Cooperation between galanin and insulin in facilitating glucose transporter 4 translocation in adipose cells of diabetic rats

Abstract

The glucose transporter 4 (GLUT4) translocation is a vital link of insulin-induced glucose uptake in adipose tissue and skeletal muscle. It is an important topic in anti-diabetic research to explore novel agents to facilitate the role of insulin. The aim of this study was to verify the hypothesis that neuropeptide galanin may enhance insulin-induced GLUT4 translocation to increase glucose uptake in adipose tissue of type 2 diabetic models. Insulin and/or galanin were injected respectively or cooperatively into type 2 diabetic rats once a day for fifteen days. The results showed that administration of galanin significantly enhanced insulin-induced GLUT4 and vesicle-associated membrane protein 2 (VAMP2) translocation, Akt phosphorylation and glucose uptake, but not GLUT4 mRNA and protein expression levels in adipose cells. The beneficial roles of galanin on insulin-induced events may be blocked by MK-2206, an Akt inhibitor, indicating that the Akt phosphorylation is essential for promoting impact of galanin on the insulin-induced events. These results suggest that galanin may benefit insulin-induced GLUT4 and VAMP2 translocation, and subsequent glucose uptake via the activated Akt-VAMP2-GLUT4 pathway in adipose cells. These findings deepen our understanding of the anti-diabetic effect of galanin and its mechanism.