Expression and function of GIP receptor in brown adipocytes

After differentiated primary brown fat cells were incubated with glucose-dependent insulinotropic polypeptide(GIP), GIP receptor(GIPR), uncoupling protein 1(UCP-1), and CREB protein expressions were measured by Western blot, and intracellular cAMP was detected by ELISA. The results showed that cultured primary adipocytes manifested a typical morphology of brown fat cells, with a large amount of lipid droplet accumulation shown by oil red O and UCP-1 expression detected by immunohistochemistry. On the later stage of brown adipocyte differentiation, GIPR mRNA expression revealed an increased tendency. GIPR protein expression was detected by immunohistochemistry in brown fat cells. 1 and 100 nmol/L GIP significantly increased GIPR, UCP-1, and CREB protein expressions while 10 nmol/L GIP decreased the expressions of these genes. Treatment with various concentrations of GIP for 24 hours raised cAMP concentrations in brown fat cells. These results suggest that GIPR plays a critical role in the differentiation course of primary brown adipocyte. (Chin J Endocrinol Metab, 2016, 32: 857-861) Key words: Diabetes mellitus, type 2; Brown adipose tissue; Glucose-dependent insulinotropic polypeptide receptor