Effects Of C-Fos Expression In Brain Stem And Gastric Acid Secretion Induced By Rwis In Rats With Ventromedial Hypothalamic Lesions

Ventromedial hypothalamic nucleus (VMH), located at the posterior hypothalamus, is important in the controlling of gastric functions, and is also known as the satiety center. It participated in the regulation of food intake, feeding and a variety of functions of mammalian. A large number of experiments confirmed that VMH played an important role in the regulation of the gastric motility and secretion. But the effects of VMH on the c-Fos expression in the brain stem (DMV, NTS, AP, NA) and gastric acid secretion induced by the restraint water-immersion stress ( RWIS ) have not been reported so far. In this study, we observed the effects after lesioning VMH on gastric acid secretion and c-Fos expression in the brain stem during the RWIS.This study was divided into three parts.The first part, we observed the effects after lesion of VMH on gastric acid secretion induced by RWIS. Electrolytic lesions were used in the study. The lesion parameters were: anode current of 2 mA, 20 s.The method of pylorus ligation was used to collect gastric acid. The pH value of the collected juice was measured by precision pH meter. Gastric ulcer index was expressed by erosion index (EI). Results: compared with the sham group, there was no difference on the volumes of gastric juice after lesioning VMH, but gastric acidity had a marked increase. Gastric ulcer index had a marked increase.The second part, we observed the effects of lesioning VMH on c-Fos expression in the brain stem(NTS, DMV, NA and AP ) during the RWIS. Results: compared with the sham group, lesioning VMH induced more intense c-Fos expression in the NTS,DMV and AP, but there was no effect on the c-Fos expression in the NA.The third part, after intraperitoneal injection of hexamethonium, we observed the changes of gastric acid secretion and gastric mucosal injury degree which were induced by the RWIS. The method of pylorus ligation was used to collect gastric juice. The gastric juice volume was significantly reduced and the output of H+ were significantly decreased in the injection of hexamethonium group. The gastric ulcer caused by the RWIS was significantly reduced.Conclusion: These results indicate that lesioning VMH could increase the gastric acid secretion and c-Fos expression in the brain stem during the RWIS.