2010 — 2014 |
Xiao, Yingxian |
U19Activity Code Description: To support a research program of multiple projects directed toward a specific major objective, basic theme or program goal, requiring a broadly based, multidisciplinary and often long-term approach. A cooperative agreement research program generally involves the organized efforts of large groups, members of which are conducting research projects designed to elucidate the various aspects of a specific objective. Substantial Federal programmatic staff involvement is intended to assist investigators during performance of the research activities, as defined in the terms and conditions of award. The investigators have primary authorities and responsibilities to define research objectives and approaches, and to plan, conduct, analyze, and publish results, interpretations and conclusions of their studies. Each research project is usually under the leadership of an established investigator in an area representing his/her special interest and competencies. Each project supported through this mechanism should contribute to or be directly related to the common theme of the total research effort. The award can provide support for certain basic shared resources, including clinical components, which facilitate the total research effort. These scientifically meritorious projects should demonstrate an essential element of unity and interdependence. |
Selective Alpha4beta2 Nachr Desensitizers: in Vitro Pharmacological Properties
Neuronal nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that are implicated in a wide range of physiological functions, pathological processes and pharmacological effects. These receptors are the initial targets of nicotine and play an essential role in the development of nicotine addiction. In addition, these receptors may also be involved in developments of other addictions and in certain CNS disorders, including schizophrenia. Efforts to develop drugs targeting nAChRs have focused mainly on the ability of ligands to activate nAChRs. We hypothesize that many of the in vivo effects of nicotine in the CNS are mediated mainly by the desensitization of neuronal nAChRs, predominantly the 04(32 nAChRs. Based on our studies of in vitro pharmacological properties of sazetidine-A, a novel ligand that selectively desensitizes a4p2 nAChRs, we further hypothesized that (1) a nicotinic ligand that selectively desensitizes a4(32 nAChRs in vitro will produce some of the important in vivo effects of nicotine; and (2) such selective desensitizers of a4p2 nAChRs are potential therapeutic agents to aid smoking cessation. Based on these hypotheses, we propose to develop novel nicotinic therapeutics based desensitization of nAChR, rather than on activation of them. In the Project 1, our objective is to use in vitro pharmacological methods to profile novel ligands. We propose four Specific Aims to accomplish the objective: Aim 1, study equilibrium binding properties of all new ligands; Aim 2, study functional properties of new ligands using 86Rb+ efflux assays; Aim 3, study functional properties of new ligands using whole-cell patch clamp techniques; and Aim 4, characterize the pharmacological mechanisms related to desensitization induced by the novel ligands. The Aims of the Project 1 are closely related to proposed research in Project 2 (studies in animal behavioral models) and Project 3 (medicinal chemistry and animal tests for acute toxicity). We hope the collaborated efforts of the three projects will lead to drug candidates for Investigative New Drug applications, which may be used for treating nicotine addiction.
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2011 |
Xiao, Yingxian |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
High Throughput Screening For Nachrs: Cell Lines and Assay Development
DESCRIPTION (provided by applicant): The goal of this research project, which is highly responsive to NIH/NIDA RFA-DA-11-007, is to develop a high throughput screening (HTS) assay for screening and identifying selective ligands for neuronal nicotinic acetylcholine receptors (nAChRs) containing a3, a5, a6 and/or b4 subunits. nAChRs are ligand-gated ion channels that are implicated in a wide range of physiological functions, pathological processes and pharmacological effects. They have been shown to mediate the addictive effects of nicotine, which are the main reason why more than a billion people worldwide smoke cigarettes or use other tobacco products. Neuronal nAChRs are composed of a and b subunits that form pentameric cation channels. Nine a subunits (a2 - a10) and three b subunits (b2 - b4) have been identified in vertebrate neuronal tissues. Although the a7 subunit forms functional homomeric receptors, most nAChRs in mammalian brain are heteromeric receptors that contain two or more subunits. For many years, a4b2 nAChR subtypes (composed of a4, b2 and perhaps other subunits) have been the primary focus for studying nicotine addiction and developing smoking cessation therapeutics, and much evidence supports their involvement;but since 2007 genome-wide association studies have revealed significant associations of markers in the human a5-a3-b4 gene cluster on chromosome 15q24-25.1 with smoking and smoking related diseases. Among these markers, the most compelling variant is rs16969968, which changes an amino acid from aspartate to asparagine at position 398 (D398N) in the a5 subunit. This and more recent discoveries suggest that in addition to a4 and b2 subunits, a3, a5, a6 and b4 subunits play important roles in smoking and smoking related diseases. In light of this new information, it is considered important to develop new ligands selective for receptors containing a3, a5, a6 and/or b4 subunits. Hence, the crucial need for a HTS assay that can reliably identify selective ligands in existing or new libraries of compounds. We propose two Specific Aims to accomplish this goal: Aim 1: To establish highly functional stably transfected cell lines that express human nAChRs containing a3, a5, a6 and/or b4 subunits. Aim 2: To develop a functional HTS assay using IonFlux automated, high throughput patch clamp system. PUBLIC HEALTH RELEVANCE: Cigarette smoking is the leading cause of preventable disease and premature death in the United States. Selective ligands of nicotinic receptors can be used in studying nicotine addiction and for developing new smoking cessation therapeutics. The goal of this project is to develop high throughput screening assay that will accelerate the development of selective ligands.
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