Decrease in functional activity of G-proteins hormone-sensitive adenylate cyclase signaling system, during experimental type II diabetes mellitus

Author: Shpakov A.   Kuznetsova L.   Plesneva S.   Bondareva V.   Gur’yanov I.   Vlasov G.   Pertseva M.  

Publisher: Springer Publishing Company

ISSN: 0007-4888

Source: Bulletin of Experimental Biology and Medicine, Vol.142, Iss.6, 2006-12, pp. : 685-689

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Abstract

The development of experimental type II diabetes mellitus in rats was accompanied by dysfunction of inhibitory and stimulatory heterotrimeric G-proteins, components of hormone-sensitive adenylate cyclase signal system. The function of inhibitory G-proteins decreased most significantly under these conditions, which is seen from weakened regulatory effects of somatostatin (in the myocardium) and bromocriptine (in the brain striatum) realized via inhibitory G-proteins in diabetic rats compared to controls. These hormones produce less pronounced inhibitory effect on forskolin-induced activation of adenylate cyclase. In the myocardium of diabetic rats, the stimulatory effects of isoproterenol and relaxin on adenylate cyclase realized via stimulatory G-proteins were decreased to a lesser extent. In the striatum of diabetic rats the stimulatory effect of serotonin and relaxin did not differ from the control. Therefore, dysfunction of stimulatory G-proteins during type II diabetes mellitus is characterized by tissue specificity. Synthetic peptides corresponding to functionally important regions in α-subunits of G-proteins and relaxin receptor LGR7 less effectively inhibited hormone signal transduction via the adenylate cyclase system in rats with type II diabetes. These changes reflect abnormal coupling between receptors and G-proteins in tissues of diabetic rats.

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