Objective: To explore the effect of Xiaofu Tongjie Fang (XFTJF) on expressions of vasoactive intestinal peptide (VIP) and aquaporin 3 (AQP3) in colon tissue of rats with functional constipation. Method: Fifty adult male SD rats were randomly divided into the control group

the model group

the high-

medium-and low-dose XFTJF groups (380

190

95 g·kg-1) of 10 rats in each group. The functional constipation model was induced by using compound diphenoxylate tablets (5 mg·kg-1) orally. The rats received intragastric administration of XFTJF for 3 weeks. The general performance

the time to first black stool and fecal water content were observed. The expressions of VIP and AQP3 in rat colon tissue were detected by using immunohistochemical method. The mRNA expression levels of VIP and AQP3 in colon tissue were further detected by using RT-qPCR. Result: Compared with the control group

the time to first black stool significantly prolonged

fecal water content reduced

VIP mRNA level decreased

and AQP3 mRNA level increased in the model group (P <0.05

P <0.01). Compared with the model group

the time to first black stool shortened

fecal water content increased

VIP mRNA level increased

and AQP3 mRNA level decreased in all XFTJF groups (P <0.05

P <0.01). Conclusion: The occurrence of functional constipation in rats is probably related to the abnormal expressions of VIP and AQP3 in colon tissue. The mechanism of XFTJF in the treatment of functional constipation may be realized through regulating the expressions of VIP and AQP3 in colonic tissue.