Changrun Formula Relieves Functional Constipation by Improving Intestinal Motility in Rats

<b>Background and Study Aim:</b> Changrun Formula (CRF) is a representative traditional Chinese medicine prescription for functional constipation (FC). However, the mechanism by which CRF alleviates FC remains unclear. Therefore, this study aimed to investigate the therapeutic mechanism of CRF in an FC rat model. <b>Material and Methods:</b> A total of 72 healthy SD rats were selected and randomly divided into six groups: the blank group, model group, hemp seed pill (HSP) group, high-dose CRF group, medium-dose CRF group, and low-dose CRF group. Except for the blank group, all the other groups were administered compound diphenoxylate via oral gavage to establish the FC rat model with impaired intestinal motility. The expression of genes related to intestinal motility in the colon tissues of rats was analyzed using Western blotting and real-time PCR. The effect of CRF on isolated colonic smooth muscle was assessed through electrophysiological analysis. <b>Results:</b> Compared with the blank group, the other groups exhibited a longer time to expel the first black stool and a reduced number of fecal particles within 6 h, confirming the successful establishment of the FC rat model. Furthermore, the expressions of HCN1, c-kit, and SP in the colon tissue of the model group were significantly decreased, while the expression level of VIP was significantly increased. HCN1 was found to colocalize with c-kit, SP, and VIP. Treatment of CRF (high and medium doses) significantly increased the expressions of c-kit, SCF, HCN1, and HCN2, enhanced the contractile movement of colonic smooth muscle, and improved muscle tension. <b>Conclusions:</b> CRF likely improves intestinal motility by targeting HCN1 and HCN2 ion channels and the SCF/c-kit signaling pathway, thereby alleviating FC symptoms in rats.