Mechanisms of Ligand-Induced GABA Receptor Plasticity

配体诱导 GABA 受体可塑性的机制

• 批准号: 6946683
• 负责人: RICHARD W OLSEN
• 金额: $ 22.6万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6946683
• 关键词: GABA receptor; benzodiazepines; biotin; cerebellum; drug tolerance; drug withdrawal; ethanol; gamma aminobutyrate; hippocampus; laboratory mouse; laboratory rat; neural plasticity; neurophysiology; protein localization; protein structure function; receptor binding; steroids; tissue /cell culture

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.

该成分的目标是分析中枢神经系统（CNS）中慢性GABA能诱导的可塑性的分子机制。各种可塑性诱导的处理会导致GABAA受体（GABAR）亚基Alpha4及其相关伙伴Gamma2或8的水平发生变化，并伴随着对 内源性神经素。在该计划中，我们确定含有α4​​Beta3delta亚基的Gabar是局部局部局部化的，参与了强直抑制作用，并且是神经类固醇和麻醉药对CNS兴奋性调节性的主要目标，包括乙醇，同时对苯并二氮杂素不敏感。特别是我们通过几种证据表明，加巴尔的α6Beta3delta亚型很可能是小脑乙醇的作用靶标。这一重要发现需要证明并形成目标。我们建议α4/6Beta3delta gabar既易于可塑性，又可以通过神经类固醇调节的强调抑制来调节兴奋性。在此项目目标II中，我们将在慢性类固醇（含外抗亚基亚基的靶标）和慢性BZ（突触GAMMA2亚基靶标）之后进行比较和对比变化。在药物治疗的小鼠中，我们将在生物化学上测量海马和小脑中Gabar亚基的水平，并使用抗体对亚基的伴侣，以及对GABAR水平的结合测定和指示亚基开关的变构调节。在药物处理的原发性海马神经元中，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合作伙伴。慢性GABA能药物后的塑料变化不仅与对临床有用剂（如苯二氮卓类药物（BZ）（BZ）以及戒断和依赖性的耐受性的发展有关，而且还与GABA系统控制兴奋性。反过来，这对于正常的中枢神经系统信息处理以及响应于通常或不寻常的经历（可塑性）（包括癫痫发生现象）而发生的变化至关重要。