Objective: To investigate the effect of Chaizhu Ningchang Fang(CZNCF)on 5-hydroxytryptamine (5-HT) signal system of irritable bowel syndrome(IBS) model rats. Method: Totally 60 male SD rats were randomly divided into the normal group

the model group

the dicetel group and CZNCF high

medium and low doses (2.5

5

10 g·kg-1) groups. The IBS rat model was established by means of composite stress. After the successful modeling

the rats were orally administered with drugs once a day for one week

and the normal group and the model group were given isovolumetric normal saline

in order to detect the semi-quantitative score in general state

abdominal withdrawal reflex (AWR) score and minimum volume threshold. The 5-HT level in rat serum

tryptophan hydroxylase1 (TPH1)

5-hydroxytryptamine transporter (SERT)

5-hydroxytryptamine 3 receptors (5-HT3R) and 5-hydroxytryptamine 4 receptors (5-HT4R) levels in colon were determined by ELISA. The mRNA expressions of TPH1

SERT

5-HT3R and 5-HT4R were detected by RT-PCR method. Result: Compared with the normal group

the model group showed significant differences in all of semi-quantitative score in general state

AWR score and minimum volume threshold increase (P<0.01) and up-regulation in 5-HT in serum and TPH1

5-HT3R in colon(P<0.05

P<0.01) and decrease in the levels and gene expressions of SERT and 5-HT4R in colon (P<0.05). Compared with the model group

CZNCF significantly decreased the concentrations of the 5-HT in serum

the level of TPH1 in colon

5-HT3R level and gene expression in colon

and up-regulated SERT

5-HT4R level and gene expression in colon (P<0.05). Conclusion: CZNCF may reduce the visceral sensitivity of IBS rats and relieve IBS symptoms by regulating multiple targets of the 5-HT signal pathway of IBS model rats.