Duodenal acidification stimulates gastric H2S release through upregulating mRNA expression of cystathionine gamma lyase

Introduction: It has been reported the alkaline response of pancreas to duodenal acidification is partly mediated through duodenal release of H2S, but till now the effect of duodenal acidification on gastric H2S release has not been investigated. Therefore, the present study designed to evaluate the effects of duodenal acidification on gastric H2S release and level of mRNA expression of cystathionine gamma lyase (CSE). Methods: Twenty four rats were randomly assigned into 3 groups (8 in each). They were control, pH2-, and pH3-treated groups. Under anesthesia, animals underwent midline laparotomy. Neutral isotonic saline or acidic isotonic solutions (pH=2 or 3) were injected in the duodenum 1 cm just below the pyloric sphincter. Ninety minutes after beginning the experiment, animals were sacrificed, stomachs ligated at lower esophageal sphincter and 2 ml saline infused in the stomach through pylorus and then gastric content was drained for measuring the pH. Two samples of gastric mucosal tissue were quickly snap-frozen and stored in liquid nitrogen for measuring the mucosal H2S concentration using ELISA kit and quantifying the mRNA expression of CSE by quantitative real-time PCR. Results: Duodenal acidification with acidic solution (pH=2) increased the gastric release of H2S and upregulated mRNA expression of CSE in gastric mucosa. The gastric mucous content was significantly increased in response to duodenal application of acidic solutions with pH2 and 3. Conclusion: Our findings indicated the stimulatory effect of duodenal acidification on gastric H2S release and mucous content is mediated through upregulation of CSE mRNA expression.