SYNAPTIC MECHANISMS OF BENZODIAZEPINE TOLERANCE

苯二氮卓耐受的突触机制

• 批准号: 2116063
• 负责人: ELIZABETH I TIETZ
• 金额: $ 6.51万
• 依托单位: UNIVERSITY OF TOLEDO HEALTH SCI CAMPUS
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-01 至 1998-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2116063
• 关键词: GABA receptor; autoradiography; benzodiazepine receptor; benzodiazepines; chemical binding; chloride channels; drug interactions; drug tolerance; evoked potentials; flurazepam; gamma aminobutyrate; gel electrophoresis; gene expression; hippocampus; in situ hybridization; laboratory rat; membrane channels; messenger RNA; microelectrodes; nontherapeutic iontophoresis; northern blottings; pyramidal cells; radiotracer; stimulant /agonist; synapses

Support is being requested through an ADAMHA Research Scientist Development Award (Level II) for studies designed to systematically investigate the synaptic mechanisms underlying benzodiazepine (BZ) tolerance. The application is based on ongoing, NIDA funded, extracellular electrophysiological and autoradiographic binding studies in hippocampus of chronic flurazepam (FZP) treated rats. To broaden these investigations, intracellular and in situ hybridization studies are proposed as a part of the candidate's research career development plan. The studies proposed are a logical extension of the preliminary studies summarized and important direction for future research. To achieve these goals, the use of resources and consultants within the candidate's institution and other research institutions is outlined. Regulation of the various binding sites on the GABA/BZ/C1 channel complex has been implicated in BZ tolerance. It is hypothesized that drug-induced changes in BZ and GABA agonist sensitivity with chronic BZ treatment are a function of modifications at the GABA complex. The temporal relation between the functional changes associated with chronic BZ treatment and the regulation of GABA complex will be evaluated in the hippocampus, a brain site uniquely suited to test this and associated hypotheses, at several time-points after discontinuing a 1 or 4 week flurazepam (FZP) treatment. Functional changes in BZ and GABA agonist sensitivity will be measured electrophysiologically in in vitro hippocampus using the GABA-ergic recurrent and feed forward inhibitory circuits in CA1 region as a substrate. Extracellular analyses will include studies of paired-pulse inhibition and concentration-effect studies of BZ and GABA agonists. Extracellular studies in hippocampal slices from rats sacrificed 48 hr after 1 week FZP treatment indicate reduced paired-pulse inhibition, subsensitivity to GABAA agonists and tolerance to diazepam. The nature of the changes in local synaptic potentials which may be related to these extracellular findings will be investigated intracellularly in CA1 pyramidal cells. Alterations in the sensitivity to GABA agonists will be studied intracellularly using iontophoretic techniques. Associated modification of binding sites (GABA, BZ and C1 channel) on the GABA/BZ/C1 channel complex and site-site interactions (coupling) will be investigated using autoradiographic methods. Regulation of the expression of mRNAs for GABAA receptor subunits (alpha, beta and gamma) will be studied using in situ hybridization methods. GABA complex regulation and gene expression will be systematically studied in 5 histologically identified laminae and temporally correlated with the functional consequences of chronic FZP treatment on BZ and GABA agonists effects on CA1 pyramidal cell evoked responses measured electrophysiologically.

正在通过ADAMHA研究科学家发展项目请求支持。 奖（二级），奖励旨在系统调查 苯二氮卓类（BZ）耐受的突触机制。 的 应用程序是基于正在进行的，NIDA资助，细胞外 海马的电生理和放射自显影结合研究 慢性氟安定（FZP）处理的大鼠。 为了扩大调查范围， 细胞内和原位杂交研究被提议作为 候选人的研究职业发展计划。 拟议的研究包括 初步研究的逻辑延伸总结和重要 未来研究的方向。 为了实现这些目标， 候选人所在机构和其他机构的资源和顾问 研究机构概述。 GABA/BZ/C1通道复合物上各种结合位点的调节 与BZ耐受性有关 据推测，药物诱导的 BZ和GABA激动剂敏感性的变化与慢性BZ治疗是一个共同的结果。 GABA复合物修饰的功能。 的时间关系 与慢性BZ治疗相关的功能变化与 GABA复合物的调节将在海马体中进行评估，海马体是一种大脑 网站唯一适合测试这一点和相关的假设，在几个 在停止1或4周的泮（FZP）治疗后的时间点。 将测量BZ和GABA激动剂敏感性的功能变化 电生理学在体外海马使用GABA能 CA1区的递归和前馈抑制回路作为一种 衬底 细胞外分析将包括成对脉冲的研究 BZ和GABA激动剂的抑制和浓度效应研究。 48小时处死大鼠海马切片中的细胞外研究 FZP治疗1周后显示成对脉冲抑制减少， 对GABAA激动剂不敏感和对地西泮耐受。 的性质 局部突触电位的变化可能与这些有关， 将在CA 1细胞内研究细胞外发现 锥体细胞 对GABA激动剂敏感性的改变将是 使用离子电渗技术在细胞内进行研究。 关联 GABA/BZ/C1上结合位点（GABA、BZ和C1通道）的修饰 通道复合物和网站网站的相互作用（耦合）将进行研究 使用放射自显影方法。 基因表达的调控 GABAA受体亚单位（α、β和γ）将使用 原位杂交方法。 GABA复合物调控与基因表达 将在5个组织学鉴定的椎板中进行系统研究， 与慢性FZP的功能后果在时间上相关 BZ和GABA激动剂处理对CA1锥体细胞诱发的效应 电生理学测量的反应。