SYNAPTIC MECHANISMS OF BENZODIAZEPINE TOLERANCE

苯二氮卓耐受的突触机制

• 批准号: 3069562
• 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 1998-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3069562
• 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 研究科学家发展寻求支持 旨在系统调查的研究奖（二级） 苯二氮卓类（BZ）耐受性的突触机制。 这 该申请基于正在进行的、NIDA 资助的细胞外 海马电生理学和放射自显影结合研究 慢性氟西泮（FZP）治疗大鼠。 为了扩大这些调查范围， 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。 提议的研究是 初步研究的逻辑延伸总结和重要 未来的研究方向。 为了实现这些目标，使用 候选人所在机构和其他机构内的资源和顾问 概述了研究机构。 GABA/BZ/C1 通道复合物上各个结合位点的调节 与 BZ 耐受性有关。 据推测，药物诱导 长期 BZ 治疗导致 BZ 和 GABA 激动剂敏感性发生变化 GABA 复合体修饰的功能。 时间关系 与慢性 BZ 治疗相关的功能变化和 GABA 复合物的调节将在海马体（大脑的一个区域）中进行评估 网站特别适合测试这一点和相关的假设，在几个 停止 1 或 4 周氟西泮 (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 使用 GABA 能在体外海马体中进行电生理学研究 CA1 区域的循环和前馈抑制电路 基材。 细胞外分析将包括配对脉冲的研究 BZ 和 GABA 激动剂的抑制和浓度效应研究。 处死 48 小时大鼠海马切片的细胞外研究 FZP 治疗 1 周后表明配对脉冲抑制减少， 对 GABAA 激动剂不敏感，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 细胞外发现将在 CA1 中进行细胞内研究 锥体细胞。 对 GABA 激动剂的敏感性发生变化 使用离子电渗技术进行细胞内研究。 联系 修饰 GABA/BZ/C1 上的结合位点（GABA、BZ 和 C1 通道） 将研究通道复合体和站点间相互作用（耦合） 使用放射自显影方法。 mRNA 表达的调节 GABAA 受体亚基（α、β 和 γ）将用于研究 原位杂交方法。 GABA 复合体调控和基因表达 将在 5 个组织学鉴定的薄片中进行系统研究 与慢性 FZP 的功能后果存在时间相关性 BZ 和 GABA 激动剂治疗对 CA1 锥体细胞诱发的影响 电生理学测量的反应。