Hesperidin alleviates rat postoperative ileus through anti-inflammation and stimulation of Ca2＋-dependent myosin phosphorylation

Aim： Postoperative ileus （POI） is a postoperative dysmotility disorder of gastrointestinal tract, which remains one of the most perplexing problems in medicine. In the present study we investigated the effects of hesperidin, a major flavonoid in sweet oranges and lemons, on POI in rats. Methods： SD rats were administered hesperidin （5, 20, and 80 mg·k^-1·d^-1, ig） for 3 consecutive days. POI operation （gently manipulating the cecum for 1 min） was performed on d 2. The gastrointestinal motility and isolated intestinal contraction were examined I d after the operation. Then the myosin phosphorylation and inflammatory responses in cecum tissue were assessed. Smooth muscle cells were isolated from rat small intestine for in vitro experiments. Results： The gastric emptying and intestinal transit were significantly decreased in POI rats, which were reversed by administration of hesperidin. In ileum and cecum preparations of POI rats in vitro, hesperidin （2.5-160 μmol/L） dose-dependently increased the spontaneous contraction amplitudes without affecting the contractile frequency, which was blocked by the myosin light chain kinase （MLCK） inhibitor ML-7 or verapamil, but not by TTX. Furthermore, administration of hesperidin increased the phosphorylation of MLC20 in the cecum tissue of POI rats. Moreover, administration of hesperidin reversed the increased levels of inflammatory cytokines, iNOS and COX-2 in cecum tissue of POI rats. In freshly isolated intestinal smooth muscle cells, hesperidin （5-80 μmol/L） dose-dependently increased the intracellular Ca2＋ concentration as well as the phosphorylation of MLC20, which was abrogated by ML-7 or siRNA that knocked down MLCK. Conclusion： Oral administration of hesperidin effectively alleviates rat POI through inhibition of inflammatory responses and stimulation of Ca2＋-dependent MLC phosphorylation.