Effect of Delayed Estrogen Replacement on Clitoral Corpus Cavernosal Blood Flow and Histologic Composition in Rabbit

Park, Kwangsung; Kim, Min Kyung; Kim, Kang Won; Ahn, Kyu Youn; Lee, Song Eun; Ryu, Soo Bang

Abstract

PURPOSE: A decline in the circulating levels of estrogen impairs clitoral engorgement and leads to histopathological changes in the clitoral corpus cavernosum. The aims of this study were to evaluate the effects of delayed estrogen replacement on the clitoral corpus cavernosal blood flow and histological composition in castrated rabbit.
MATERIALS AND METHODS
New Zealand White female rabbits(3.0-3.5kg) were randomly divided into three groups of five; two groups(castration group, estrogen replacement group) were castrated and the control group underwent sham operations. Nine weeks after surgery, the hormone replacement group received subcutaneous injections of estrogen(50microgram/kg/day), whereas the castrated group received vehicles for 4 weeks. The clitoral blood flow(ml/min/100g tissue) was measured by a laser Doppler flow meter before and after pelvic nerve stimulation(PNS). Clitoral tissue was processed for histology with Masson's trichrome stain. The expression of TGF-beta was examined by immunohistochemistry.
RESULTS
The clitoral corpus cavernosal blood flow after PNS was significantly decreased in the castrated gruop(5.1+/-1.7) compared with the control group(9.3+/-3.1), and increased in the estrogen replacement group(7.4+/-0.4), but without statistical significance compared with the castrated group. On histomorphometry, the percentage of clitoral cavernosal smooth muscle in the castrated group(49.0+/-4.4) was significantly decreased compared with the control(58.7+/-2.3) and the estrogen replacement groups (62.7+/-4.2). The TGF-beta immunoreactivity was increased in both the castrated and estrogen replacement groups.
CONCLUSIONS
Delayed estrogen replacement improved the clitoral corpus cavernosal blood flow and increased the percentage of clitoral cavernosal smooth muscle, even though there was evidence of cavernosal fibrosis in the castrated rabbits. These results suggest that delayed estrogen replacement therapy seems to improve sexual function in menopausal women.