Rapamycin induces autophagy and exacerbates metabolism associated complications in a mouse model of type 1 diabetes.

Type 1 diabetes mellitus (T1DM) is characterized by lack of insulin production as a consequence of massive beta cells destruction. The contributions of autophagy to loss of beta cell mass were not clearly elucidated. Rapamycin is a specific and potent inhibitor of mammalian target of rapamycin (mTOR) and is used as the central immunosuppressant in T1DM patients especially for those who received islet transplantation. In the present study, effects of rapamycin on autophagy of T1DM were investigated in a mouse model treated with multiple low doses of streptozotocin. Rapamycin treatment led to hyperglycemia, weight loss, increased intake of food and drinking water, and islet inflammation in T1DM mice. Pathological changes including autophagy and apoptosis in pancreas, kidney, spleen and thymus, accompanied with an accumulation of LC3-II, Beclin1 and Caspase-3 protein were observed. The results indicate that rapamycin may exacerbate metabolism associated complications by activating autophagy and apoptosis in T1DM.