Some Pre- and Postjunctional Effects of Castration in Rabbit Isolated Corpus Cavernosum and Urethra

Abstract

Pre- and postjunctional effects of castration were investigated in isolated corpus cavernosum (CC) and prostatic and preprostatic urethral preparations obtained from rabbits that had been castrated surgically 14 days before investigation. Preparations obtained from untreated animals were used as controls. Castration did not change the relaxing effects of SIN-1 (NO donor) or papaverine in CC preparations contracted by noradrenaline (NA). Electrical field stimulation of CC preparations contracted by NA or endothelin-1 produced frequency-dependent and tetrodotoxin-sensitive relaxations. As compared with controls, the electrically induced relaxations were increased in preparations from castrated animals. Pretreatment with prazosin increased the electrically induced relaxations in CC from untreated rabbits, but had no effect on preparations from castrated animals. In CC preparations incubated with 3H-NA, castration significantly reduced the electrically evoked release of 3H. L-NOARG, an inhibitor of NO synthase, had no effect on 3H-efflux. In prostatic, but not preprostatic, urethral preparations contracted by NA, the relaxant effects of SIN-1 and vasoactive intestinal polypeptide were significantly smaller following castration. Furthermore, castration significantly reduced electrically evoked relaxations in prostatic urethral preparations contracted by NA, while in preprostatic urethra, no such effect was seen. Castration or L-NOARG had no effect on the electrically induced release of 3H-NA in either of the urethral tissues. The results suggest that the hormonal changes caused by castration may modulate the functional effects in vitro of some parts of the urogenital tract. In penile erectile tissue, the relaxations induced by electrical field stimulation are increased, probably for the most part through a decrease in the neuronal release of NA. In prostatic urethra, on the other hand, electrically evoked relaxations are decreased, possibly as a result of an impaired ability of the smooth muscle itself to respond to relaxant agents. In preprostatic urethra, castration has no obvious functional effects. The physiological consequences of these findings in the in vivo situation remain to be established.

Bisphenol A inhibits penile erection via alteration of histology in the rabbit

“…11,12 Holmquist et al reported that castration increase the relaxation of corpus cavernosum strips to electrical stimulation through decrease in the neuronal release of NA. 13 Meanwhile, Baba reported that tissue strips from intact rabbits showed a greater degree of contraction than those of castrated animals, suggesting changes in the adrenergic pathway in response to androgen deprivation. 14 Castration reduces NANC fibers in rat model; 15 however, these fibers are thought to be decreased in the castrated model, 13 suggesting differences in the response to androgens among species.…”

“…13 Meanwhile, Baba reported that tissue strips from intact rabbits showed a greater degree of contraction than those of castrated animals, suggesting changes in the adrenergic pathway in response to androgen deprivation. 14 Castration reduces NANC fibers in rat model; 15 however, these fibers are thought to be decreased in the castrated model, 13 suggesting differences in the response to androgens among species. Recently, Traish et al reported that castration reduces intracavernosal pressure and expression of a1-adrenergic receptor while increasing phosphodiesterase type 5 activity.…”

Association of lower urinary tract symptoms and erectile dysfunction: pathophysiological aspects and implications for clinical management

“…53 Upon castration, electrically evoked relaxations of the smooth muscle of the prostatic urethra were decreased and this effect was ascribed to an impaired ability of the smooth muscle to respond to relaxant agents. 54 The effects of testosterone can be partially explained by the fact that NO production is androgen dependent in the urinary tract. NOS in an earlier study had appeared to be androgen dependent in the urogenital tract of the rat.…”

Smooth muscle pathology and erectile dysfunction

“…31,32 In rabbits, with strips of cavernosal tissue precontracted with a-adrenergic agonists, electrical field stimulation caused a greater degree of relaxation in strips from castrate than from intact animals. 33 The contraction in response to norepinephrine may also be hormonally dependent, with strips from intact rabbits showing a greater degree of contraction than tissues from castrates in response to the same concentration of the agonist. 34 Relaxation in response to field stimulation was greater in castrated than in intact animals, although relaxation in response to NO donor drugs was not different in the two groups, suggesting that basal NOS may be adequate to mediate the erectile response.…”