The Effects of Androgen on Androgen Receptor, Apoptosis and Proliferation in the Penile Erectile Tissue of Adult Rat

Choi, Young Deuk; Choi, Hyung Ki

Abstract

PURPOSE: Androgen plays an important role during penile development and is essential for a normal libido in the male, but its role in the regulation of the androgen receptor and maintenance of erectile response has been controversial. We investigated the effect of androgen on apoptosis, proliferation of the penile erectile tissue and androgen receptor after castration and temporary androgen replacement.
MATERIALS AND METHODS
Male adult Sprague Dawley rats were divided into three groups; sham-operation, castration, and androgen replacement after castration. Androgens (testosterone, DHT) were administrated for 7 days at week 1, 2, 3, and 4 after castration. The weight of whole body and corpus cavernosum and serum testosterone concentration were measured. Androgen receptor expression, percentage of proliferating cells incorporating Ki-67(proliferative index) and percentage of apoptotic cells assessed by morphological analysis(apoptotic index, TUNEL) were analyzed in the penile erectile tissue.
RESULTS
Castration induced a significant decrease in serum testosterone concentration from day 1 and a progressive decrease in the corpus cavernosal weight from day 14. Androgen receptor expression decreased after androgen depletion and was restored with androgen replacement. The proliferative and apoptotic index varied as follows after castration and androgen replacement: a significant increase was noted for apoptotic index with a decrease in the proliferative index and androgen receptor expression after castration. Replacement of testosterone propionate and DHT after castration decreased the apoptotic index with an increase in the proliferative index and the expression rate of androgen receptor.
CONCLUSIONS
The penile erectile tissue of the adult rat was affected by the androgen milieu via the androgen receptor as seen by either cellular apoptosis or proliferation. Therefore, androgens such as testosterone and DHT play a direct role in the erectile function of the rat at the level of the penile erectile tissue.