Resistin is produced by rat pancreatic islets and regulates insulin and glucagon in vitro secretion

ABSTRACT Resistin participates in the regulation of energy homeostasis, insulin resistance, and inflammation. The potential expression in pancreas, and modulation of the endocrine pancreas secretion by resistin is not well characterized, therefore, we examined it on several levels. We examined the localization of resistin in rat pancreatic islets by immunohistochemistry and immunofluorescence, and the potential presence of resistin mRNA by RT-PCR and protein by Western Blot in these structures. In addition, we studied the regulation of insulin and glucagon secretion by resistin in pancreatic INS-1E β- and InR-G9 α-cell lines as well as isolated rat pancreatic islets. We identified resistin immunoreactivity in the periphery of rat pancreatic islets and confirmed the expression of resistin at mRNA and protein level. Obtained data indicated that resistin is co-localized with glucagon in pancreatic α-cells. In addition, we found that in vitro resistin decreased insulin secretion from INS-1E cells and pancreatic islets at normal (6 mM) and high (24 mM) glucose concentrations, and also decreased glucagon secretion from G9 cells and pancreatic islets at 1 mM, whereas a stimulation of glucagon secretion was observed at 6 mM glucose. Our results suggest that resistin can modulate the secretion of insulin and glucagon from clonal β or α cells, and from pancreatic islets.