Modulatory effect of berberine on adipose tissue PPARγ, adipocytokines and oxidative stress in high fat diet/ streptozotocin-induced diabetic rats

The current study was designed to investigate the anti-hyperglycemic and antioxidant effects of berberine (BBR) in high fat diet/streptozotocin (HFD/STZ)-induced type 2 diabetic rats, focusing on the role of adipose tissue peroxisome proliferator activated receptor gamma (PPARγ), resistin and inflammatory cytokines. Type 2 diabetes was induced by feeding rats with HFD for 4 weeks followed by a single intraperitoneal injection of 35 mg/kg body weight STZ. Diabetic rats were supplemented with 50 and 100 mg/kg BBR orally for 4 weeks. HFD/STZ-induced diabetic rats showed a significant increase in serum glucose and fructoseamine, and significant decrease in body weight and serum insulin. Serum pro-inflammatory cytokines were significantly increased in serum of the diabetic rats. BBR significantly ameliorated body weight, and serum glucose, insulin and pro-inflammatory cytokines. In addition, diabetic rats exhibited a significant increase in liver lipid peroxidation and nitric oxide levels, and declined antioxidant defenses, an effect that was reversed following treatment with BBR. Adipose tissue PPARγ mRNA was significantly down-regulated while resistin mRNA was markedly up-regulated in diabetic rats. BBR treatment significantly ameliorated both PPARγ and resistin mRNA expression. In conclusion, BBR attenuates hyperglycemia and its associated oxidative stress and inflammation, possibly through potentiation of the antioxidant defenses and up-regulation of PPARγ expression.