RESUMO
OBJECTIVE: To observe the effects of transcutaneous auricular vagus nerve stimulation ï¼taVNSï¼ on plasma melatonin ï¼MLTï¼ content and insulin receptor expression in the liver, the skeletal muscles, and the pancreas of Zucker diabetic fatty ï¼ZDFï¼ rats, so as to explore the hypoglycemic mechanism of taVNS. METHODS: Thirty male ZDF rats were randomly divided into model group, taVNS group and sham-taVNS group, with 10 rats in each groupï¼ besides, 10 male Zucker lean rats of the same strain were collected for the blank control group. ZDF rats were fed with high-fat diet to induce type 2 diabetes mellitus ï¼T2DMï¼ rat model. In the taVNS group, HANS-100A electroacupuncture instrument was used to stimulate the cavum conchae of both sides. The stimulation sites of rats in the sham-taVNS were the same as the taVNS group, but without electricity delivered. The above interventions were performed 30 min each time, once daily, lasting for 6 weeks. Fasting blood glucose ï¼FBGï¼ was measured weekly in each group, the plasma metatonin ï¼MLTï¼ content was detected by ELISA, and the insulin receptor expression level in the liver, the skeletal muscle and the pancreas was determined by Western blot. RESULTS: Compared with the blank control group, the level of FBG of rats were increased ï¼P<0.01ï¼, the plasma MLT content was decreased ï¼P<0.01ï¼ and the insulin receptor expression level in the pancreatic tissue was decreased ï¼P<0.01ï¼ in the model group. In the taVNS gruop, FBG was decreased ï¼P<0.05, P<0.01ï¼, the plasma MLT content was increased ï¼P<0.01ï¼, and the insulin receptor expression level in the liver, the skeletal muscle and the pancreas was increased ï¼P<0.05, P<0.01, P<0.001ï¼ when compared with the model group. Compared with the taVNS group, FBG was increased ï¼P<0.05, P<0.01ï¼, the plasma MLT content was decreased ï¼P<0.01ï¼, and the expression level of insulin receptors in the skeletal muscle and the pancreas was decreased ï¼P<0.01, P<0.001ï¼ in the sham-taVNS group. CONCLUSION: The taVNS can improve the insulin resistance and ultimately obtain the antihyperglycemic effect through regulating MLT concentration.