P011 The effect of melatonin treatment on DSS induced colitis and probable mechanism by microarray

Abstract

Background: There are complex and various causes in the pathogenesis of inflammatory bowel disease. Stressful condition has reported aggravation or reactivation of inflammatory bowel disease. Thus, we tried to investigate the effect of stress caused by sleep deprivation (SD) on DSS induced colitis model. Also, we designed to evaluate the mechanism of melatonin on such condition by gene expression after melatonin treatment. Methods: We used the 5 groups of C57BL/6 mice. Group I: control, Group II: 2% DSS induced colitis for 7days, Group III: 2% DSS induced colitis and melatonin treatment, Group IV: 2% DSS induced colitis with sleep deprivation (SD, 20hr/d) and Group V: 2% DSS induced colitis with SD and melatonin treatment. Specially designed modified multiple platform water baths for sleep deprivation were used. Melatonin (10mg/kg) or saline was injected daily by intraperitoneal route. The mice were sacrificed after finishing administration of melatonin or saline for 4 days. We checked body weight and stool color daily. Degree of colitis was evaluated after H&E stain. Also proinflammatory cytokines from serum were checked using Bio-Plex Pro Mouse Cytokine assay kit (Bio-Rad, Hercules, CA, USA). RNA was isolated from the colon of mice in each group and collected to analyze by microarray and ontology. We confirmed significant changes of expression of important genes by RT-PCR and immunohistochemical staining. Results: Sleep deprivation worsens body weight reduction of mice and exacerbate the severity of colonic inflammation. Administration of melatonin reduced the rate of weight loss and severity of mucosa injury compared with saline injection group. Increased expression of pro-inflammatory cytokines such as IL-6, TNF-alpha, IFN-gamma was significantly reduced with melatonin supplementation. About 68 genes were significantly changed by 2% DSS, sleep deprivation and melatonin in microarray. In real time PCR there are significant change of adipoq and Aqp8 gene, which are related with adiponectin and aqaoporin-8 protein. Conclusions: Sleep deprivation acts as an aggravating factor, whereas melatonin acts as an improving factor of inflammation. This study shows melatonin affects both inflammation and sleep control. Especially genetic microarray study revealed that melatonin may regulate inflammation by modulating adiponectin and aquaporin pathway in DSS induced colitis.