Antagonistic effects of dihydrotestosterone and cyproterone acetate on the synthesis of RNA
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Dihydrotestosterone
Cyproterone
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The effect of castration, androgen and antiandrogen treatment on bone protein content of femoral diaphyses of male mice was investigated. Castration as well as administration of 2.5 mg of cyproterone acetate for 21 days reduced significantly the protein content of the bone. Testosterone fully compensated the bone protein depletion seen in castrates. Simultaneous administration of both cyproterone acetate and testosterone to castrates blocked the testosterone action. The data show that the mice bone matrix is a highly androgen dependent tissue.
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Cyproterone acetate (6-chloro-17-acetoxy -1Α,2Α- methylene – 4,6-pregnadiene-3,20-dione) is the strongest antiandrogen known. Beside its androgenicity, this steroid has a strong progestational and thereby a partial antigonadotropic effect. There is vast evidence that the antiandrogenic effect is mainly due to competitive antagonism with androgens at the receptor sites of target organs. Experimental efforts aimed at two directions: (1) Possibilities for clinical use were evaluated and (2) cyproterone acetate was used as a tool for further investigation of testosterone-dependent events, e.g. androgen-dependent processes in the course of sexual differentiation. Almost all androgen-dependent organs and organ systems are affected by cyproterone acetate. Its most important effects in animals and humans are summarized in the following table: Since cyproterone acetate is also a potent progestagen, it could be used in combination with an estrogen as a hormonal contraceptive for women. Its antiandrogenicity would have positive effects in the so-called gestagen/androgen type of women. For use in men, only those antiandrogens would be suitable that have not only antiandrogenic but also gestagenic, hence antigonadotropic properties like cyproterone acetate. ‘Pure’ antiandrogens lacking these partial effects stimulate the secretion of gonadotropins and cause thereby enhanced synthesis and secretion of androgens which would compensate for antiandrogenic effects.
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Total testosterone concentrations in the serum of patients treated with antiandrogens were measured by means of an industrially produced radioimmunological testosterone assay kit (VEB Sächsisches Serumwerk Dresden). Antiandrogen therapy using cyproterone acetate (Androcur) leads to a reduction in serum testosterone concentration which is significant at the p less than 0.01 level. The data suggest that testosterone concentrations vary inversely with increasing Androcur dosage; they are around 7 nmol/l at the doses conventionally administered. The testosterone concentrations obtained under depot-Androcur treatment suggest that intervals between injections should be less than 10 days.
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Abstract The objective of this study was to identify specific physiologic parameters in crustaceans that are targeted by chemicals known to be antiandrogenic in vertebrates. We hypothesized that chemicals capable of binding to the vertebrate androgen receptor would also elicit toxicity to crustaceans by binding to specific steroid hormone receptors in an antagonistic manner. This hypothesis was tested by evaluating the effects of the antiandrogen cyproterone acetate on growth, molting, sexual differentiation, and reproduction of Daphnia magna. Exposure of daphnids to concentrations of cyproterone acetate appreciably below those that elicited mortality reduced growth but had no effect on molting. These concentrations of cyproterone acetate had no effect on various developmental and maturation parameters. Cyproterone acetate also reduced the number of offspring produced by parthenogenetically reproducing daphnids, but this effect appeared to be a consequence of the reduced size of the daphnids and their inability to accommodate a brood of more than approximately 10 eggs. These results indicate that the antiandrogen cyproterone acetate specifically targets a process critical to growth of daphnids that is independent of molting. Additional studies are warranted to established whether this is an endocrine-related toxicity to crustaceans that is associated with environmental antiandrogens such as some pesticide metabolites.
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Antiandrogens, such as cyproterone acetate, and oestrogens both inhibit sebaceous secretion in rats and have a potentiality for the treatment of hirsutism and acne in the human female. However, they act at different points. In castrated rats treated with testosterone, 3 μg/day oestradiol produced a greater decrease in sebum secretion than a dose of cyproterone acetate over 1000 times larger; moreover the antiandrogen reduced the incidence of sebaceous mitoses whereas the oestradiol did not. In hirsute women, oral administration of 100 mg of cyproterone acetate daily caused a 40% reduction in sebum secretion within 10 days; a further 20% was subsequently produced by combined therapy with cyproterone acetate and ethinyloestradiol. Significant decreases in the diameter and rate of growth of thigh hairs were not established until around the fourth monthly cycle of treatment. The actions were believed to be mainly peripheral, though contributory factors could also have been the small but significant reductions in plasma androgens produced by the antiandrogen, and the marked rise in sex hormone binding globulin produced by the oestrogen. That it is theoretically possible for cyproterone acetate or oestradiol to act locally follows from an unequivocal demonstration that either compound produced a local depression of sebum secretion when applied topically to rats.
Cyproterone
hirsutism
Antiandrogens
Sebaceous gland
Flutamide
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Cyproterone
Sebaceous gland
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Cyproterone
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Cyproterone
Concomitant
Androgen Suppression
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