Effect of cyproterone acetate on puberty in rats

Clinical applications of antiandrogens

Antiandrogens, substances that prevent androgens from expressing their activity at target cells, play an important role in the treatment of prostate cancer. The most frequently used substances have either a steroidal structure (cyproterone acetate) or a non-steroidal structure (Flutamide or Anandron). Antiandrogens have been tested both alone and in combination with treatments aimed at inhibiting testicular secretion (castration, LH-RH analogs), thereby producing complete blockade of androgen secretion and action. Patients treated by such combination protocols have often shown an improvement in the percentage of remissions and, less often, improvement in survival. Administration of antiandrogens improves the clinical symptoms of patients with benign prostatic hypertrophy, but the exact mechanism of their action requires further investigation. Cutaneous manifestations due to hyperandrogenicity (hirsutism, alopecia, acne) have also been improved by cyproterone acetate, which is often given together with estrogens (reversed sequential regime), by spironolactone or topically applied products. Finally, antiandrogens have been successfully used to treat breast cancer in men, early puberty, hypersexuality and sexual deviations.

The effect of androgen deprivation on branching morphogenesis in the mouse prostate

Androgen-induced prostatic development encompasses many individual processes such as ductal branching morphogenesis, cellular proliferation, and secretory cytodifferentiation. Previous studies of ductal morphogenesis (Y. Sugimura, G.R. Cunha, and A.A. Donjacour, 1986, Biol. Reprod. 34, 961-971) demonstrated that the majority (approximately 70%) of ductal tips and branchpoints in the mouse prostate is generated before 15 days of age. Since circulating androgen levels are low during this neonatal period, it is possible that ductal branching morphogenesis may not require the continuous presence of androgens. To test this hypothesis mice were castrated within 24 hr of birth, and prostates from these mice were microdissected at various ages from 5 to 120 days of age to assess the number of ductal tips and branchpoints; wet weight and DNA content were also determined. In intact males wet weight and DNA content increased rapidly between 15 and 60 days of age, after most of the prostatic ductal architecture had been laid down. Neonatal castration considerably reduced the number of tips and branchpoints in both the ventral and dorsolateral prostate, yet both lobes still underwent significant branching morphogenesis in the absence of testes. The administration of anti-androgens to neonatal castrates did not suppress ductal branching to any greater extent than did neonatal castration alone. Androgen replacement immediately following neonatal castration resulted in precocious attainment of the adult number of tips and branchpoints, but caused only modest increases in wet weight. In contrast, when androgen replacement was delayed until adulthood, prostatic wet weight increased to normal adult levels, but the number of ductal tips and branchpoints did not. These experiments show that neonatal prostatic ductal morphogenesis is sensitive to, but does not require, chronic androgen stimulation.

Inhibition of central nervous system aromatase activity: a mechanism for fenarimol-induced infertility in the male rat

Fenarimol (alpha-(2-chlorophenyl)-alpha(4-chlorophenyl)-5-pyrimidine-methanol), a pyrimidine carbinol agricultural fungicide, was previously reported to cause a dose-related decrease in fertility in rats (K. S. Hirsch, E. R. Adams, D. G. Hoffman, J. K. Markham, and N. V. Owen (1986), Toxicol. Appl. Pharmacol. 86, 391-399). Based on the results of a number of reproduction studies (K. S. Hirsch, E. R. Adams, D. G. Hoffman, J. K. Markham, and N. V. Owen (1986), Toxicol. Appl. Pharmacol. 86, 391-399), the infertility appeared to be associated with an impairment of male sexual behavior. When [14C]fenarimol was administered to the dam, high concentrations of radioactivity were observed in the neonatal hypothalamus, which functions in the development and subsequent expression of male sexual behavior. In the present studies fenarimol exhibited neither antiandrogenic nor antiestrogenic activities. The compound did, however, prevent the increase in nuclear estrogen receptors in the brain which normally occurs in the male during the early postnatal period. These results suggested that fenarimol might be acting to inhibit estrogen biosynthesis (via the aromatase enzyme complex) within the central nervous system. [3H]Testosterone was administered to neonatal rats, and the tritiated metabolites were isolated. Testosterone and dihydrotestosterone (17 beta-hydroxy-5 alpha-androstan-3-one) concentrations were similar in all treatment groups. Tritiated estrogens were detected in the brain cell nuclei from control neonates but not in neonates exposed to fenarimol. Fenarimol was also observed to inhibit rat ovarian aromatase activity in vitro. These data indicate that the decrease in male sexual behavior and the infertility associated with exposure to fenarimol were, most likely, due to inhibition of aromatase activity within the central nervous system.

Pharmacology of antiandrogens

Principally, antiandrogens affect all androgen-dependent organs and functions as for instance accessory sexual glands, spermatogenesis, skin and skin appendages, libido and potency, male sexual differentiation, longitudinal bone growth and bone maturation. Pharmacologically, it is important to distinguish between the steroidal antiandrogens of the cyproterone acetate type and the nonsteroidal pure antiandrogens (flutamide, anandrone). For the clinical use of cyproterone acetate and similar antiandrogens in both men and women the three main properties are important: Cyproterone acetate is antiandrogenic, it is a quite potent progestogen and it is antigonadotrophic. Based on pharmacological and biochemical backgrounds cyproterone acetate is used in the following indications: Androgen mediated disorders of the skin such as acne, seborrhoea, hirsutism, alopecia, advanced prostatic carcinoma, precocious puberty and male hypersexuality. In order to avoid undesired systemic side effects local application of antiandrogens, e.g. of cyproterone acetate, has been tried several times. All these attempts have failed probably because insufficient concentration of the antiandrogen at the pilo sebaceous unit. 17 alpha-propylmesterolone is active when given topically (hamster ear model) and has no systemic antiandrogenic effects. This antiandrogen is highly lipophilic and does penetrate preferentially through the hair follicle as has been shown by autoradiography.

Lectin staining of rat testis and epididymis: effect of cyproterone acetate and testosterone

Control and castrated (C) adult rats were treated with cyproterone acetate (CA), testosterone (T) or their combination (CA + T) for 15 days and the affinity of the testicular and epididymal tissue for seven rhodamine-conjugated lectins was analysed in fluorescence microscopy. In the testis CA caused the appearance of degenerating cells in the basal part of the seminiferous epithelium. These cells (spermatogonia, early spermatocytes) appear to be the most vulnerable germinal cells to anti-androgen treatment and this effect could be prevented by simultaneous administration of T. Castration caused a marked reduction in lectin staining of principal and light cells of distal caput (Dcp) and distal cauda (Dcd) epididymidis accompanied by the disappearance of the intratubular sperm mass. In castrated animals CA caused a moderate and T as well as CA + T a marked increase in the stainability of these cells and the appearance of homogeneous secretory material in the tubules. This material gave moderate or strong affinity for most of the lectins. Some minor differences were found in the staining pattern of the cells and the secretory material in Dcp and Dcd as well as after different treatments. This is consistent with local and qualitative differences in the epididymal secretory and absorptive activity, which can be further modified by the hormonal milieu.

Effect of cyproterone acetate on adrenocortical function in children with precocious puberty

Seven children with precocious puberty were treated with cyproterone acetate and their adrenal function studied. In each child the drug caused significant adrenal hypofunction which was secondary to adrenocorticotrophic hormone suppression. None of these children had clinical evidence of adrenal hypofunction and it is assumed that the drug has glucocorticoid-like properties. Children receiving cyproterone acetate should carry information to warn doctors of this effect since they may require steroid cover during illness.

Rouleau formation and fertility of spermatozoa in guinea pigs treated with cyproterone acetate

The effects of cyproterone acetate (CA) on fertility of spermatozoa and rouleau formation were investigated in male guinea pigs. Twelve of 15 matings during CA treatment resulted in pregnancy even when rouleaux were absent in ejaculates, indicating that the rouleau condition is not necessary for the fertilizing ability of guinea pig spermatozoa. Examination of epididymides and vasa deferentia revealed that rouleaux diminished progressively with treatment time and were absent in the excurrent ducts of all males during the eighth and ninth weeks of treatment. Following a latent period after treatment, rouleaux were first noted in a specific epididymal region and were present throughout the distal excurrent ducts and ejaculates by 6 wk posttreatment. This sequence of rouleau loss and reappearance in the excurrent ducts suggests that rouleau formation is dependent on a regional epididymal influence that requires androgens. Spermatogenesis was not arrested; however, seminal vesicle and body weights were reduced in treated males.

Maintenance of sexual behavior in castrate male SW mice using the anti-androgen, cyproterone acetate

The present study was designed to test the hypothesis that cyproterone acetate (C) might selectively block the actions of dihydrotestosterone (D) and via this action, function as an anti-androgen in male sexual behavior. Sexually experienced male SW mice, a strain previously shown to respond to D following castration, were divided randomly into six groups. Beginning on the day after castration, animals received SC injections for 21 days of either testosterone (T), (D), (C), (T+C), (D+C) or vehicle (V). C was found to significantly reduce seminal vesicle and body weights in all androgen treated groups. There was no evidence to support the contention that C selectively blocks the action of D. To the contrary, in sex tests C maintained palpations, thrust mounts, with intromissions and mounts with ejaculations. Indeed, only animals receiving C alone or in combination with T and D exhibited ejaculations throughout the testing. These results suggest that in the SW mouse, C can work like an androgen in the maintenance of male sexual behavior.

The LH response to LH releasing hormone in children with true isosexual precocious puberty treated with cyproterone acetate

Fourteen girls and one boy with isosexual precocious puberty were submitted to LHRH stimulation tests, during and without therapy with cyproterone acetate. In addition, fourteen girls with isosexual precocious puberty not receiving any therapy were tested and served as controls. It was found that cyproterone acetate induces suppression of the responsiveness of the pituitary gland to secrete LH on LHRH stimulation. Daily oral therapy was found to be more effective than the regimen of intramuscular depot injections. These findings demonstrate that cyproterone acetate has an antigonadotrophic effect.