Hypericin maintians PDX1 expression via the Erk pathway and protects islet β-cells against glucotoxicity and lipotoxicity.

Abstract

A decrease in islet β-cell mass is closely associated with the development and progression of diabetes. Therefore, protection against β-cell loss is an essential measure to prevent and treat diabetes. In this study, we investigated the protective effects of non-photoactivated hypericin, a natural compound, on β-cells both in vitro and in vivo. In vitro, hypericin greatly improved INS-1 cell viability under high-glucose and high-fatty-acid conditions by inhibiting glucotoxicity- and lipotoxicity-induced apoptosis and nitric oxide (NO) production. Then, we further demonstrated that hypericin elicited its protective effects against glucotoxicity and lipotoxicity in INS-1 cells by attenuating the reduction in pancreatic duodenal homeobox-1 (PDX1) expression and Erk activity. In vivo, prophylactic or therapeutic use of hypericin inhibited islet β-cell apoptosis and enhanced the anti-oxidative ability of pancreatic tissue in high-fat/high-sucrose (HFHS)-fed mice, thus alleviating β-cell loss and maintaining or improving β-cell mass and islet size. More importantly, hypericin treatment decreased fasting blood glucose, improved glucose intolerance and insulin intolerance, and alleviated hyperinsulinaemia in HFHS-fed mice. Therefore, hypericin showed preventive and therapeutic effects against HFHS-induced onset of type II diabetes in mice. Hypericin possesses great potential for development as an anti-diabetes drug in the future.