Volatile Anesthesia and the GABAA Receptor Gamma Subunit

描述(申请人提供)：挥发性麻醉剂是广泛使用的药物，可产生显著的毒性作用，但其分子靶点和作用机制尚不清楚。我们研究的总体目标是确定神经系统中吸入麻醉剂起作用的关键分子位置。为了设计出更具特异性的药物，以达到理想的效果和更少的毒副作用，需要这些信息。γ-氨基丁酸A型受体(GABAA)可能是重要的麻醉靶点。哺乳动物大脑中的大多数GABAA受体由α、β和伽马亚基组成。分子研究，主要是使用缺乏伽马亚基的表达的GABAA受体，已经确定了似乎对挥发性麻醉药的调节至关重要的位置。然而，我们发现，与非伽马亚基的受体相比，将伽马亚基整合到表达的GABAA受体中既降低了对挥发性麻醉剂的敏感性，又基本上抵消了假定的挥发性麻醉剂位点突变对阿尔法亚基的影响(αS2701)。我们的工作假设是，伽马亚基包含调节挥发性麻醉剂对GABAA受体的作用的特定结构特征。我们建议1)确定在存在和不存在挥发性麻醉药的情况下伽马亚基对GABAA受体功能的影响，2)定位伽马亚基对调节挥发性麻醉作用至关重要的部分，以及3)确定亚基如何改变推测的阿尔法亚基麻醉部位突变的影响。

DESCRIPTION (provided by applicant): Volatile anesthetics are widely utilized drugs that can produce significant toxic effects, yet their molecular targets and mechanisms of action are poorly defined The overall aim of our research is to identify critical molecular sites in the nervous system where inhaled anesthetics act. This information is needed in order to design drugs with greater specificity for desirable actions and fewer toxic side-effects. The gamma-aminobutyric acid type A (GABAA) receptor is likely an important anesthetic target. Most GABAA receptors in mammalian brain are composed of alpha, beta, and gamma subunits. Molecular studies, largely obtained using expressed GABAA receptors lacking gamma subunits, have identified sites that appear critical for modulation by volatile anesthetics However, we have found that incorporation of gamma subunits into expressed GABAA receptors both reduces sensitivity to volatile anesthetics compared with gamma-less receptors, and essentially nullifies the impact of a mutation at the putative volatile anesthetic site on the alpha subunit (alpha S2701) Our working hypothesis is that the gamma subunit contains specific structural features that modulate volatile anesthetic actions on GABAA receptors. We propose to 1) ascertain the impact of the gamma subunit on GABAA receptor function in the presence and absence of volatile anesthetics, 2) locate portions of the gamma subunit that are critical for modulation of volatile anesthetic actions, and 3) determine how the subunit alters the effects of mutations at the putative alpha subunit anesthetic site.