Objective To explore the effect of transcutaneous auricular vagus nerve stimulation(taVNS) on blood glucose regulation and the expression of insulin receptors(INR) of hypothalamus

liver and skeletal muscle tissues in impaired glucose tolerance(IGT) rats

so as to reveal its mechanisms underlying improvement of IGT. Methods Thirty-six male Wistar rats were randomly divided into control

model

transcutaneous auricular none-vagus nerve stimulation(tnVNS)

and taVNS groups(n=9 in each group). The IGT model was established by feeding the rats with high-fat and high-sugar diet for 5 weeks

and subsequent intraperitoneal injection of a dose of streptozotocin(20 mg/kg). Transcutaneous electrostimulation(2 mA

2 Hz/15 Hz) was applied to auricular concha(taVNS) or auricular margin(tnVNS)

respectively. The treatment was conducted for 30 min once daily for 4 weeks. The body weight

fasting plasma glucose(FPG)

2 h plasma glucose(2 h PG) were recorded every week. The contents of plasma insulin(INS)

glucagon(GC)

glycosylated hemoglobin(GHbA1 c) were detected by using enzyme linked immunosorbent assay(ELISA). The expression levels of INR in hypothalamus

liver and skeletal muscle tissues were detected by Western blot. Results After modeling

the rats' body weight

the contents of FPG

2 h PG

GC and GHbA1 c were significantly up-regulated(P<0.001

P<0.05

P<0.01)

and the content of INS and expression of INR in hypothalamus

liver and skeletal muscle tissues were significantly down-regulated in the model group compared with the control group(P<0.001

P<0.01

P<0.05). Following the treatment

the increased FPG

2 h PG

GC

and the decreased INS and INR expression of hypothalamus

liver and skeletal muscle tissues were apparently reversed in the taVNS group relevant to the model group(P<0.001

P<0.01

P<0.05). Compared with the tnVNS group

the FPG and 2 h PG contents were considerable decreased

and the content of INS and INR expression of hypothalamus and liver were obviously increased in the taVNS group(P<0.001

P<0.05

P<0.01). Conclusion taVNS can improve the blood glucose and insulin sensitivity in IGT rats

which may contribute to its effectiveness in up-regulating the expression of INR in hypothalamus

liver and skeletal muscle tissues.