Effects of transcutaneous auricular vagus nerve stimulation on intestinal ligandins in a rat model of functional dyspepsia

Abstract

ObjectiveTranscutaneous auricular vagus nerve stimulation (taVNS) can relieve the symptoms of functional dyspepsia (FD) and improve the quality of life of patients, however, the mechanism underlying this effect remains unclear. Therefore, this study aimed to investigate the effects of taVNS on the expression of intestinal mucosal ligandins. MethodsThis study was conducted on 24 specific Spathogen-free Sprague–Dawley rats (12 males and 12 females). The rat model of FD was established by tail-clip stimulation. After FD was established successfully, all rats were randomized to either the normal group (n = 6), model group (n = 6), taVNS group (n = 6), or sham-taVNS group (n = 6). After two weeks of the respective intervention, the score of their general conditions, 3 h food intake, gastric emptying rate, and the histology of gastric antrum tissues were observed to evaluate modeling success, and then the effect of taVNS was evaluated. Western blotting was used to assess the expression of the tight junction ligandins —ZO-1 and occludin—and the adhesion ligandin—β-catenin—in the duodenum. The effect of taVNs on the expression of intestinal mucosal barrier ligandins—ZO-1, occludin, and β-catenin—in FD rats was preliminarily investigated. ResultsWhen the model-induced period was finished, the manifestations of FD in the model group rats were mental exhaustion, reduced activities, decreased score of the general conditions, and decreased 3 h food intake, compared to the normal group rats. In addition, minimal eosinophil infiltration, without any mucosal erosion or ulcer, was observed in the gastric antrum mucosa. At the end of the study, the mental state of the FD rats improved, and their activities and gastric emptying rate increased in the taVNS group rats. Compared to the normal rats, the duodenal mucosa had less expression of the tight junction ligandins ZO-1 and occludin, but β-catenin expression remained unchangedin the model rats. The expression of the tight junction ligandins ZO-1 and occludin were increased in the duodenal mucosa of model rats after the taVNS intervention. ConclusionTaVNS can improve the gastric motility and mental state of rats with FD. It may play a therapeutic role by improving the expression of the tight junction ligandin ZO-1 and occludin in the duodenal mucosa, while also repairing the duodenal mucosal barrier.