REGULATION OF OPIOID RECEPTORS IN BRAIN BY GTP

这项提议试图定义鸟苷核苷酸之间的关系 和阿片受体在大脑中的功能。这项建议源自我们的 阿片类药物刺激脑内特异性GTP酶活性的研究进展 再加上一个新兴的概念框架，表明 与环磷酸腺苷负或正偶联的神经递质 生产对GTP有绝对要求，此外， GTP酶将GTP水解为GDP终止激素间的偶联 和腺苷环化酶。拟议工作的主要目标是测试 GTP调节某一类药物之间的耦合的假设 阿片受体及其对腺苷的抑制作用 环化酶在大鼠脑中的表达。这项工作的重点是GTP结合蛋白 镍，被认为是介导受体之间偶联的复合体 以及它的效应器。镍蛋白的两个性质--GTP水解， 使激素和腺苷环化酶之间的偶联失活 GDP交换的制度和GTP，这重新激活了耦合机制 --将被衡量。药理概况及药理研究进展 这两个参数在大脑中的动力学可以回答以下问题 阿片受体亚型(S)与腺苷环化酶有关，进一步可能 提示N蛋白对其他受体亚型的调节不与 腺苷环化酶。这些研究将确定阿片受体亚型 新的、从根本上不同于 基于受体结合的阿片受体亚型研究现状 学习。据推测，偏爱脑啡肽的“Delta”受体 将是与腺苷环化酶相连的亚型之一，因此受到调节 由GTP提供。用放射性标记配基测量受体结合 GTP的水解条件有望解决这一明显的差异 阿片类药物刺激GTP酶的效力低于 它们与受体的结合。阿片类药物刺激的GTP酶的检测 而耐受依赖动物的GTP-GDP交换可能表明新的 基于Ni蛋白的阿片成瘾研究进展。

This proposal seeks to define the relationship between guanyl nucleotides and opiate receptor function in brain. The proposal derives from our recent demonstration of specific opiate-stimulated GTPase activity in brain together with an emerging conceptual framework suggesting that neurotransmitters coupled either negatively or positively to cyclic AMP production have an absolute requirement for GTP and, further, that the hydrolysis of GTP to GDP by GTPase terminates the coupling between hormones and adenylate cyclase. The primary goal of the proposed work is to test the hypothesis that GTP regulates the coupling between a certain class of opioid receptors and its recently demonstrated inhibition of adenylate cyclase in rat brain. The work is focused on the GTP-binding protein complex, Ni, that is thought to mediate the coupling between the receptor and its effector. Two properties of the Ni protein -- GTP hydrolysis, which inactivates the coupling between hormone and the adenylate cyclase system and GTP for GDP exchange, which reactivates the coupling mechanism -- will be measured. Investigation of the pharmacological profile and kinetics of these two parameters in brain may answer the question of which opioid receptor subtype(s) is linked to adenylate cyclase and, further, may suggest regulation by N proteins of other receptor subtypes not linked to adenylate cyclase. These studies will define opioid receptor subtypes in a manner that is new, fundamentally different from and complementary to the current concepts of opioid receptor subtypes based on receptor binding studies. It is expected that the enkephalin-preferring "delta" receptor will be one of the subtypes linked to adenylate cyclase and thus regulated by GTP. Measurement of receptor binding using radiolabeled ligands under GTP hydrolytic conditions is expected to resolve the apparent discrepancy between the lower potency of opioids for stimulating GTPase compared with their binding to receptors. The examination of opioid-stimulated GTPase and GTP-GDP exchange in tolerant-dependent animals may suggest new approaches to opiate addiction based on the Ni protein.