OBJECTIVES: To observe the effect of mild moxibustion on stem cell factor (SCF)/tyrosine kinase receptor (c-kit) signaling pathway and visceral hypersensitivity of diarrhea predominant irritable bowel syndrome (IBS-D) model rats with liver-qi stagnation and spleen deficiency syndrome, so as to explore its mechanisms underlying improvement of IBS-D.
METHODS: A total of 24 male Wistar rats were randomly divided into normal, IBS-D model, medication and mild moxibustion groups, with 6 rats in each group. The IBS-D model was established by glacial acetic acid (4%) enema plus restraint stress stimulation once daily for 14 days. Rats of the medication group were treated by gavage of pivamium bromide (15 mg/kg) once a day for 14 days. Mild moxibustion was applied to bilateral "Tianshu"(ST25), "Shangjuxu"(ST37) and "Taichong"(LR3) for 20 min, once daily for 14 consecutive days. After the intervention, the rats' general state of each group were observed. The rate of loose stools (LSR), and the minimum volume threshold for abdominal withdrawal reflex(AWR) were observed, and the open field test was used to assess the state of rats' motor activities (including rearing times, grooming times and total number of square-crossings in 5 min). Morphological changes of the colon tissue were observed by hematoxylin-eosin (H.E.) staining, The count of mast cells (MC) in the colon tissues was determined by toluidine blue staining. Contents of serum 5-hydroxytryptamine (5-HT) and substance P (SP) were determined by enzyme-linked immunosorbent assay (ELISA). The relative expression levels of SCF and c-kit mRNAs and proteins in the colon tissues were detected by real-time quantitative PCR and Western blot, respectively.
RESULTS: Compared with the normal group, the body weight, minimum volume threshold of AWR, total numbers of square-crossing, rearing times and grooming times were significantly decreased (P<0.05), and the LSR, number of MC, contents of 5-HT and SP, and the expression levels of SCF and c-kit mRNAs and proteins were considerably increased in the model group (P<0.01). In comparison with the model group after interventions, the body weight, minimum volume threshold of AWR, total numbers of square-crossing, rearing times and grooming times were apparently increased in both medication and moxibustion groups (P<0.05, P<0.01), and the LSR, number of MC, 5-HT and SP contents in both medication and moxibustion groups, and the expression levels of SCF and c-kit mRNA and protein in the moxibustion group (not in the medication group) were obviously decreased (P<0.05, P<0.01). H.E. staining showed that in the model group, a small amount of inflammatory cells in the mucosal layer of colon tissue could be seen. in the medication group, a small number of lymphocytes in colon tissue were observed, while in the mild moxibustion group, a small amount of neutrophils in colon tissue were observed.
CONCLUSIONS: Mild moxibustion can reduce visceral hypersensitivity and improve abdominal pain, diarrhea and locomotion state in IBS-D rats with liver-qi stagnation and spleen deficiency syndrome, which may be associated with its functions in reducing the number of MC and the levels of 5-HT and SP and down-regulating the activities of SCF/c-kit signaling pathway.