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Background/Aims Several studies have assessed the effect of cool temperature on colonic peristalsis. Transient receptor potential melastatin 8 (TRPM8) is a temperature-sensitive ion channel activated by mild cooling expressed in the colon. We examined the antispasmodic effect of cool temperature on colonic peristalsis in a prospective, randomized, single-blind trial and based on the video imaging and intraluminal pressure of the proximal colon in rats and TRPM8-deficient mice. Methods In the clinical trial, we randomly assigned a total of 94 patients scheduled to undergo colonoscopy to 2 groups: the mildly cool water (n = 47) and control (n = 47) groups. We used 20 mL of 15°C water for the mildly cool water. The primary outcome was the proportion of subjects with improved peristalsis after treatment. In the rodent proximal colon, we evaluated the intraluminal pressure and performed video imaging of the rodent proximal colon with cool water administration into the colonic lumen. Clinical trial registry website (Trial No. UMIN-CTR; UMIN000030725). Results In the randomized controlled trial, after treatment, the proportion of subjects with no peristalsis with cool water was significantly higher than that in the placebo group (44.7% vs 23.4%; P < 0.05). In the rodent colon model, cool temperature water was associated with a significant decrease in colonic peristalsis through its suppression of the ratio of peak frequency ( P < 0.05). Cool temperaturetreated TRPM8-deficient mice did not show a reduction in colonic peristalsis compared with wild-type mice. Conclusion For the first time, this study demonstrates that cool temperature-dependent suppression of colonic peristalsis may be associated with TRPM8 activation. [ABSTRACT FROM AUTHOR]

Although viral RNA or infectious virions have been detected in the feces of individuals infected with human influenza A and B viruses (IAV/IBV), the mechanism of viral survival in the gastrointestinal tract remains unclear. We developed a model that attempts to recapitulate the conditions encountered by a swallowed virus. While IAV/IBV are vulnerable to simulated digestive juices (gastric acid and bile/pancreatic juice), highly viscous mucus protects viral RNA and virions, allowing the virus to retain its infectivity. Our results suggest that virions and RNA present in swallowed mucus are not inactivated or degraded by the gastrointestinal environment, allowing their detection in feces. [ABSTRACT FROM AUTHOR]