RECEPTOR-MEDIATED INHIBITION OF ADENYLATE CYCLASE

本研究计划的长期目标是深入了解 受体抑制腺苷酸环化酶活性的作用机制。 许多神经元受体，包括阿片类，D-2多巴胺能， 据信α 2-肾上腺素能、嘌呤能和胆碱能调节 通过抑制腺苷酸环化酶的神经活性。 由于这些受体 在调节大脑功能，洞察力， 了解它们的作用机制， 涉及这些受体的神经系统疾病的治疗。 近日一 药理学性质与脑相似的μ-阿片受体 在泌乳素分泌细胞上发现了μ阿片受体， 肿瘤编号7315c。 初步结果表明，这种受体是 与抑制性GTP结合蛋白（称为Ni）相关， 作为抑制性受体和腺苷酸环化酶之间的转换器。 的 这项研究的具体目的是确定如何穆阿片 受体增强鸟苷酸与镍的相互作用。 是 假设μ-阿片受体的激活增强了 GDP与GTP的交换。 最初，将测试阿片类药物的 能够刺激7315c膜中的GT3活性。 接下来，GDP将 测试其阻断Gpp（NH）p-和GTP-诱导的 Ni的活化。 还将测试阿片激动剂的能力， 增强Gpp（NH）p从Ni中的去除，并引起Gpp（NH）p的可预测变化。 腺苷酸环化酶活性。 最近有人提出百日咳毒素 诱导Ni的ADP核糖基化，导致Ni的解偶联， 抑制性受体 百日咳毒素将被测试其能力， 在Ni处阻断μ-阿片受体介导的鸟苷酸交换。 它 还将确定百日咳毒素是否对 抑制性受体 中叶膜含有抑制性 D-2多巴胺受体将与百日咳毒素处理，然后融合 7315c膜（不含D-2受体）。 D-2多巴胺 然后将测试受体与Ni再偶联的能力， 抑制腺苷酸环化酶。 最后，将使用阿片亲和柱 在试图分离出与神经元紧密相关的μ-阿片受体时， 倪

The long term objective of this research plan is to gain insight into the mechanism of action of receptors inhibiting adenylate cyclase activity. Numerous neuronal receptors including opiate, D-2 dopaminergic, alpha2-adrenergic, purinergic, and cholinergic are believed to modulate neuronal activity by inhibiting adenylate cyclase. Since these receptors play a critical role in modulating the functioning of the brain, insight into their mechanism of action is fundamental to the understanding and treatment of neurological disorders involving these receptors. Recently, a Mu-opiate receptor with pharmacological properties similar to brain Mu-opiate receptors was discovered on the cells of a prolactin secreting tumor termed 7315c. Preliminary results suggest that this receptor is associated with the inhibitory GTP binding protein, termed Ni, which acts as a transducer between the inhibitory receptor and adenylate cyclase. The specific aim of this research proposal is to determine how the Mu-opiate receptor enhances the interaction of guanyl nucleotides with Ni. It is hypothesized that activation of the Mu-opiate receptor enhances the exchange of GDP for GTP at Ni. Initially, opiates will be tested for their ability to stimulate GTPase activity in 7315c membranes. Next, GDP will be tested for its ability to block both the Gpp(NH)p- and the GTP-induced activation of Ni. Opiate agonists will also be tested for their ability to enhance the removal of Gpp(NH)p from Ni and cause predictable changes in adenylate cyclase activity. Pertussis toxin has recently been proposed to induce an ADP ribosylation of Ni resulting in the uncoupling of Ni and inhibitory receptors. Pertussis toxin will be tested for its ability to block Mu-opiate receptor-mediated exchange of guanyl nucleotides at Ni. It will also be determined if pertussis toxin has a direct effect on inhibitory receptors. Intermediate lobe membranes containing an inhibitory D-2 dopamine receptor will be treated with pertussis toxin and then fused with 7315c membranes (which contain no D-2 receptor). The D-2 dopamine receptor will then be tested for its ability to recouple with Ni and inhibit adenylate cyclase. Finally, an opiate affinity column will be used in an attempt to isolate the Mu-opiate receptor in close association with Ni.