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

Quantification of neural and hormonal receptors at the prostate of long-term sexual behaving male rats after lesion of pelvic and hypogastric nerves

Prostate function is regulated by androgens and a neural control via the pelvic and hypogastric nerves. As such, this sexual gland contains receptors for acetylcholine and noradrenaline, although it is unknown whether the expression of these receptors is affected by sexual behavior and even less by denervation of the gland. Thus, the purpose of this work was to evaluate the effect of repeated sexual behavior on the expression of noradrenaline, acetylcholine, and androgen receptors at the prostate, and how they are affected by denervation. To achieve this, we used sexually experienced males denervated at the pelvic or hypogastric nerves, or both. The messenger (mRNA) and protein for androgen, noradrenergic, and cholinergic receptors were evaluated. The weight of the gland and the levels of serum testosterone were also measured. We found that: (1) sexual behavior was not affected by denervation; (2) blood testosterone levels increased due to sexual behavior but such increase is prevented by denervation; (3) the weight of the ventral prostate increased with sexual behavior but was not affected by denervation; (4) AR messenger levels increased with sexual behavior but were not altered by denervation; (5) the messenger for noradrenergic and cholinergic receptors decreased after denervation, and those for muscarinic receptors increased, and (6) only AR protein decreased after denervation of both nerves, while those for other receptors remained unchanged. In summary, we show that the three receptors have different regulatory mechanisms, and that only androgen receptors are regulated by both autonomic systems.

Type 1 deiodinase activity and generation of triiodothyronine (T3) in prostate of sexually active rats

BACKGROUND

Thyroxine (T(4)) and triiodothyronine (T(3)) are involved in the development and function of the male reproductive system. The type 1 deiodinase enzyme (D1) plays a major role in the intracellular conversion of T(4) to the active form, T(3). D1 is expressed in the prostate of pubescent rats, but it is unknown whether locally generated T(3) is involved in the development and function of this gland.

METHODS

D1 activity was analyzed in prostates from neonatal to old rats. Local T3 generation (D1 and T3 levels) was evaluated in adult animals with 1-5 months of continuous sexual activity. D1 activity was measured by the radiolabeled-iodide-release method and T(3) concentration by radioimmunoassay. Secretory activity of the prostate was evaluated by a morphological analysis of epithelium (hematoxilin-eosin stain) and by measuring the activity of acid phosphatase as a marker enzyme for secretion.

RESULTS

The highest prostate D1 activity was expressed around puberty, and it was almost undetectable during the neonatal period and with aging. Interestingly, 1 and 4 months of sexual activity avoided the decrease of D1 activity associated with aging. Sexual activity provoked a hypertrophy and functional hyperplasia in all lobes, but D1 and acid phosphatase activity increased only in the ventral lobe. D1 activity correlated with an increase in the prostatic T(3) concentration.

CONCLUSIONS

The increased local generation of T(3) in prostate might be related to: (1) the differentiation/maturation that occurs at puberty and (2) the energy expenditure associated with maintaining the secretory activity of the glandular epithelium.