Protective effects of epoxypukalide on pancreatic β-cells and glucose metabolism in STZ-induced diabetic mice

Diabetes is a consequence of a decrease on functional β-cell mass. We have recently demonstrated that epoxypukalide (Epoxy) is a natural compound with beneficial effects on primary cultures of rat islets. In this study, we extend our previous investigations to test the hypothesis that Epoxy protects β-cells and improves glucose metabolism in STZ-induced diabetic mice. We used 3-months old male mice that were treated with Epoxy at 200 μg/kg body weight. Glucose intolerance was induced by multiple intraperitoneal low-doses of streptozotocin (STZ) on 5 consecutive days. Glucose homeostasis was evaluated measuring plasma insulin levels and glucose tolerance. Histomorphometry was used to quantify the number of pancreatic β-cells per islet. β-cell proliferation was assessed by BrdU incorporation, and apoptosis by TUNEL staining. Epoxy treatment significantly improved glucose tolerance and plasma insulin levels. These metabolic changes were associated with increased β-cell numbers, as a result of a two-fold increase in β-cell proliferation and a 50% decrease in β-cell death. Our results demonstrate that Epoxy improves whole-body glucose homeostasis by preventing pancreatic β-cell death due to STZ-induced toxicity in STZ-treated mice.