Effects of Electroacupuncture on the Daily Rhythmicity of Intestinal Movement and Circadian Rhythmicity of Colonic Per2 Expression in Rats with Spinal Cord Injury

Background. Spinal cord injury (SCI) leads to bowel dysfunction. Electroacupuncture (EA) may improve bowel function. Objective. To assess EA on daily rhythmicity of intestinal movement and circadian rhythmicity of colonic Per2 expression in rats with SCI. Methods. Rats were randomized to the sham, SCI, and SCI+EA groups. EA was performed at bilateral Zusanli point (ST36) during daytime (11:00-11:30) for 14 days following SCI. Intestinal transit and daily rhythmicity of intestinal movement were assessed. Circadian rhythmicity of colonic Per2 expression was assessed by real-time RT-PCR. Results. EA shortened the stool efflux time and increased the dry fecal weight within 24 h in SCI rats. Daily rhythmicity of intestinal movements was unaffected by SCI. The expression of colonic Per2 peaked at 20:00 and the nadir was observed at 8:00 in the SCI and sham groups. In the SCI+EA group, colonic Per2 expression peaked at 12:00 and 20:00, and the nadir was observed at 8:00. Conclusion. SCI did not change the circadian rhythmicity of colonic Per2 expression in rats, and daily intestinal movement rhythmicity was retained. EA changed the daily rhythmicity of intestinal movement and the circadian rhythmicity of colonic Per2 expression in rats with SCI, increasing Per2 expression shortly after EA treatment.