REGULATION OF OPIOID RECEPTORS IN BRAIN BY GTP

该提案旨在确定鸟苷酸之间的关系 和阿片受体的功能。 该提案源于我们的 最近证明了特定的阿片刺激的GT3活性在脑中 以及一个新出现的概念框架， 神经递质与环磷酸腺苷负或正偶联 生产对GTP有绝对的要求，而且， GTP通过GTP酶水解为GDP终止激素之间的偶联 和腺苷酸环化酶。 拟议工作的主要目标是测试 假设GTP调节某些类别的细胞之间的偶联， 阿片受体及其最近证实的腺苷酸抑制 大鼠脑环化酶。 这项工作的重点是GTP结合蛋白 复合物，Ni，被认为是介导受体之间的耦合 及其效应器。 镍蛋白的两个特性-- GTP水解， 其使激素和腺苷酸环化酶之间的偶联失活 系统和GTP的GDP交换，重新激活耦合机制 将被衡量。 药理学特征研究和 这两个参数在脑中的动力学可以回答以下问题： 阿片样物质受体亚型与腺苷酸环化酶有关，并且还可以 表明N蛋白调节其他受体亚型， 腺苷酸环化酶 这些研究将确定阿片受体亚型， 新的方式，从根本上不同于和补充， 基于受体结合的阿片受体亚型的当前概念 问题研究 预计脑啡肽偏好“δ”受体 是与腺苷酸环化酶相关的亚型之一， 通过GTP。 使用放射性标记的配体在条件下测量受体结合 GTP水解条件有望解决明显的差异 阿片类药物刺激GT3的效力较低， 它们与受体的结合。 阿片类药物刺激的GTdR检测 和GTP-GDP交换在耐受依赖动物可能表明新的 基于Ni蛋白的阿片成瘾的方法。

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.