SYNAPTIC MECHANISMS OF BENZODIAZEPINE TOLERANCE

正在通过ADAMHA研究科学家开发请求提供支持 奖项(II级)，旨在系统地研究 苯二氮(BZ)耐受的突触机制。这个 应用基于持续的、由NIDA资助的细胞外 大鼠海马区电生理和放射自显影结合研究 慢性氟安定(FZP)治疗大鼠。为了扩大调查范围， 细胞内和原位杂交研究被建议作为 候选人的研究职业发展计划。建议进行的研究包括 总结和重要的初步研究的逻辑延伸 未来研究的方向。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通道复合体上不同结合部位的调节 与苯扎酮的耐受性有关。据推测，毒品引起的 慢性BZ治疗对BZ和GABA激动剂敏感性的影响 GABA复合体的修饰功能。时间关系 与慢性BZ治疗相关的功能变化与 GABA复合体的调节将在大脑的海马体中进行评估 唯一适合于测试这一假设和相关假设的站点， 停用氟安定(FZP)1周或4周后的时间点。 将测量BZ和GABA激动剂敏感性的功能变化 用GABA能神经元对体外培养的海马区进行电生理学研究 CA1区的递归和前馈抑制回路 底物。细胞外分析将包括成对脉冲的研究 BZ和GABA激动剂的抑制作用及量效关系研究。 48小时大鼠海马脑片的细胞外研究 治疗1周后，FZP显示双脉冲抑制减少， 对GABAA激动剂的亚敏感性和对安定的耐受性。的性质 局部突触电位的变化可能与这些变化有关 CA1的细胞外表现将在细胞内进行研究 锥体细胞。对GABA激动剂敏感性的改变将是 使用离子导入技术在细胞内进行研究。关联的 GABA/BZ/C1上结合位点(GABA、BZ和C1通道)的修饰 将调查渠道复合体和站点-站点相互作用(耦合) 使用放射自显影方法。核糖核酸的表达调控 GABAA受体亚单位(阿尔法、贝塔和伽马)将在 原位杂交法。GABA复合体调控与基因表达 将在5个组织学鉴定的椎板和 与慢性FZP的功能后果的时间相关性 BZ和GABA激动剂治疗对CA1区锥体细胞诱发的影响 电生理学测量的反应。

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.