[Effect mechanism of blistering moxibustion on visceral hypersensitivity of irritable bowel syndrome in mice based on 5-HT signal pathway].

OBJECTIVE

To observe the effect of blistering moxibustion on the expression levels of 5-hydroxytyptamine (5-HT) and its receptors of the colon tissue in the mice with visceral hypersensitivity of irritable bowel syndrome (IBS), so as to explore the effect mechanism of blistering moxibustion in treatment of IBS.

METHODS

Forty SPF-grade newborn Kunming mice were randomly divided into a normal group, a model group, an antagonist group and a blistering moxibustion group, 10 mice in each one. Before modeling, the injection with 0.2 mL parachlorophenylalanine (PCPA) was given on the lateral ventricle in the antagonist group. The endorectal glacial acetic acid stimulation combined with tail clipping was used to prepare the model of visceral hypersensitivity of IBS in the model group, the antagonist group and the blistering moxibustion group. After modeling, in the blistering moxibustion group, the intervention with blistering moxibustion was exerted at "Zhongwan" (CV 12), "Tianshu" (ST 25) and "Zusanli" (ST 36), once herbal irritant plaster at each acupoint, for 2 h each time, once a week, consecutively for 3 weeks. Abdominal withdrawal reflex (AWR) score and electromyographic (EMG) amplitude of abdominal muscles were adopted to evaluate the visceral hypersensitivity. HE staining was applied to observe the morphological changes in colon tissue, and immunohistochemistry was to determine the expression levels of 5-HT and its receptors.

RESULTS

Compared with the normal group, EMG amplitude of abdominal muscles was increased under 20, 40 mm Hg (1 mm Hg=0.133 kPa) in the model group (<0.05), AWR scores and EMG amplitude of abdominal muscles under 60, 80 mm Hg were all increased in the model group (<0.05). In comparison with the model group, EMG amplitude of abdominal muscles was reduced under 20 mm Hg in the blistering moxibustion group (<0.05), AWR scores were increased under 40 mm Hg in both the blistering moxibustion group and the antagonist group (<0.05); AWR scores and EMG amplitude of abdominal muscles under 60, 80 mm Hg were all reduced in both the blistering moxibustion group and the antagonist group (<0.05). Compared with the normal group, in the model group, the mucosa was slightly disturbed, while, the moderate inflammatory cells were visible in the submucosa. In comparison with the model group, the inherent glands of mucosa were regular in shape and a small number of inflammatory cells were visible in both the blistering moxibustion group and the antagonist group. In comparison with the normal group, the average positive staining area percentage (APSAP) of 5-HT and 5-HTR of the colon tissue was increased, while, APSAP of 5-HTR was reduced in the model group (<0.05). Compared with the model group, APSAP of 5-HT and 5-HTR was reduced in both the blistering moxibustion group and the antagonist group (<0.05).

CONCLUSION

Blistering moxibustion can relieve the visceral hypersensitivity of the mice with visceral hypersensitive IBS and the underlying mechanism is related to the regulation of the gut-brain axis mediated by 5-HT signaling pathway.