Effect of Androgen Deprivation and Replacement on the Penis and Erectile Function in the Adult Rat

Choi, Young Deuk; Park, Jin Ah; Chung, Woo Sik; Choi, Hyung Ki

Abstract

PURPOSE: Androgen plays an important role during penile development and is essential for libido in the male, but its role in the regulation and maintenance of the erectile response has been controversial. We investigated the effect of castration and androgen replacement on penile erection in the adult rat.
MATERIALS AND METHODS
Adult male Spargue-Dawley rats were divided into three groups: control, castration, and androgen replacement after castration. Androgen (testosterone, DHT) was administrated for 7 days at week 1, 2, 3, and 4 after castration. The intracavernosal pressure was recorded after submitting the rats to cavernous nerve stimulation. The percentages of cells in the penis expressing Ki-67 (proliferative index) and of apoptotic cells, assessed by morphologic analysis (apoptotic index), were analyzed. Nitric oxide synthase (NOS) activity was measured by the arginine-citrulline conversion ratio, and expression of nNOS and eNOS was determined by Western blot analysis. RESULT: After castration, a significant increase was noted in the apoptotic index, with a decrease in the expression of nNOS and eNOS. Replacement of androgen increased the proliferative index and the expression of cavernous nerve stimulation; NOS activity and erectile function were restored with androgen replacement.
CONCLUSIONS
These results suggested that the penile tissue and NOS activity of the adult rat are affected by the androgen milieu and androgen such as testosterone and DHT play a direct role in the erectile function at the level of the erectile tissue.