Objective:To investigate the distribution of serotonin 5-HT2A and 5-HT7 receptors in different motoneuron populations in spinal Onuf’s nucleus of male rats

and their relationship with the central modulation of the urogenital functions.Methods:Ten adult SD rats(eight male rats and two female rats)were randomly divided into gender control group(n=4

include two male and two female rats)and retrograde tracing group(male rats

n=6).In gender control group

after the spinal L5~6 segments were removed and cut

sections were treated with 5-HT2A or 5-HT7 receptors immunohistochemical stain.In retrograde tracing group

recombinant pseudorabies virus(PRV-152 )were injected into right ischiocavernosus muscles(IC group;n=3)or right external urethral sphincter(EUS group;n=3)

respectively.Four days after injection

the L5~6 segments were removed

cut

and treated with 5-HT2A or 5-HT7 receptors double-labeling immunofluorescence stain.Sections were observed by light microscopy or the laser confocal microscopy to detect the distribution of 5-HT2A、5-HT7 receptors in Onuf’s nucleus.Results:5-HT2A receptors immunoreactivity mainly located in the medial part of the dorsolateral nucleus(DLN)of Onuf’s nucleus

and 5-HT7 receptors mainly located in the lateral part of the DLN;5-HT2A and 5-HT7 receptors expression of male rats in Onuf’s nucleus were more dense than female rats.Immunofluorescence double-labeling detection exhibited that 5-HT2A receptors mainly distributed in surrounding motoneurons innervating the IC muscles

and 5-HT7 receptors mainly expressed in neurons innervating the EUS.Conclusion:5-HT2A and 5-HT7 receptors are heterogeneously distributed in different motoneurons of Onuf’s nucleus innervating different striated muscles.5-HT2A receptor might be preferentially involved in regulation of the sexual reflex

and the 5-HT7 receptor may be mainly participated in the micturition reflex.