Mechanisms of Ligand-Induced GABA Receptor Plasticity

配体诱导 GABA 受体可塑性的机制

基本信息

批准号：
7586713
负责人：
RICHARD W OLSEN
金额：
$ 23.24万
依托单位：
UNIVERSITY OF CALIFORNIA LOS ANGELES
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/7586713
关键词：
Allopregnanolone Anesthetics Animals Antibodies Benzodiazepines Binding Biochemical Biological Assay Biotinylation Cell surface Cells Cerebellum Chronic Class Computer information processing Confocal Microscopy Control Animal Dendrites Dependence Development Epilepsy Ethanol Exhibits GABA Receptor Goals Hippocampal Formation Hippocampus (Brain)Interneurons Label Ligands Localized Location Measures Mediating Modeling Molecular Mus Neuraxis Neurons Pharmaceutical Preparations Pharmacological Treatment Pharmacology Physiological Pilocarpine Plastics Positioning Attribute Predisposition Property Prosencephalon Recurrence Research Personnel Seizures Site Steroids Structure of molecular layer of cerebellar cortex Subgroup Synapses System Temporal Lobe Epilepsy Testing Withdrawal Work analog base density dentate gyrus experience gamma-Aminobutyric Acid ganaxolone granule cell inhibitory neuron interest mouse model nervous system disorder neurochemistry programs receptor response

项目摘要

The objectives of this component are to analyze the molecular mechanisms of chronic GABAergic ligand-induced plasticity in the central nervous system (CNS). Various plasticity-inducing treatments produce changes in levels of the GABAA receptor (GABAR) subunit alpha4 and its associated partners, gamma2 or 8, accompanied by altered sensitivity to endogenous neurosteroids. In this program, we have determined that alpha4beta3delta subunit-containing GABAR are extrasynaptically localized, involved in tonic inhibition, and the major target of modulation of CNS excitability by neurosteroids and anesthetics including ethanol, while being insensitive to benzodiazepines. In particular we showed by several lines of evidence that the alpha6beta3delta subtype of GABAR is very likely the target of action of ethanol in the cerebellum. This important discovery needs substantiation and forms the rationale for Aim I. We suggest that the alpha4/6beta3delta GABAR are both susceptible to plasticity and positioned to regulate excitability via neurosteroid-modulated tonic inhibition. In this project Aim II we will compare and contrast changes in GABAR following chronic steroid (extrasynaptic delta subunit-containing target) and chronic BZ (synaptic gamma2 subunit-containing target). In drug-treated mice, we will measure biochemically the levels of GABAR subunits in hippocampus and cerebellum and partnering of subunits using antibodies, as well as binding assays for GABAR levels and allosteric modulation indicative of subunit switches. In drug-treated primary cultured hippocampal neurons, we will measure the content of cell surface GABAR subunits and subunit partners using biotinylation. Plastic changes following chronic GABAergic drugs are relevant not only to the development of tolerance to clinically useful agents like benzodiazepines (BZ) as well as withdrawal and dependence, but also to the control of excitability by the GABA system. This in turn is critically important to normal CNS information processing and changes that occur in response to usual or unusual experiences (plasticity), including epileptogenic phenomena.

该组件的目的是分析中枢神经系统 (CNS) 中慢性 GABA 配体诱导的可塑性的分子机制。各种可塑性诱导治疗会导致 GABAA 受体 (GABAR) 亚基 α4 及其相关伴侣 γ2 或 8 水平发生变化，并伴随着对内源性神经类固醇。在这个项目中，我们确定含有α4β3δ亚基的GABAR位于突触外，参与强直性抑制，是神经类固醇和麻醉剂（包括乙醇）调节中枢神经系统兴奋性的主要目标，同时对苯二氮卓类药物不敏感。特别是，我们通过多项证据表明，GABAR 的 alpha6beta3delta 亚型很可能是乙醇在小脑中的作用目标。这一重要的发现需要证实，并构成目标 I 的基本原理。我们认为 alpha4/6beta3delta GABAR 既易受可塑性影响，又可通过神经类固醇调节的强直抑制来调节兴奋性。在这个项目 Aim II 中，我们将比较和对比慢性类固醇（含有突触外 δ 亚基的靶标）和慢性 BZ（含有突触 γ2 亚基的靶标）后 GABAR 的变化。在药物治疗的小鼠中，我们将通过生化方法测量海马和小脑中 GABAR 亚基的水平以及使用抗体进行的亚基配对，以及 GABAR 水平的结合测定和指示亚基转换的变构调节。在药物处理的原代培养的海马神经元中，我们将测量细胞表面GABAR的含量使用生物素化的亚基和亚基伙伴。慢性 GABA 能药物引起的塑性变化不仅与临床上有用的药物如苯二氮卓类 (BZ) 的耐受性以及戒断和依赖性的发展有关，而且还与 GABA 系统兴奋性的控制有关。这反过来对于正常的中枢神经系统信息处理和响应通常或不寻常的经历（可塑性）而发生的变化至关重要，包括致癫痫现象。