Effect of Zanthoxylum alkylamides on glucose metabolism in streptozotocin-induced diabetic Sprague-Dawley rats

This research aimed at investigating the hypoglycemic effect of Zanthoxylum alkylamides and whether TRPV1 receptor could participate in the glucose metabolism by using streptozotocin-induced diabetic rat model. The results showed that the blood glucose measured in the Zanthoxylum alkylamides treated group (ALK) showed significantly lower values than that in the model group (Model). Significant improvements in the oral glucose tolerance as well as plasma insulin and hepatic glycogen were also observed in the ALK group, when compared to the model group. However, the improving effects of Zanthoxylum alkylamides on glucose metabolism disorder in diabetic rats were markedly inhibited by capsazepine as the TRPV1 receptor antagonist. In addition, there were significant differences in the levels of mRNA and protein of phosphoenolpyruvate carboxylase (PEPCK), gucose-6-phosphatase (G6Pase), glucokinase (GK) and cannabinoid receptor l (CB1) in the livers of the ALK group compared to model group. Meanwhile, ALK group also exhibited a remarkable increase in the pancreatic-duodenal homeobox 1 (PDX-1), glucose transporter 2 (GLUT 2), GK levels and a significant decrease in the expression levels of CB1 in the pancreas, while the presence of capsazepine would affected the expression of these genes. These findings indicate that Zanthoxylum alkylamides could ameliorate the glucose metabolism disorder in diabetic rats. Furthermore, the TRPV1 receptor could participate in regulating the expressions of genes and proteins related to glucose metabolism and insulin secretion in the liver and pancreas, and takes a role in the hypoglycemic process of Zanthoxylum alkylamides.