Exendin-4 Suppresses Src Activation and Reactive Oxygen Species Production in Diabetic Goto-Kakizaki Rat Islets in an Epac-Dependent Manner

摘要

Objective-reactive oxygen species (ros) is one of most important factors in impaired metabolism secretion coupling in pancreatic β-cells. We recently reported that elevated ros production and impaired atp production at high glucose in diabetic goto-kakizaki (gk) rat islets are effectively ameliorated by src inhibition, suggesting that src activity is upregulated. In the present study, we investigated whether the glucagon-like pep tide-1 signal regulates src activity and ameliorates endogenous ros production and atp production in gk islets using exendin-4. Research design and methods-isolated islets from gk and control wistar rats were used for immunoblotting analyses and measurements of ros production and atp content. Src activity was examined by immunoprecipitation of islet ly-sates followed by immunoblotting. Ros production was measured with a fluorescent probe using dispersed islet cells. Results-exendin-4 significantly decreased phosphorylation of src tyr416, which indicates src activation, in gk islets under 16.7 mmol/1 glucose exposure. Glucose-induced ros production (16.7 mmol/l) in gk islet cells was significantly decreased by coexposure of exendin-4 as well as pp2, a src inhibitor. The src kinase-negative mutant expression in gk islets significantly decreased ros production induced by high glucose. Exendin-4, as well as pp2, significantly increased impaired atp elevation by high glucose in gk islets. The decrease in ros production by exendin-4 was not affected by h-89, a pka inhibitor, and an epac-specific camp analog (8cpt-2me-camp) significantly decreased src tyr416 phosphorylation and ros production. Conclusions-exendin-4 decreases endogenous ros production and increases atp production in diabetic gk rat islets through suppression of src activation, dependency on epac. Diabetes 60:218-226, 2011