Effect of melatonin and vitamin C on gastric ulcer in cholestatic rats

The frequency of gastrointestinal ulceration is higher in cholestatic than in healthy population.Melatonin is powerful antioxidant, that does not undergo redox cycling.Vitamin C is an antioxidant,that undergo redox cycling. Cysteamine is a most potent agent for inducing gastrointestinal ulcer and its ulcerogenic effect may be due to generation of ROS, and increasing duodenal endothelin-1 concentration. The aim of this study was to evaluate the effect of pretreatment with melatonin on cysteamineinduced gastric ulcer in unoperated control (UOC), and bile duct-ligated (BDL) rats. This study have performed on 2 groups of rats: UOC and BDL. each group was divided into 4 subgroups.these subgroups were treated with saline, cysteamine, vitamin C plus cysteamine and melatonin plus cysteamine respectively.All rats were killed 24h after the last injection and stomach was prepared for calculation of j.score. In BDL group, the common bile duct was doubly ligated and after7 days, rats had shown overt jaundice. BDL group was treated like the UOC group . In UOC group, injection of cysteamine was associated with significant increased in j.score compared with saline group. injection of vitamin C and melatonin, was associated with decrease in and j.score compared with cysteamine group. In BDL group injected with cysteamine, j.score were significantly more sever compared with saline group. injection of vitamin C and melatonin was associated with significant decrease in j.score compared with cysteamine group. Our results suggest that pretreatment with melatonin , protect UOC and BDL rats against cysteamine-induced gastric ulcer possibly by ability to improve oxidative stress.