Objective: To investigate the effect of Jianpi Huashi granule on tyrosine hydroxylase

Monoamine oxidase and serotonin transporter expression in brain of rats with diarrhea-predominant irritable bowel syndrome (D-IBS)

and explore its mechanism. Method: SD rats were randomly divided into normal group

model group

Jianpi Huashi granule low

middle and high dose groups (6.25

12.5

25 g·kg-1)

and positive drug group (pinaverium bromide

0.03 g·kg-1)

n=10 in each group. Except the rats in normal group

all the other rats received intragastric administration of Sennae combined with restraint stress to establish D-IBS models. The changes of sucrose preference in different groups were observed at different time points

and Jianpi Huashi granule was used for 14 days. Then immunohistochemical method and Western blot were used to detect the expression levels of tyrosine hydroxylase

monoamine oxidase and serotonin transporter in brain. Result: In the D-IBS model group

the sucrose preference was decreased significantly

the expression of tyrosine hydroxylase in brain was significantly increased

and the expression levels of monoamine oxidase and serotonin transporter in brain were decreased significantly as compared with the normal control group (P<0.01). After treatment

the sucrose preference was significantly increased in medium-and high-dose Jianpi Huashi granule groups and positive drug group (P<0.05

P<0.01) ; except the relative expression of monoamine oxidase in positive drug group

the expression levels of tyrosine hydroxylase in all other treatment groups were decreased significantly and the expression levels of monoamine oxidase and serotonin transporter were increased significantly as compared with the model group (P<0.05

P<0.01). As compared with the positive drug group

the sucrose preference was increased significantly (P<0.05

P<0.01); the expression of tyrosine hydroxylase was decreased significantly (P<0.05

P<0.01); the expression of monoamine oxidase in middle and high-dose Jianpi Huashi granule groups and the positive expression of serotonin transporter in high-dose Jianpi Huashi granule group were increased significantly (P<0.05

P<0.01); the expression levels of monoamine oxidase and serotonin transporter were increased significantly in low

middle and high dose Jianpi Huashi granule groups (P<0.05

P<0.01). Conclusion: Jianpi Huashi granule reduced the content of serotonin transporter in brain of rats with D-IBS

which was closely related to down-regulating the expression of tyrosine hydroxylase and up-regulating monoamine oxidase and serotonin transporter in brain. This may be one of the therapeutic mechanisms of Jianpi Huashi granule for D-IBS.