[Effect of application of herbal medicine paste to "Tianshu" (ST25)on intestinal mobility and expression of vasoactive intestinal peptide and substance P in colonic myenteric plexus in rats with functional constipation].

Objective: To observe the effect of acupoint application at bilateral "Tianshu" (ST25) on intestinal mobility and immunoactivity of vasoactive intestinal peptide (VIP) and substance P (SP) in colonic myenteric plexus of rats with functional constipation (FC), so as to analyze its mechanisms underlying improving FC.

Methods: Forty male SD rats were randomly divided into 4 groups, namely normal control, model, acupoint application and medication, with 10 rats in each group. The FC model was established by gavage of Loperamide Hydrochloride suspension fluid (0.5 mg/mL, 3 mg·kg·d) for 7 days. Herbal medicine paste (composed of Rheum Officinale, Sodium Sulfate, Mangnolia Officinalis, etc.) was applied to bilateral ST25 for 6 h, once daily for 4 weeks. Rats of the medication group were treated by gavage of Mosapride suspension fluid (0.15 mg/mL, 1.58 mg·kg·d) for 4 weeks. After the treatment, the rats were deprived of water for 12 hours, and then treated by gavage of 2 mL of activated carbon suspension, followed by recording the first black defecation time and the number of fecal particles and water content of feces within 6 h so as to assess the intestinal mobility. The immunoactivity and average surface density of VIP and SP positive granules in the colonic myenteric plexus were detected by immunohistochemistry.

Results: Compared with the normal control group, the first black defecation time was significantly prolonged, and the number and water content of fecal particles within 6 h, and the expression and the average surface density of VIP and SP were significantly reduced in the model group (0.01). After the treatment and compared with the model group, the first black defecation time was shortened, and the fecal water content and fecal particle number within 6 h, as well as the expression and the average surface density of VIP and SP were considerably increased in both acupoint application and medication groups (0.01). There were no significant differences between the acupoint application and medication groups in all the indexes mentioned above after the interventions (0.05).

Conclusion: Acupoint application may improve the intestinal motility in FC rats, which may be asso-ciated with its effects in up-regulating the immunoactivity of VIP and SP in colonic myenteric plexus of the large intestine.