effect of circadian rhythm on antiulcer activity of hydroxyzine in cold stress induced ulcer in wistar albino rats

circadian rhythms are driven by endogenous clock gene and affects in several gastric parameters causing ulcerogenesis. the study was aimed to evaluate the time dependent antiulcer activity of hydroxyzine in cold-stress-induced ulcer model. the ulcer protection effect of hydroxyzine was studied at various time intervals (9 am, 1 pm, 5 pm, 91 pm, 1 am and 5 am) in cold stress ulcer model using wistar albino rats. comparison of hydroxyzine and control group showed significant ( p <0.05) decrease in gastric acidity at 9 pm. the free acidity was reduced significantly ( p <0.001) at 5 am within 24 h time. no significant change was observed in free acidity in control and hydroxyzine-treated animals. the total acidity was significantly ( p <0.001) reduced in hydroxyzine group at 5 am within 24 h time. comparison between hydroxyzine and control group at 1 am showed significant ( p <0.01) reduction in total acidity in hydroxyzine treated animals. ulcer index was found to be significantly low ( p <0.001) in hydroxyzine-treated animals at 5 am within 24 h. the ulcer index of hydroxyzine-treated animals was significantly ( p <0.001) reduced at 9 am as compared with control group of 9 am. lipid peroxidation was significantly ( p <0.01) reduced in hydroxyzine-treated animals at 5 am within 24 h time. mucin was significantly ( p <0.001) increased in hydroxyzine-treated animals at 1 am within 24-h time. the mucin content was significantly ( p <0.001) rose in hydroxyzine group at 5 am when compared to control at 5 am. the study reveals the role of biological clock on antiulcer activity of hydroxyzine.