Effects of electroacupuncture at ST25 and BL25 in a Sennae-induced rat model of diarrhoea-predominant irritable bowel syndrome

Background Electroacupuncture (EA) may have a role in the treatment of diarrhoea symptoms. Serotonin (5-hydroxytryptamine, 5-HT) is an important neurotransmitter and paracrine signalling molecule in the gastrointestinal (GI) tract, which initiates peristaltic, secretory, vasodilatory, vagal and nociceptive reflexes. In addition, according to the results of our previous report, EA stimulation mediates GI peristalsis by increasing expression of 5-HT and tryptophan hydroxylase (TPH). Aim To investigate the effect of EA at acupuncture points ST25 and BL25 in a rat model of diarrhoea. Methods A diarrhoea-predominant irritable bowel syndrome (IBS-D) model was induced by Folium Sennae in 24 rats, which remained untreated (n=6) or received EA at ST25 (n=6), BL25 (n=6) or the combination of ST25 and BL25 (n=6). A control group of healthy rats was also included (n=6). After treatment, changes in loose stool and small intestine transit rates, enterochromaffin (EC) cell number, expression of TPH, and faecal/colonic 5-HT contents were measured. Results Loose stool and small intestine transit rates, EC cell numbers, colonic TPH expression and faecal/colonic 5-HT content of IBS-D rats were significantly increased relative to controls (p<0.05) and all these parameters were improved by EA at ST25, BL25, or ST25 and BL25 in combination (all p<0.05 vs untreated IBS-D rats). Conclusions EA at ST25 and/or BL25 had a positive effect on objective markers of diarrhoea in a IBS-D rat model and induced changes in EC cell number, colonic TPH and 5-HT contents. The effects of EA stimulation at ST25/BL25 on IBS-D rats may be mediated by excitation of sympathetic nerves.