Hypoglycemic effects of Zanthoxylum alkylamides by enhancing glucose metabolism and ameliorating pancreatic dysfunction in streptozotocin-induced diabetic rats

This study aimed to evaluate the hypoglycemic effect of Zanthoxylum alkylamides and explore the potential mechanism in streptozotocin (STZ)-induced diabetic rats. Diabetic rats were orally treated with 3, 6, and 9 mg per kg bw alkylamides daily for 28 days. As the alkylamide dose increased, the relative weights of the liver and kidney, fasting blood glucose, and fructosamine levels were significantly decreased. The alkylamides also significantly increased the body weight and improved the oral glucose tolerance of the rats. Likewise, the alkylamides significantly increased the levels of liver and muscle glycogen and plasma insulin. These substances further alleviated the histopathological changes in the pancreas of the diabetic rats. The beneficial effects of high-dose alkylamides showed a comparable activity to the anti-diabetic drug glibenclamide. Western blot and real-time PCR results revealed that the alkylamide treatment significantly decreased the expression levels of the key enzymes (phosphoenolpyruvate caboxykinase and glucose-6-phosphatase) involved in gluconeogenesis and increased the glycolysis enzyme (glucokinase) in the liver, and enhanced the expression levels of pancreatic duodenal homeobox-1, glucokinase, and glucose transporter 2 in the pancreas. In addition, it was also observed that the alkylamides, unlike glibenclamide, increased the transient receptor potential cation channel subfamily V member 1 and decreased cannabinoid receptor 1 expressions in the liver and pancreas. Therefore, alkylamides can prevent STZ-induced hyperglycemia by altering the expression levels of the genes related to glucose metabolism and by ameliorating pancreatic dysfunction.