Effects Estrogen on the Expression of NOS and Histologic Composition in Rabbit Clitoris

Yoon, Ha Na; Chung, Woo Sik; Park, Young Yo; Shim, Bong Suk; Han, Woon Sup; Kwon, Sung Won

Abstract

PURPOSE: Many investigators suggested that changes in hormonal environment in the postmenopausal women functionally or histologically effect the clitoris and vagina. We investigated the mechanism of female se xual dysfunction occurring in the decreased hormonal status, and aimed to establish and experimental base for the hormone replacement in postmenopausal women to correct sexual dysfunction.
MATERIALS AND METHODS
Twenty mature female New Zealand white rabbits were randomly divided into three groups; control group, oophorectomy group, estrogen replacement group after oophorectomy. Nitric oxide synthase (NOS) activity and the degree of expression of neuronal NOS (nNOS) and endothelial NOS (eNOS), collagen content in clitoral tissues were analysed.
RESULTS
nNOS and eNOS were significantly increased in the oohporectomized group while decreased in the estrogen replacement group (p<0.01). NOS activity showed the similar pattern of change (p<0.05). Oophorectomy induced a significant increase in collagen content, while the ratio of smooth muscle content was increased significantly after the estrogen replacement (p<0.01).
CONCLUSIONS
Estrogen deficiency induces collagen synthesis and decreases the content of smooth muscle in clitoris, resulting in a structural relaxation difficulty. We believe that NOS becomes more active to improve the relaxation difficulty and that hormone replacement helps to restore the normal state of smooth muscle relaxation. Considering these findings, we suggest that estrogen down-regulates NOS and its activity.