| Ventromedial hypothalamic nucleus (ventromedial hypothalamic nucleus, VMH), as the largest nuclei at the base of hypothalamus, has been well studied because of its clear boundary. Large numbers of researchers have indicated that the most important function of VMH, known as "satiety center", was to control the feeding of mammalian. Previous studies suggested that, VMH is involved in the regulation of gastric motility. Li and Su reported that the frequency of gastric motility and intragastric pressure were significantly reduced when VMH was treated with unilateral electrical stimulation, while the gastric motility was increased after unilateral electrolytic lesion. J.P.Duggan and D.A.Booth's studies revealed that gastric emptying rate was accelerated within a few hours after VMH lesions, and this phenomenon was still observed after 1 week. R.M.Black et al recorded that gastric emptying is significantly accelerated in day 9 to day 16 after VMH lesion, and ad libitum VMH-lesioned rats demonstrated faster than restricted VMH-lesiond and control rats in rates of gastric emptying. Our laboratory studies observed hyperactivity of the gastric motility, an increase in gastric acid secretion and acute gastric mucosal injury during restraint water-immersion stress, and found that gastric motor hyperactivity was an important reason of gastric mucosal injury. However, under restraint water-immersion stress ,the effect of VMH on gastric motility and gastric ulc er was unclear. Zhang found that restraint water-immersion stress increases expression of c-Fos protein in VMH, PVN and SON ,indicating that VMH, PVN and SON are involved in the process of restraint water-immersion stress. However, the relationship among VMH, PVN and SON was still unknown. Therefore, this present study was designed to examine the effect of VMH lesions on gastric motility,gastic ulcer and c-Fos expression in PVN, SON.To further explore the role of VMH in gastric ulcer induced by restraint water-immersion stress.This study was divided into two parts:The first part recorded gastric motility and gastric mucosal injury after bilateral VMH lesions. The experiment was divided into two groups: one group of rats were treated with restraint water-immersion stress and recorded the gastric motility 5 days after bilateral VMH lesions. The results showed that, compared to the control group ,there was no significant difference on frequency, amplitude, duration, time-percentage of gastric motility and gastric motility index . Another group of rats were treated with restraint water-immersion stress and recorded the gastric motility 15 day after bilateral VMH lesions. The results showed that, compared with the control group, the frequency, duration, time-percentage of gastric motility in lesion group was not significantly different. However, significant differences were detected among the amplitude, gastric motility index. The amplitude and gastric motility index were significantly larger than the control group. Aggravated gastric mucosal injury was also founded in 15 days lesion group.The second part observed SON and PVN c-Fos expression in restraint water-immersion stress after bilateral VMH lesions. The results showed that compared with the control group, c-Fos expression of SON and PVN was significantly enhanced. This indicated that VMH had an inhibition effect on the PVN and SON during restraint water-immersion stress.
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