Effects of moxibustion on behaviors and tryptophan metabolism-related products in mice with irritable bowel syndrome

Abstract

ObjectiveTo observe the effect of moxibustion on behaviors and related products of tryptophan (Trp) metabolism in the colon of mice with irritable bowel syndrome (IBS), and to explore the mechanism of moxibustion in the IBS treatment.MethodsTwenty-four mice were randomly divided into a normal group, a model group, a moxibustion group, and a probiotic group, with 6 mice in each group. The visceral pain model of IBS was established by enema with 2,4,6-trinitrobenzene sulfonic acid (TNBS) solution. Mice in the moxibustion group were treated with mild moxibustion at bilateral Zusanli (ST36), and those in the probiotic group were treated with probiotics such as Bifidobacterium by gavage. Abdominal withdrawal reflex (AWR) test, elevated plus-maze (EPM) test, and forced swimming test (FST) were performed after treatment. The expression levels of 5-hydroxytryptamine (5-HT) and tryptophan hydroxylase 1 (TPH1) in the colon were detected by immunofluorescence, and the expression levels of Trp, kynurenine (Kyn), and indole-2,3-oxygenase (IDO) in the colon were detected by enzyme-linked immunosorbent assay.ResultsCompared with the normal group, the AWR scores were increased significantly in the model group under different pressure values (P<0.01), the open-arm staying time and open-arm entries in the EPM test were decreased significantly (P<0.01, P<0.05), the motionless time in the FST was increased significantly (P<0.01), and the expression levels of colonic Trp, TPH1, IDO, 5-HT, and Kyn were increased significantly (P<0.01) in the models. Compared with the model group, the AWR scores were differently decreased (P<0.05 or P<0.01), the open-arm entries in the EPM test were increased (P<0.05), the motionless times in the FST were decreased (P<0.05), and the colonic expression levels of Trp, TPH1, IDO, and 5-HT were decreased (P<0.01 or P<0.05) in the moxibustion and probiotic groups; the open-arm staying time was significantly increased in the moxibustion group (P<0.01), and the colonic expression level of Kyn was significantly decreased in the probiotic group (P<0.01).ConclusionMoxibustion at Zusanli (ST36) improves visceral pain and pain mood and down-regulates the expression levels of colonic TPH1, IDO, Trp, 5-HT, and Kyn in IBS mice.