Melatonin treatment modulates intestinal microbiota on DSS colitis

Abstract

Background: Melatonin has strong anti-inflammatory potentials in the GI tract. On our previous study, melatonin reduces various inflammatory cytokines on colon tissues and accelerates recovery from injured mucosa. We aimed to know the effect of melatonin on intestinal microbiota.Methods: We used 3 groups of C57BL/6 mice. Group I: control; Group II: chronic colitis group: 2% DSS for 7 days and followed 2 weeks for recovery and then readministered 2% DSS for 7 days; Group III: chronic colitis with melatonin group: add daily melatonin treatment. Melatonin (10 mg/kg) or saline was injected daily by intraperitoneal route. The mice were sacrificed on 28th day. Stools were collected during last 2 days. Genomic DNA from feces was extracted. After amplification of genomic DNA using barcoded primers targeting the V1 to V3 regions of bacterial 16S rRNA genes, pyrosequencing was performed.Results: Fecal microbial analysis demonstrated that firmicutes to bacteroidetes ratio (F/B ratio) is 0.19 in Group I, 0.38 in Group II, and 0.21 in Group III. Melatonin treatment significantly decreased F/B ratio comparing with DSS colitis group (P = 0.015). The increase in bacteroidetes is mainly due to increased bacteroidaceae and prevotellaceae. The decrease in firmicutes is due to decreased lactobacillaceae and erysipelotrichaceae. On principal coordinates analysis, three groups showed clearly separated each other. A phylogenic tree analysis using MOTHUR showed melatonin treatment group was more close to control group.Conclusion: This study showed that DSS-induced colitis altered structure of intestinal microbiota. Melatonin treatments on DSS colitis modulate intestinal microbiota and change them close to control.