Emil Chris Muly, MD, PhD - US grants

DESCRIPTION (Verbatim from the Applicant's Abstract): The goal of the work proposed here is to directly relate cortical circuitry with the molecular components of neurotransmission: receptors and signal transduction proteins. We will study the relationship between the circuitry of primate prefrontal cortex and the D1 dopamine receptor and related molecules. This focus will allow us to relate our results to the circuitry of working memory, which is dysfunctional in schizophrenia. Working memory function depends on an optimal level of D1 receptor activation and is impaired by both over and under stimulation of D1 receptor. We hope that our results will lead to a better understanding of the mechanism of the D1 receptor's complex modulation of working memory, and ultimately to a better understanding of neuroleptic action. This work is comprised of four aims. 1) Identify the source of afferents that terminate onto D1-containing spines. This will suggest aspects of cortical circuitry that are critical for working memory function. We hypothesize that instrinsic axons target D1-containing spines, but not axons from distant sources. 2) Identify the source of afferents that terminate onto the spines that contain protein phosphatase 1 (PP1) isoforms. Pilot studies demonstrate that cortical spines can be subdivided based on their content of the isoforms PP1alpha and PP1gamma1. The results of this work will extend our understanding of the mechanisms by which cortical circuitry may be specialised. We hypothesize that afferents which do not terminate onto D1-containing spines still have access to the signal transduction pathway used by the D1 receptor. 3) Examine the subcellular distribution and relationship between D1, PP1alpha and PP1gamma1. The D1 receptor is found in spines that contain both PP1alpha and PP1gamma1. We hypothesize that the subcellular distribution of these isoforms differs within a single spine. If confirmed, this could suggest differential localization as the significance for multiple isoforms of a single protein within a spine. 4) Compare the distribution of group I metabotropic glutamate receptors (mGluRs) with that of the D1 receptor. Group I mGluRs potentiate D1 mediated effects in other brain areas. We hypothesize that one of these mGluRs will be found in the same spines as D1 receptors. This will add to our understanding of the interactions between G protein-coupled receptors. To accomplish these aims we will inject neuroanatomical tract tracers into the brains of young adult macaque monkeys to label parietal, thalamic and callosal afferents to prefrontal cortex, and within prefrontal cortex to label local horizontal and local intracolumnar axons. Double-labeling techniques appropriate for electron microscopy will be used to stain the labeled axons and either D1, PP1alpha or PP1gamma1. We will use serial section electron microscopy to determine if the postsynaptic targets of labeled axons contain these proteins. Post-embedding immunogold labeling will be used to examine the distribution of these proteins within a spine. Double-label experiments will directly compare their distribution and look for co-localization. Finally we will use single and pre-embedding double label methods to examine the subcellular localization of group I mGluRs and compare their distribution to that of the D1 receptor. The possibility of co-localization of the D1 receptor and the mGluR within a single spine will be examined.

prefrontal lobe /cortex; neurotransmitter transport; dopamine; intermolecular interaction; glutamates; Primates; animal colony;

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We study how dopamine acting at D1 family dopamine receptors (D1R;D1 and D5) affects the circuitry of brain regions relevant to schizophrenia, PTSD and substance abuse. These regions include prefrontal cortex (PFC), amygdala and nucleus accumbens (NAc). We completed our examination of D1R in (PFC) and published the results. We have further examined the distribution of D1R in prefrontal interneuron subtypes. We have found distinct patterns of localization of receptors in subpopulations of interneurons and proposed a detailed model for how dopamine stimulation of D1 family receptors controls pyramidal cell. A manuscript of this work is in press. We completed our study of D1R in monkey and rat amygdala, a brain region implicated in fear and anxiety disorders, as well as drug addiction. We found differences in the distribution between D1 and D5 and between PFC and amygdala. We found similar patterns of distribution between rat and monkey amygdala and similar cellular responses in monkey compared to previous reports in rat. These results are being prepared for submission. In addition, we examined the interneuron subtypes of the primate amygdala and found that PV interneurons in monkey are similar to those seen in rat. This work is in press. Our studies of D1R in NAc are nearly complete, and we are characterizing the distribution of components of the D1R signal transduction pathway: DARPP-32 and inhibitor-1. We have completed our analysis in PFC and are preparing a manuscript for submission. We are working to complete our analysis in the amygdala and NAc. Our study of the protein Lfc has pioneered a new localization assay and has been published. Finally, we published a study of mGluR2/3 in different parts of the amygdala and confirmed that our analyses reveal functionally significant differences.

1-Butanone, 4-(4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl)-1-(4-fluorophenyl)-; 4H-Pyrido(1,2-a)pyrimidin-4-one, 3-(2-(4-(6-fluoro-1,2-benzisoxazol-3-yl)-1-piperidinyl)ethyl)-6 ,7,8,9-tetrahydro-2-methyl-; Adverse effects; Age; Antipsychotic Agents; Antipsychotic Drugs; Antipsychotics; Benzamide, 3,5-dichloro-N-((1-ethyl-2-pyrrolidinyl)-methyl)-2-hydroxy-6-methoxy-; Binding; Binding (Molecular Function); Blood Serum; Blood drug level result; Brain; CRISP; Clinical Treatment; Compliance behavior; Computer Retrieval of Information on Scientific Projects Database; D2 receptor; DRD2; DRD2 Receptor; Dopamine D2 Receptor; Dopamine Receptor; Drugs; Encephalon; Encephalons; Family; Funding; Generations; Grant; Haldol; Haloperidol; Institution; Investigators; Major Tranquilizers; Marketing; Measurement; Medical Imaging, Positron Emission Tomography; Medication; Modeling; Molecular Interaction; NIH; National Institutes of Health; National Institutes of Health (U.S.); Nervous System, Brain; Neuroleptic Agents; Neuroleptic Drugs; Neuroleptics; PET; PET Scan; PET imaging; PETSCAN; PETT; Patient Compliance; Patient Cooperation; Patients; Pharmaceutic Preparations; Pharmaceutical Preparations; Positron Emission Tomography Scan; Positron-Emission Tomography; Proton Magnetic Resonance Spectroscopic Imaging; Raclopride; Rad.-PET; Receptor Protein; Research; Research Personnel; Research Resources; Researchers; Resources; Risperidone; Schizophrenia; Schizophrenic Disorders; Serum; Source; Tranquilizing Agents, Major; Treatment Compliance; Treatment Side Effects; United States; United States National Institutes of Health; atypical antipsychotic; blood level of drug; cohort; compliance cooperation; dementia praecox; drug/agent; non-human primate; nonhuman primate; patient adherence; receptor; resperidone; schizophrenic; side effect; therapy adverse effect; therapy compliance; therapy cooperation; treatment adverse effect; trial regimen; trial treatment