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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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Citing This Article：

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).