Colonic myoelectric activity of rats with slow transit constipation and its pathogenesis

    LIU Haiª²Feng1, HE Junª²Tang2, WANG Xingª²Wei2, JIANG Liª²Guo1

    1Department of Gastroenterology, General Hospital, Chinese People¬ðs Armed Police Forces, Beijing 100039, China, 2Department of Gastroenterology, Southwest Hospital, Third Military Medical University, Chongqing 400038, China

    ¡¾Abstract¡¿ AIM: To study the changes of colonic myoelectric activity of rats with slow transit constipation and to explore the pathogenesis by investigating the changes of VIP and SP nerves. METHODS: Thirtyª²two healthy Wistar rats were randomly divided into control group and model group with slow transit constipation. After 120 d, the colonic myoelectric activity was recorded and the time of colonic transit was measured. The VIP nerves and SP nerves were studied in colonic myenteric plexuses of the rats with histochemistry and immunohistochemistry. RESULTS: In some model rats, the frequency of colonic slow wave decreased [(5.55¡À1.20) beat/min vs (13.20¡À1.09) beat/min, P<0.01] and the amplitude increased [(0.43¡À0.05) mV vs (0.19¡À0.02) mV, P<0.01] compared with those in the normal rats, and the slow wave form was irregular. In other model rats, the frequency of colonic slow wave increased [(30.85¡À3.86) beat/min vs (13.20¡À1.09) beat/min, P<0.01] and the amplitude was variable [(0.21¡À0.03) mV vs (0.19¡À0.02) mV, P<0.01] and the slow wave form was also irregular. In the colonic myenteric plexuses of rats with slow transit constipation, the VIP immunoreactive positive nerves and cells were significantly lessened (with surface density 19.35¡À1.13) than that in the control group (23.08¡À1.82, P©‚0.01). The SP immunoreactive positive ganglions and fascicles were significantly larger and SP immunoreactive positive cells increased (with surface density 18.14¡À1.18) compared with that in normal rats (15.45¡À1.05, P<0.01). CONCLUSION: Abnormality of colonic myoelectric activity may be one of the mechanisms of slow transit constipation. Dysfunction of colonic transition is associated with the pathological changes of VIP and SP nerves. ......