Influence of propolis on oxidative stress, inflammation and apoptosis in streptozotocin-induced diabetic rats

Propolis is a complex mixture of several resinous substances which are collected from plants by honeybees. In the present study, an attempt has been made to evaluate the possible antioxidant effects of propolis on diabetes-induced oxidative stress, inflammation and apoptosis in rats. Diabetes was induced in male rats by intraperitoneal injection of a single dose (45mg/kg body weight) of streptozotocin (STZ). After induction of diabetes, rats were orally administered propolis in two separate doses, 50 or 100 mg/kg body weight daily for 6 weeks. Obtained results showed that administration of propolis remarkably decreased the oxidative stress resulting from diabetes induction, as reflected by lowered hepatic and pancreatic malondialdehyde (MDA) and protein carbonyl (PC) levels, and enhanced the antioxidant defense system capability by increasing hepatic and pancreatic contents of glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and total antioxidants (TAC), compared to the diabetic group. Also, treatment of diabetic rats with propolis significantly ameliorated the inflammatory disorders as indicated by markedly decreased serum inflammatory markers such as C-reactive protein (CRP), interleukin 10 (IL-10) and transformation growth factor ? (TGF-?), compared to the untreated diabetic rats. In addition, propolis was found to induce apoptosis and cell cycle arrest in diabetic rats, which was confirmed by increased pancreatic p53, caspase-3 and G0/G1; and decreased Bcl-2, compared to the diabetic group. Current findings provided additional evidence that propolis has antioxidant, anti-inflammatory and apoptotic properties which may be of health benefits in ameliorating various diabetes side effects.