Effects of watermelon powder supplementation on colitis in high-fat diet-fed and dextran sodium sulfate-treated rats

The objective of this study was to determine the effects of watermelon on colitis in rats treated with Dextran Sodium Sulfate (DSS) and high-fat diet. We hypothesized that watermelon would reduce colitis severity by maintaining the number of intact crypts and regulating cell homeostasis. Forty rats were divided into four groups: control diet, control diet + DSS,0.33% watermelon powder diet, and 0.33% watermelon powder diet + DSS. After 4 weeks of defined diets, DSS group rats were administered 3% (w/v) DSS (40 kDa) in their drinking water for 2 days. DSS administration increased colonocyte proliferation and apoptosis while decreasing cell differentiation and the number of intact colonic crypts (P < .05). Watermelon treatment reduced the loss of colonic crypts and abolished the effect of DSS on cell proliferation (P < .05). DSS increased mRNA expression of cyclin D1, but this effect was ameliorated by watermelon treatment. These results demonstrate that watermelon supplementation improves colitis by maintaining normal colonic crypt morphology and modulating the homeostasis of cell proliferation and apoptosis.