal transduction; clinical test; dementia praecox; disease/disorder; drug candidate; drug/agent; effective therapy; excretion; glycine transporter 1; heavy metal Pb; heavy metal lead; human CHRM1 protein; improved; in vivo; industry partner; inhibitor; inhibitor/antagonist; mental illness; model organism; monoamine; muscarinic cholinergic receptor 1, human; new approaches; new therapeutics; next generation therapeutics; novel; novel approaches; novel strategies; novel strategy; novel therapeutics; pre-clinical; preclinical; programs; psychological disorder; public health medicine (field); receptor; receptor function; receptor, muscarinic cholinergic Hm1, human; research clinical testing; scaffold; scaffolding; schizophrenic; side effect; standard of care; therapy adverse effect; transmission process; treatment adverse effect
Project start date: 2010-02-19
Project end date: 2014-12-31
Budget start date: 19-FEB-2010
Budget end date: 31-DEC-2010
PFA/PA: PAR-08-238
1U01MH087965-01 (2010): $1891522
CELLULAR MECHANISMS OF KINDLING INDUCED EPILEPTOGENESIS
P Jeffrey Conn, Professor
Emory University 1599 Clifton Road, 4th Floor Atlanta, Ga 30322
Grant 5R01NS028405-08 from National Institute Of Neurological Disorders And Stroke IRG: NLS
Abstract: Approximately 1% of the population suffers from a chronic seizure disorder, and of these temporal lobe epilepsy is the most common epileptic syndrome. one of the most widely accepted animal models of human temporal lobe epilepsy is referred to as kindling, a process in which daily low-intensity stimulation of limbic or forebrain structures gradually leads to development of limbic convulsions. Evidence suggests that the mechanisms underlying kindling involve changes in transmission at excitatory glutamatergic synapses. However, the precise mechanisms involved in kindling-induced epileptogenesis are unknown. Fast excitatory synaptic transmission at glutamatergic synapses is mediated by activation of heteromeric glutamate receptor cation channels. Preliminary studies indicate that kindling results in a selective reduction in one of four known subunits of the AMPA subtype of glutamate receptor, termed GluR2. This effect occurs only in piriform cortex, a brain region that has been implicated as playing a major role in kindling. Interestingly, the GluR2 AMPA receptor subunit plays a unique role in reducing the calcium permeability of AMPA receptors. AMPA receptors that contain GluR2 are calcium impermeable whereas AMPA receptors that lack GluR2 are highly permeable to calcium. If the kindling-induced reduction in GluR2 leads to an increase in calcium permeability of AMPA receptors, this could play an important role in induction of calcium-dependent forms of synaptic plasticity that eventually lead to epileptogenesis. However, it is not known whether the kindling-induced change in GluR2 leads to a physiologically relevant change in AMPA receptor function. A series of experiments is proposed in which electrophysiological techniques will be used to test the hypothesis that the kindling-induced reduction in GluR2 leads to a functionally relevant change in AMPA receptor subunit composition and an increase in AMPA receptor calcium permeability. Another change that occurs in glutamatergic systems with kindling is a long lasting increase in extracellular glutamate concentrations. This may be mediated by a kindling-induced reduction in levels of glutamate transport proteins. However, this hypothesis has not been tested directly. Three glutamate transport proteins have now been cloned. Antibodies that specifically react with each of the cloned glutamate transporters will be used with quantitative western blotting to test the hypothesis that kindling reduces levels of glutamate transport proteins. A series of experiments will then be performed to test the hypothesis that this leads to a functionally relevant reduction in glutamate uptake. If we find that kindling induces physiologically relevant changes in levels of GluR2 and transport proteins, we ultimately hope to determine the overall impact of these changes on transmission through specific neuronal circuits that are known to play an important role in temporal lobe epilepsy.
Keywords: epilepsy, glutamate, glutamate receptor, membrane transport protein, receptor expression, calcium flux, kainate, kindling, lateral olfactory area, limbic system, neuroanatomy, neuropharmacology, neurotransmitter transport, protein isoform, pyramidal cell, high performance liquid chromatography, laboratory rat, microdialysis, patch clamp, western blotting
Project start date: 1990-04-01
Project end date: 1999-02-28
5R01NS028405-08 (1997): $219820
CONTROL OF NMDA RECEPTORS BY HIPPOCAMPUS MUSCARINIC REC
P Jeffrey Conn, Professor
Emory University 1599 Clifton Road, 4th Floor Atlanta, Ga 30322
Grant 1R01NS036755-01 from National Institute Of Neurological Disorders And Stroke IRG: NLS
Abstract: Applicant s ) The hippocampus plays an important role in memory formation and is a primary site of pathology in several neurological disorders including Alzheimer s disease (AD) and epilepsy. Cholinergic projections to the hippocampus provide a major neuromodulatory input to glutamatergic neurons and synapses in the hippocampus and are critical for memory and attention mechanisms. Cholinergic transmission in the hippocampus is mediated primarily by muscarinic acetylcholine receptors (mAChRs), which have been classified into m1-m5 subtypes. One of the most prominent effects of mAChR activation in the hippocampus is a marked potentiation of currents through the NMDA subtype of glutamate receptor. This is likely to enhance NMDA receptor-dependent LTP and could play an important role in cholinergic regulation of cognitive function. Development of a complete understanding of the mechanisms involved in cholinergic modulation of NMDA receptor currents could be useful for development of agents that are effective in ameliorating the loss of cognitive function in patients with AD and other memory disorders. Recent studies and preliminary data from this laboratory suggest that mAChR-induced activation of tyrosine kinases in hippocampal slices may be necessary for potentiation of NMDA receptor currents. A series of studies is proposed to rigorously test the hypothesis that mAChR activation results in tyrosine phosphorylation of NMDA subunits and that tyrosine phosphorylation of NMDA receptor subunits is necessary for mAChR-induced potentiation of NMDA-evoked currents. Specific inhibitors of tyrosine kinases and mutant mice lacking major non-receptor tyrosine kinases will be used in a series of electrophysiology studies to determine whether activation of tyrosine kinases is required for potentiation of NMDA receptor currents. Biochemical and molecular approaches will then be used to identify tyrosine phosphorylation sites on NMDA receptor subunits involved in tyrosine kinase-induced potentiation of NMDA-evoked currents and determine whether mAChR activation increases phosphorylation of these sites on NMDA receptor subunits in hippocampal slices. Finally, mAChR subtype-specific toxins and other subtype-specific agents will be used to determine which mAChR subtypes mediate mAChR-induced phosphorylation of NMDA receptor subunits. Immunocytochemistry with double labeling and confocal microscopy will then be used to verify that these mAChR subtypes are colocalized on hippocampal neurons with the NMDA receptor subunits that are phosphorylated by mAChR activation.
Keywords: NMDA receptor, enzyme activity, hippocampus, muscarinic receptor, protein tyrosine kinase, enzyme inhibitor, phosphoprotein, phosphorylation, confocal scanning microscopy, immunocytochemistry, laboratory mouse, laboratory rat, patch clamp
Project start date: 1997-09-30
Project end date: 2001-05-31
1R01NS036755-01 (1997): $216598
5R01NS036755-04 (2000): $215532
5R01NS036755-02 (1998): $203160
HIGHLY SELECTIVE MUSCARINIC AGENTS AS ANTIPARKINSONIAN THERAPY
P Jeffrey Conn
Emory University, 1599 Clifton Road, 4th Floor, Atlanta, Ga 30322
Abstract: Antagonists at muscarinic acetylcholine receptors (mAChRs) are commonly used in parkinsonian patients as an alternative to dopaminergic replacement therapies. The mAChR antagonists are very effective for treating symptoms, but their clinical utility is often limited by significant central and peripheral side effects. It is likely that the adverse effects of mAChR antagonists are due to the fact that available compounds are nonselective and have similar antagonist potencies at all of the five mAChR subtypes (termed Ml - M5). Development of an understanding of the individual mAChR subtypes involved in modulating basal ganglia function could provide a basis for development of mAChR antagonists that selectively block individual mAChR subtypes and may have antiparkinsonian efficacy with reduced adverse effect liability compared with the non-selective mAChR antagonists. We have made a major breakthrough in developing the first highly selective allosteric modulators of M1, M4, and M5 mAChR subtypes. In preliminary studies, we found that Ml, M4 and M5 mAChRs regulate neuronal excitability and inhibitory synaptic transmission in key nuclei of the basal ganglia. Specifically, the available data suggest to us that blockade of Ml and/or M4 mAChRs could have antiparkinsonian effects through reduction of pathologically increased and abnormally patterned neuronal activity in the subthalamic nucleus or the substantia nigra pars reticulata, while M5 activation may be beneficial, as M5 receptors appear to depolarize neurons in the substantia nigra pars compacta which may increase striatal dopamine levels. In the proposed studies, we plan to test these hypotheses by a thorough analysis of the electrophysiologic effects of our novel subtype-specific mAChR active compounds, and through in-vivo testing of these agents in acute and chronic rodent models of Parkinson´s disease. Parallel immunohistochemcal studies (Core B) will examine the synaptic and subcellular distribution of the mAChR subtypes in the subthalamic nucleus and substantia nigra. These experiments are highly significant, as they may identify new classes of antiparkinsonian agents that promise effective treatment of parkinsonian patients with fewer side effects than currently possible
Keywords: 3, 4-Dihydroxyphenethylamine; 4-(2-Aminoethyl)-1, 2-benzenediol; Acute; Address; Adverse effects; Agents, Muscarinic; Animal Model; Animal Models and Related Studies; Animals; Antiparkinson Agents; Antiparkinson Drugs; Antiparkinsonian Agents; Antiparkinsonians; Area; Basal Ganglia; Basal Nuclei; Behavioral; Cell Nucleus; Cell/Tissue, Immunohistochemistry; Cells; Chronic; Clinical; Corpus Striatum; Corpus striatum structure; DA Neuron; Data; Development; Disease; Disorder; Dopamine; Dopamine neuron; Drugs; Electrophysiology; Electrophysiology (science); Hydroxytyramine; IHC; Idiopathic Parkinson Disease; Immunohistochemistry; Immunohistochemistry Staining Method; Impairment; In Vitro; Individual; Injection of therapeutic agent; Injections; Knockout Mice; Lead; Lewy Body Parkinson Disease; Ligands; M1 receptor; Medication; Mice, Knock-out; Mice, Knockout; Motor; Muscarinic Acetylcholine Receptor; Muscarinic M1 Receptor; Muscarinics; N-Methyl-D-Aspartate Receptors; NMDA Receptor-Ionophore Complex; NMDA Receptors; Nerve Cells; Nerve Transmitter Substances; Nerve Unit; Neural Cell; Neural Transmission; Neurocyte; Neurons; Neurophysiology / Electrophysiology; Neurotransmitters; Nucleus; Nucleus Subthalamicus; Nucleus tegmentalis pedunculopontinus; Null Mouse; Output; Paralysis Agitans; Parkinson; Parkinson Disease; Parkinson`s; Parkinson`s disease; Parkinsonian; Parkinsonian Condition; Parkinsonian Diseases; Parkinsonian Disorders; Parkinsonian Syndrome; Parkinsonism; Parkinsons disease; Patients; Pb element; Pedunculopontine Tegmental Nucleus; Peripheral; Pharmaceutic Preparations; Pharmaceutical Preparations; Physiologic; Physiological; Primary Parkinsonism; Receptor Protein; Receptor, Muscarinic M1; Receptors, Muscarinic; Receptors, N-Methylaspartate; Regulation; Relative; Relative (related person); Replacement Therapy; Rodent Model; Role; Series; Staging; Striate Body; Striatum; Structure of subthalamic nucleus; Substantia Nigra; Substantia nigra structure; Subthalamic Nucleus; Symptoms; Synapses; Synaptic; Synaptic Transmission; System; System, LOINC Axis 4; Testing; Thalamic structure; Thalamus; Transmission; Treatment Efficacy; Treatment Side Effects; base; cholinergic; disease/disorder; dopaminergic neuron; drug/agent; effective therapy; experiment; experimental research; experimental study; heavy metal Pb; heavy metal lead; improved; in vivo; model organism; neuronal; neuronal excitability; neuronal patterning; novel; novel therapeutic intervention; pars compacta; patch clamp; receptor; research study; response; side effect; social role; striatal; thalamic; therapeutic efficacy; therapeutically effective; therapy adverse effect; traditional therapy; transmission process; treatment adverse effect
Relevance: The proposed studies evaluate the utility of subtype-selective muscarinic receptor antagonists to normalize basal ganglia activity in parkinsonian animals in vitro, and to have antiparkinsonian effects in vivo. If successful, these studies may identify a group of highly effective antiparkinsonian drugs with fewer side effects that currently available treatments
Budget start date: 30-SEP-2010
Budget end date: 31-AUG-2011
PFA/PA: RFA-NS-10-001
1P50NS071669-01_6626 (2010): $259653
FUNCTIONAL EFFECTS OF MGLUR POTENTIATORS IN THE CNS
P Jeffrey Conn, Professor
Vanderbilt University, Medical Center, Nashville, Tn 37203-6869
Grant 5R01MH074953-05 from National Institute Of Mental Health
Abstract: Animal and clinical studies suggest that agonists of group II metabotropic glutamate (mGlu) receptors (mGlu2 and mGlu3) could provide a novel approach for the treatment of anxiety disorders and schizophrenia. However, group II mGlu receptor agonists activate both mGlu2 and mGlu3, and the relative contributions of these two receptor subtypes to the actions of these drugs are not known. Thus, there is a critical need to determine whether activation of a specific group II mGlu receptor subtype (mGlu2 or mGlu3) could elicit the behavioral and electrophysiological effects of group II mGlu receptor agonists that are relevant to their potential therapeutic efficacy. Furthermore, development of tolerance and adverse effects of direct agonists could limit their clinical use. Thus, it will be important to develop novel approaches to increasing activity of these receptors that may have advantages relative to direct agonists. In recent months, a novel class of compounds has been discovered that act as selective allosteric potentiators of the mGlu2 receptor subtype. These compounds do not activate mGlu2 directly but act at an allosteric site to potentiate glutamate-induced activation of the receptor. These compounds represent the first clear departure from glutamate analogs as mGlu2 activators are the first compounds that are highly selective for mGlu2 relative to mGlu3 or other mGlu receptor subtypes. However, the functional effects of these compounds in systems relevant to the therapeutic efficacy of group II mGlu receptor agonists have not been determined. We propose a series of studies in which we will determine the effects of allosteric potentiators of mGlu2 on electrophysiological responses to group II mGlu receptor activation in cell populations that have been postulated to be important for the therapeutic effects of these compounds. In addition, we will systematically evaluate the behavioral effects of allosteric mGlu2 potentiators in animal models predictive of anxiolytic and antipsychotic activity. Finally, we will determine whether direct agonists and allosteric potentiators differ in their propensity to induce desensitization and behavioral tolerance after chronic administration. These studies will build on the exciting advances suggesting a potential therapeutic utility of group II mGlu receptor activators and could provide a novel approach to increasing activity of these receptors that for development of new therapeutic agents
Keywords: Address; Adverse effects; Agonist; Allosteric Site; Animal Model; Animal Models and Related Studies; Animals; Anti-Anxiety Agents; Anti-Anxiety Drugs; Antipsychotic Agents; Antipsychotic Drugs; Antipsychotics; Anxiety Disorders; Anxiolytic Agents; Anxiolytics; Behavioral; Benzodiazepine Compounds; Benzodiazepines; Brain; Brain region; Cells; Chronic; Clinical; Clinical Research; Clinical Study; Coupling; Development; Drug effect disorder; Encephalon; Encephalons; Generalized Anxiety Disorder; Glutamate Agonist; Glutamates; Investigators; Ion Channel; Ionic Channels; L-Glutamate; Major Tranquilizers; Mammals, Mice; Membrane Channels; Metabotropic Glutamate Receptors; Mice; Molecular; Murine; Mus; Nervous System Diseases; Nervous System, Brain; Neuroleptic Agents; Neuroleptic Drugs; Neuroleptics; Neurologic Disorders; Neurological Disorders; Panic Attack; Physiologic; Physiological; Population; Programs (PT); Programs [Publication Type]; Receptor Activation; Receptor Protein; Relative; Relative (related person); Research Personnel; Researchers; Safety; Schizophrenia; Schizophrenic Disorders; Series; Slice; System; System, LOINC Axis 4; Testing; Therapeutic; Therapeutic Agents; Therapeutic Effect; Tranquilizing Agents, Major; Tranquilizing Agents, Minor; Treatment Efficacy; Treatment Side Effects; analog; antianxiety agent; behavioral tolerance; clinical practice; dementia praecox; desensitization; drug action; in vivo; member; model organism; mouse model; nervous system disorder; neurological disease; new approaches; new therapeutics; next generation therapeutics; novel; novel approaches; novel strategies; novel strategy; novel therapeutics; programs; receptor; response; schizophrenic; side effect; small molecule; success; therapeutic efficacy; therapeutically effective; therapy adverse effect; treatment adverse effect; treatment strategy
Project start date: 2006-06-01
Project end date: 2011-05-31
Budget start date: 17-JUN-2010
Budget end date: 31-MAY-2011
5R01MH074953-05 (2010): $253382
5R01MH074953-04 (2009): $253382
3R01MH074953-04S1 (2009): $77500
5R01MH074953-02 (2007): $253314
Sponsored Links Excellgen http://Excellgen.com
1R01MH074953-01A1 (2006): $259958
Regulation Of Signaling By MGluR5
P Jeffrey Conn, Professor
Vanderbilt University Medical Center Nashville, Tn 372036869
Grant 2R01MH062646-07 from National Institute Of Mental Health IRG: MNPS
Abstract: A large number of anatomical, cellular, molecular, and behavioral studies have led to the hypothesis that selective activators of mGluRS may have exciting potential as novel antipsychotic and cognition-enhancing agents. While these studies represent a major advance in our understanding of mGluRS function, selective agonists of mGluRS have not been available to directly test this hypothesis in vivo. Unfortunately, it has been difficult to develop compounds that act as selective agonists of specific mGluR subtypes that have properties that are suitable for in vivo studies or ultimate development of therapeutic agents. Over the past year, we made a major breakthrough in developing a novel approach to activation of mGluRS using selective allosteric potentiators of this receptor. These compounds do not activate mGluR5 directly but dramatically potentiate the response of the receptor to glutamate. These allosteric potentiators offer high selectivity for mGluRS and provide an exciting new approach to development of novel selective activators of G protein-coupled receptor (GPCR) subtypes. One of these compounds, termed CDPPB, is systemically active, has a relatively long half life and readily crosses the blood brain barrier. This provides an unprecedented opportunity to determine the electrophysiological and behavioral effects of selective mGluRS potentiators. Furthermore, defining the precise domains of the receptors required for this action and the mechanisms involved in allosteric potentiation of mGluRs by CDPPB and its analogs will be important for further development of this approach to mGluR activation. We now propose a series of molecular, structure function, and pharmacological studies to rigorously test the hypothesis that potentiation of mGluRS responses by CDPPB and its analogs is mediated by binding to an allosteric binding site on mGluRS that also binds to allosteric antagonists of this receptor, such as MPEP. In addition, we will determine the electrophysiological effects of CDPPB on activation of mGluRS by exogenous agonists and stimulation of glutamatergic afferents in systems that may be important for potential antipsychotic and cognition-enhancing effects of this compound. Finally, we will determine the behavioral effects of CDPPB in animal models that have been used to assess potential antipsychotic and cognition-enhancing activity of novel agents. These studies will have a major impact on our understanding of mGluRS function and an exciting new approach to activation of this receptor with allosteric potentiators. In addition, these studies will have a major impact on thinking about the utility of allosteric potentiators for multiple other GPCRs where development of direct agonists has been problematic.
Keywords: NMDA receptor, allosteric site, aminoacid analog, biological signal transduction, drug discovery /isolation, glutamate receptor, neural transmission, antipsychotic agent, astrocyte, calcium indicator, cognition, electrophysiology, inhibitor /antagonist, neural information processing, neural plasticity, neuropharmacology, genetically modified animal, laboratory mouse, laboratory rat, single cell analysis, site directed mutagenesis, tissue /cell culture, voltage /patch clamp
Project start date: 2001-02-15
Project end date: 2011-01-31
2R01MH062646-07 (2006): $324240
P Jeffrey Conn
Vanderbilt University
Project start date: 2005-04-01
Project end date: 2015-11-30
CELLULAR MECHANISMS OF KINDLING INDUCED EPILEPTOGENESIS
P Jeffrey Conn, Professor
Emory University 1599 Clifton Road, 4th Floor Atlanta, Ga 30322
Grant 5R01NS028405-07 from National Institute Of Neurological Disorders And Stroke IRG: NLS
Project start date: 1990-04-01
Project end date: 1998-02-28
5R01NS028405-07 (1996): $211727
NEUROMODULATORY ROLES OF MUSCARINIC RECEPTOR SUBTYPES
P Jeffrey Conn, Professor
Emory University 1599 Clifton Road, 4th Floor Atlanta, Ga 30322
Grant 1R01NS034876-01 from National Institute Of Neurological Disorders And Stroke IRG: NLS
Project start date: 1996-02-01
Project end date: 2001-01-31
1R01NS034876-01 (1996): $160869
FUNCTIONS OF METABOTROPIC GLUTAMATE RECEPTOR SUBTYPES
P Jeffrey Conn, Professor
Emory University 1599 Clifton Road, 4th Floor Atlanta, Ga 30322
Grant 2R01NS031373-04 from National Institute Of Neurological Disorders And Stroke IRG: NLS
Project start date: 1993-08-01
Project end date: 2000-07-31
2R01NS031373-04 (1996): $229641