Abstract: Objective To investigate effects of Jiangtang Sanhuang tablet (JTSHT) for regulating blood glucose and alleviating islet cell damage in db/db mice and its protective effects against endoplasmic reticulum stress (ERS) and autophagy induced by glycolipid toxicity. Methods Forty db/db mice were randomized into 4 groups for daily intragastric administration of saline, JTSHT of 2.64 and 1.32 g/kg, and metformin at 0.225g/kg for 8 weeks, using 10 C57BL/6J mice as the normal control. After the treatments, the metabolic indexes of the mice were measured, and morphological changes of the islet cells were observed. A mouse islet cell line (MIN6) was exposed to high glucose (22 mmol/L glucose) and 0.1 mmol/L palmitic acid, followed by treatment with the sera from JTSHT- or saline- treated SD rats, alone or in combination with SP600125, and the changes in cell apoptosis, ERS and autophagy were evaluated using flow cytometry, RT-qPCR and Western blotting. Results In db/db mice, treatment with JTSHT significantly improved glucose and lipid metabolism (P<0.05) and suppressed progressive weight gain (P<0.05) without significant effect on drinking water volume (P>0.05). JTSHT was also found to promote repair of islet cell injuries. In the cell experiments, high glucose exposure significantly increased apoptosis rate of MIN6 cells (P<0.05), which was obviously lowered by treatment with JTSHT-treated rat serum (P<0.05). Western blotting showed that JTSHT significantly reduced the level of ERS and autophagy caused by glycolipid toxicity in MIN6 cells (P<0.05). Interference with ERS using SP600125 significantly attenuated the protective effect of JTSHT against MIN6 cell injury, apoptosis and autophagy induced by glycolipid toxicity (P<0.05). Conclusion JTSHT has protective effects against glycolipid toxicity in MIN6 cells possibly by inhibiting ERS and autophagy.

Key words: Jiangtang Sanhuang tablets; diabetes; islet cells; endoplasmic reticulum stress; autophagy