MODULATORY SITES ON GABA A RECEPTORS

GABA-A受体受许多静脉全麻药(IV)的调节 气体)，以临床相关剂量。低浓度的静脉气体，如 麻醉剂类固醇，巴比妥酸盐和异丙酚，增强GABA 神经元的反应。较高的浓度，存在于血液中 静脉麻醉，直接激活GABA-A受体，开放Cl-通道， 从而降低神经元的兴奋性。这代表了一种机制，通过它 一些静脉气体可以达到麻醉效果。 GABA-A受体是由五个亚基组成的异质性受体。每个人 亚基可能是迄今克隆的15个品种之一。使用补丁- 记录单细胞GABA反应的钳制技术 具有不同亚基组合的受体已被发现具有 独特的药理特性。初步数据表明，GABA-A 神经性GT1-7细胞表达的受体组合不是 由高浓度的静脉注射气体直接激活。研究亚单位 静脉注射GAS、GABA-A调节和激活GABA-A受体的特异性 受体亚单位cDNA将被导入缺失的细胞系 内源性受体。这些细胞将首先被导入同源异构体。 感受器。这些将使用膜片钳技术进行测试，以 确定同构体受体是否具有功能(特定目标L)。 在确定了受体对GABA作出反应所需的亚基之后， 静脉注射GAS增强GABA反应所需的亚基如下 调查(具体目标2)。如果需要额外的亚单位 功能性受体，或静脉注射气体对GABA-A受体的调节，这些 将被共转染到细胞中。测试的子单元将是 利用分子生物学技术在GT1-7细胞中鉴定出哪些mRNAs 技巧。最后，将对重组GABA-A受体进行测试，以确定 静脉注射气体直接激活所需的亚基(具体目标3)。 在未来，建立了GABA-A的亚基特异性 受体被GABA和IV GAs直接激活，并被IV GAs调制， 这些将与类似动作的亚基专一性进行比较 在这个受体上的挥发性物质。对亚单位的理解 GAS对GABA-A受体调控的特异性及其分布 大脑中的这些亚单位可能暗示着与麻醉有关的区域。一次 确定了天然气的目标地点(S)，可能会开发更多 有效且更安全的制剂。

GABA-A receptors are modulated by many intravenous general anesthetics (IV GAs), at clinically relevant doses. Low concentrations of IV GAs, such as the anesthetic steroids, barbiturates and propofol, potentiate GABA responses in neurons. Higher concentrations, present in blood during total IV anesthesia, directly activate GABA-A receptors opening Cl- channels and thus reducing neuronal excitability. This represents a mechanism by which some IV GAs may achieve anesthesia. GABA-A receptors are heterogeneous consisting of five subunits. Each subunit could be one of fifteen varieties cloned so far. Using the patch- clamp technique to record GABA responses from single cells, GABA-A receptors with different subunit combinations have been found to possess distinct pharmacological properties. Preliminary data indicate that GABA-A receptor combinations, expressed by the neuronal GT1-7 cell line are not directly activated by high concentrations of IV GAs. To study the subunit specificity of GABA-A receptor modulation and activation by IV GAs, GABA-A receptor subunit cDNAs will be transfected into cell lines lacking endogenous receptors. The cells will first be transfected with homomeric receptors. These will be tested using the patch-clamp technique to determine whether homomeric receptors are functional (Specific Aim l). Having determined the subunits required for a receptor to respond to GABA, the subunits needed for potentiation of GABA-responses by IV GAs will be investigated (Specific Aim 2). If additional subunits are required for functional receptors, or modulation of GABA-A receptors by IV GAs, these will be co-transfected into cells. The subunits tested will be those for which mRNAs have been identified in GT1-7 cells using molecular techniques. Finally, recombinant GABA-A receptors will be tested to define the subunits required for direct activation by IV GAs (Specific Aim 3). In future, having established the subunit specificities for GABA-A receptor direct activation by GABA and IV GAs, and modulation by IV GAs, these will be compared to the subunit specificity for the similar actions of volatile agents at this receptor. An understanding of the subunit specificity of GABA-A receptor modulation by GAs and the distribution of these subunits in the brain may suggest areas involved in anesthesia. Once the target site(s) for GAs are defined it may be possible to develop more efficacious and safer agents.