Objective        To determine the effect of stem cell factor (SCF) on the number of interstitial cells of Cajal (ICCs) and the contraction of detrusor in the rats with underactive bladder.    Methods      A total of 54 SD rats were randomly divided into 3 groups: control group

detrusor underactivity group (DU

inflicted with bladder outlet obstruction)

and DU+SCF group [intra-peritoneal injection of 0.2 μg/(kg·d) SCF]

with 18 animals in each group. After the rats were sacrificed in 2 weeks later

their blood and bladder samples were harvested. The number of ICCs was analyzed by immunohistochemical and immunofluorescent staining. The serum SCF levels were detected by ELISA. The expression levels of c-kit and SCF in the detrusor tissues were detected by RT-PCR and Western blotting. Change of detrusor spontaneous contraction was tested with detrusor strips in vitro.    Results      The number of ICCs was decreased significantly

the serum SCF level was also reduced significantly

so were the expression of c-kit and SCF at mRNA and protein levels

and the contraction of detrusor was decreased significantly in the DU group compared to the control group (all P0.05). However

exogenous SCF resulted in the increase of ICCs number

enhancement of c-kit and SCF expression levels

and significant improvement of the contraction amplitude and frequence of detrusor (all P0.05).   Conclusion       Exogenous SCF improves the number of ICCs and the contraction of detrusor in DU rats.