MOLECULAR AND CELLULAR NEUROPHYSIOLOGY OF BUTYROLACTONES & RELATED COMPOUNDS

GABA-A受体/离子载体复合体负责最快 哺乳动物大脑中的抑制作用。这种受体的激活增加 穿过神经细胞质膜的氯离子通量，通常 超极化使神经元超极化，并降低放电作用的概率 潜力。几个调节位点可以改变GABA对 这种受体/离子载体复合体是在过去十年中发现的。 作用于这些部位并减少GABA诱导电流的药物是 通常是惊厥药；相反，增强GABA电流的药物是 通常是抗惊厥药。我们对印防己毒素特别感兴趣 位点(S)及其被一系列伽马丁内酯的调节 是在我们的实验室里合成的。我们之前已经表明， 不同的丁内酯替代品可增强(“GABA+”)或阻断 (“GABA-”)GABA诱导的氯电流。 在本项目的电生理学核心项目应用中，我们计划 致： 1.描述似乎有希望的新的伽马-丁内酯为 临床抗惊厥药。我们对研究特别感兴趣 化合物黄曲霉的衍生物，几乎是1000倍以上 比其他γ-丁内酯更有效地增强GABA诱导 洋流。我们还将研究内酯光学异构体，它可能是 对这个网站来说更有力，更有选择性。 2.明确这些化合物的具体作用机理(S)。我们 我相信这些化合物在M2中的两个不同位置起作用 GABA-A亚基的跨膜片段。我们将使用多种类型的 GABA-A受体亚单位突变体试图证实这一点。我们还将 研究花生四烯酸可能是一种天然配体的假设 为了这个网站。 3.评估这类离子通道对其他离子通道的调制 化合物。我们已经知道某些内酯会增强尼古丁 海马神经元的胆碱能电流。基于序列同源性 对于GABA-A受体亚单位，我们预计甘氨酸、5-羟色胺和 由Pi1-GABA亚基组成的同构体受体也应该对 伽马丁内酯。 计划中的实验将使用标准的电生理技术 大鼠神经元GABA-A受体和抑制电流的特征 以及转染肾细胞系的受体亚基。我们预计 这项工作对一些医学上的， 神经性和精神性疾病，尤指癫痫。

The GABA-A receptor/ionophore complex is responsible for most fast inhibition in the mammalian brain. Activation of this receptor increases the flux of chloride across the neuronal plasma membrane, which typically hyperpolarizes the neuron and diminishes the probability of firing action potentials. Several modulatory sites that modify the effect of GABA on this receptor/ionophore complex have been identified over the last decade. Drugs that act at these sites and diminish GABA-induced currents are usually convulsants; conversely, drugs that potentiate GABA currents are often anticonvulsants. We are particularly interested in a picrotoxin site(s) and its modulation by a series of gamma-butyrolactones that have been synthesized in our laboratories. We have previously shown that different substitute butyrolactones can either enhance ("GABA+") or block ("GABA-") GABA-induced chloride currents. In the electrophysiology core of this program project application, we plan to: 1. Characterize new gamma-butyrolactones that appear to have promise as clinical anticonvulsants. We are particularly interested in studying derivatives of the compound aflatrem, which is almost 1000 times more potent than other gamma-butyrolactones in augmenting GABA-induced currents. We shall also investigate lactone optical isomers, which may be more potent and selective for this site. 2. Define the detailed mechanism(s) of action of these compounds. We believe these compounds act at two distinct sites that are within the M2 transmembrane segment of the GABA-A subunits. We shall use a variety of GABA-A receptor subunit mutants to attempt to confirm this. We shall also investigate the hypothesis that arachidonic acid may be a natural ligand for this site. 3. Evaluate the modulation of other ion channels by this class of compounds. We already know that certain lactones potentiate nicotinic cholinergic currents in hippocampal neurons. Based on sequence homology with the GABA-A receptor subunits, we expect that glycine, serotonin, and homomeric receptors composed of pi1 GABA subunits should also respond to gamma-butyrolactones. The planned experiments will use standard electrophysiological techniques to characterize GABA-A receptors and inhibitory currents in rat neurons and also receptor subunits transfected into a kidney cell line. We expect this work to have therapeutic implications for a number of medical, neurological, and psychiatric diseases, especially epilepsy.