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GABA_(B)受体与腺苷酸环化酶偶联环节的脱敏研究

俞在芳, 程冠军, 胡本荣

上海医科大学医学神经生物学国家重点实验室.上海 200032；中山医科大学肿瘤研究所.广东,广州 510089；中山医科大学药理教研室.广东,广州 510089

摘要

将突触体膜与佛波酯(PMA)、GABA_(B)受体激动剂巴氯芬(BAL)预孵育一定时间后,BAL对腺苷酸环化酶(AC)基础活性及forskolin刺激的AC活性的抑制率显著降低(脱敏);而forskolin预孵育时,BAL对基础及forskolin刺激的AC活性的抑制率不变,表明GABA_(B)受体与AC偶联环节的脱敏机制涉及蛋白激酶C(PKC)激活,而与蛋白激酶A无关,脱敏时GABA_(B)受体的K_(d)值增加。

关键词： GABA_(B)受体; 腺苷酸环化酶; 脱敏; 蛋白激酶C

Studies on desensitization of GABA_(B) receptor coupled adenylate cyclase

Yu Zaifang, Cheng Guanjun, Hu Benrong

State Key Laboratory of Medical Neurobiology, Shanghai Medical University.Shanghai 200032；China

Abstract

After preincubation of crude synaptic membranes (P_(2)membranes)with phorber ester(PMA) or GABA_(B) receptor agonist baclofen (BAL), the rate of inhibition of BAL on basal adenylate cyclase (AC) activity and forskolin-stimulated AC activity significantly reduced (desensitized). This effect of BAL did not change after preincubation with forskolin suggesting that the desenstitization mechanism of GABA_(B) receptor coupled AC is related with activation of protein kinase C (PKC), but not with protein kinase A .It was further found that the equilibrium dissociation constant (Kd) of GABA_(B) receptor was increased during desensitization. Our results suggest that PKC activation may cause some structural or conformational changes of GABA_(B) receptor, resulting in an uncoupling from G protein and desensitization of GABA_(B) receptor-coupled AC.

Key words: GANA_(B);Receptor;Adenylate cyclase;Desensitization

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引用本文：

俞在芳, 程冠军, 胡本荣. GABA_(B)受体与腺苷酸环化酶偶联环节的脱敏研究[J]. 生理学报 1997; 49 (1): .

Yu Zaifang, Cheng Guanjun, Hu Benrong. Studies on desensitization of GABA_(B) receptor coupled adenylate cyclase. Acta Physiol Sin 1997; 49 (1): (in Chinese with English abstract).