The effect of sexual activity on androgen metabolism, androgen-receptor translocation, and glandular weight of ventral prostates of rats

Abstract

Abstract. The present study was conducted to determine whether sexual activity exerts an effect on the action of androgen in the rat prostate. Eight-week-old Sprague-Dawley male rats were divided into two groups. Rats were grouped with female rats (sexualactive), or male (sexual-inactive) rats, and sacrificed 6 months later, The ventral prostates were dissected, homogenized and processed into cytosol and nuclei fractions. Testosterone and dihydrotestosterone were quantified by radioimmunoassay, and androgen receptor was determined by 'exchange assay' with radioactive methyltrienolone incubated for 18 h at 15°C. The main result were: 1) The steroid levels of testosterone and dihydrotestosterone in plasma and in the cytosolic fraction of prostate showed no significant difference between the two group of rats. 2) The prostatic nuclear dihydrotestosterone concentration of the sexual-active group (4.3 ± 0.83 pmol/mg DNA, N = 6) was significantly higher (P< 0.01) than that of the sexual-inactive group (1.68 ± 0.43, N = 6). 3) The androgen receptor was significantly higher (P< 0.05) in nuclear extract (0.64 ± 0.11 pmol/mg DNA, N = 6) and significantly lower (P< 0.01) in cytosol (53.4 ± 5.7 fmol/mg protein, N = 6) of the sexual-active group than those of the sexual inactive group (0.42 ± 0.13, N = 6 and 74.6 ± 11.8, N = 6, respectively). 4) In the sexual-active group, prostatic DNA content (3.82 ± 0.52 mg DNA/g tissue, N = 12) and prostatic weight (631 ± 122 mg, N = 29) was significantly greater (P< 0.05 and P< 0.01, respectively) than in the sexual-inactive group (2.82 ± 1.30, N = 15 and 514 ± 132, N = 40). It is suggested that the sexually experienced rats have significantly heavier prostates, which is associated with a higher concentration of dihydrotestosterone and androgen receptor in the nuclei.