OBJECTIVETo explore the mechanism and efficiency of Changji'an (CJA) in treating irritable bowel syndrome through studying the relationship between serotonin transporter (SERT) and visceral hypersensitivity in rats.

METHODSMale SD rats were randomly divided into 4 groups: the normal control group, the model group, the high-dosage and low-dosage CJA (CJAH and CJAL) groups. Visceral hypersensitivity model was established by colorectal distension. Normal saline and different doses of CJA were administrated to rats respectively, starting from the 10th day of modeling for 10 days. After then, the abdominal withdrawal reflex (AWR) was scored for semi-quantitative estimation of visceral sensitivity, and tissues of brain and colon were harvested for detecting expressions of SERT and serotonin (5-HT) with Western blot, real-time PCR and immunohistochemistry.

RESULTSAs compared with the normal controls, in model rats, the AWR score and content of 5-HT in intestinal mucosa were higher (P < 0.05), protein and mRNA expressions of SERT in colon and nucleus raphes dorsalis (NRD) were lower (P < 0.05), but all these indexes were improved significantly after CJA treatment, either in the CJAH or CJAL group (all P < 0.05). Besides, the number of 5-HT energic neuron in the model group and CJA groups was lower than that in the normal control group (P < 0.05).

CONCLUSIONCJA has therapeutic effect for improving visceral hypersensitivity in irritable bowel syndrome by way of regulating colonic expression of SERT and content of 5-HT.