Electroacupuncture regulates colonic motility in a rat model of stress

OBJECTIVE: It is well established that endogenous and exogenous corticotrophin-releasing factor (CRF) stimulates colonic motility in rodents. Electroacupuncture (EA) has shown promise in relieving stress responses and alleviating colonic dysmotility, but less is known about its underlying mechanism of action in this context. This study was designed to elucidate the effects of EA on colorectal dysfunction in a rat model of stress and to clarify the underlying mechanism. METHODS: A rat model of stress was induced using exogenous CRF. Colonic propulsion was evaluated by the bead latency test, and colorectal motility was recorded in vivo by implanting a manometric capsule into the colorectal lumen. To clarify the role of CRF receptors type 1 and 2 on stress-induced colonic dysfunction, corresponding selective antagonists (CP-154526 and Astressin 2B, respectively) were administered accordingly. Western blot analysis was used to detect protein expression of CRF and its receptors in the hypothalamus and colorectum. RESULTS: CRF-induced stress significantly accelerated colonic motility. EA treatment alleviated colonic motor dysfunction and reduced colonic propulsion. CP-154526, but not Astressin 2B, reversed CRF-induced colonic dysmotility, suggesting an essential role of CRF receptor type 1 in stress-induced colonic motor disorders. EA treatment resulted in an inhibition of the protein overexpression of CRF receptor type 1 in both the hypothalamus and colorectum in this rat model of stress. CONCLUSIONS: EA ameliorated stress-induced colonic dysmotility, most likely through regulation of central and peripheral expression of CRF receptor type 1.