Failure of 5alpha-dihydrotestosterone to initiate sexual behaviour in the castrated male rat

Inhibition of dihydropteridine reductase by catechol estrogens

Catechol estrogens, such as 2-hydroxyestriol, 2-hydroxyestradiol, and 2-hydroxyestrone, inhibit human liver dihydropteridine reductase noncompetitively with Ki values ranging from 1.5 to 4.6 X 10(-6)M. Catechol estrogens lose approximately half of their inhibitory potency if the C-2 hydroxyl groups are methylated. Thus, 2-methoxyestrogens have inhibitory potencies equivalent to those of their parent estrogens--estriol, estradiol, and estrone. Aromatization of ring B or stereoisomerism at C-17 does not affect the inhibitory potency of estrogens, although stereoisomerism at C-16 enhances the inhibitory potency of estriol. These results support the hypothesis that catechol estrogens may interfere with catecholamine metabolism by acting as inhibitors of enzymes involved in catecholamine metabolism, such as dihydropteridine reductase.

Therapeutic sex drive reduction

Sex drive reducing therapies are employed in those cases of anomalous erotic preferences in which the patient's sexual behaviour is dangerous (certain forms of sadism, or a preference for forcing intercourse or similar interaction) or while not really dangerous, is utterly unacceptable to the community (pedophilia and pedohebephilia) or is an embarrassment to the patient himself (exhibitionism). Three sex drive reducing therapies are in use, all designed for male patients, (1) pharmacological reduction of circulating testosterone, (2) orchidectomy, (3) deletion of certain brain structures by stereotaxic surgery. The main indication for pharmacological sex drive reduction is exhibitionism but here it should be used only temporarily, as a first emergency measure, and after that only intermittently, during periods when the patient can not manage his urges by techniques he should be taught by a behaviour therapist. In cases of unmanageable and dangerous sadism, orchidectomy is the method of choice--and the same would appear to be true for particular cases of pedohebephilia. Brain surgery in this realm is not yet based on sufficient knowledge and should be thoroughly studied on infrahuman primates, before use with humans could be seriously considered.

Differentiation of coital behavior in mammals: a comparative analysis

The evidence reviewed suggests that in all mammalian species the adult male's ability to display masculine coital behavior depends in part on exposure of the developing brain to testicular testosterone or its metabolites. In many mammals, particularly rodents, ruminants, and some carnivores, perinatal exposure to androgen also causes behavioral defeminization, i.e., reduced capacity to display typically feminine coital behavior in response to gonadal hormones in adulthood. The data reviewed suggest that no such process occurs in certain other mammalian species, including ferret, rhesus monkey, marmoset, and man. Testicular androgen may cause behavioral defeminization only in those species in which expression of feminine sexual behavior normally depends on the neural action of progesterone, acting synergistically with estradiol; new data support this claim in the ferret. The possible contribution of estrogenic and 5 alpha-reduced androgenic metabolites of testosterone to the occurrence of behavioral masculinization and defeminization is considered in those mammalian species for which data are available.

Male pseudohermaphroditism due to steroid 5-alpha-reductase deficiency

A new inherited form of male pseudohermaphroditism has been investigated in a pedigree of 24 families with 38 affected males. At birth, the affected males (46 XY) have a clitoral-like phallus, bifid scrotum and urogenital sinus. The testes are in the inguinal canals or labial-scrotal folds. The Wolffian structures are normally differentiated; there are no Mullerian structures. At puberty a muscular male habitus develops with growth of the phallus and scrotum, voice change and no gynecomastia. The subjects have erections, ejaculations and a libido directed towards females. They have decreased body hair, a scant to absent beard, no temporal hair line recession and a small prostate. Testicular biopsy reveals a normal testis. The mean plasma T levels in affected adults are significantly higher, and the mean plasma DHT levels are significantly lower when compared to those in normal subjects. The plasma T:DHT ratios range from 35 to 84 compared to 8 to 16 in normal subjects. After the administration of hCG, the T:DHT ratios in affected male children range from 74 to 162 compared to 3 to 26 in the control subjects. In affected adults, mean plasma LH and FSH levels are significantly higher than in normal subjects. In the affected subjects, the metabolic clearance rates of T and DHT are normal, but the conversion ratio of T to DHT is less than 1 per cent. The endogenous mean urinary E:A and E-OH:A-OH ratios, and the urinary E:A and E-OH:A-OH ratios after the infusion of radioactive T are significantly higher than in normal males. Inheritance is autosomal recessive with some sibling sisters showing the same biochemical defect, and obligate carrier parents showing an intermediate defect. These data support our thesis that the defect in these male pseudohermaphrodites is secondary to decreased steroid delta 4-5 alpha-reductase activity. The affected subjects provide a clinical model for delineating the roles of T and DHT in sexual differentiation and development. This entity also demonstrates an inherited disorder of steroid metabolism in which the basic enzyme deficiency resides in the target tissues.

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.

Effects of anti-estrogens on testosterone stimulated male sexual behavior and peripheral target tissues in the castrate male rat

In the first experiment castrated male rats were injected daily with either vehicle or 800 mug testosterone together with either 6 hr pretreatment or concurrent treatment with the anti-estrogens CI-628 (4 mg) or MER-25 (20 mg). The only treatment found to significantly reduce male copulatory behavior was concurrent treatment with CI-628. Anti-estrogen treatment was also found to slightly reduce body weights, increase seminal vesicle weights in response to testosterone and to have no significant effects on androgen stimulated increases in penis weight and length. In the second experiment castrated male rats were injected daily with either vehicle or 500 mug testosterone together with 2.5 mg injections of CI-628 given 6 hr before and concurrent with the androgen injections. The anti-estrogen treatment was found to markedly inhibit the desplay of male sexual behavior, to reduce body weights, and to stimulate seminal vesicle weights. Penile weights and lengths were again not effected by the anti-estrogen therapy. These results were interpreted as supporting the theory that testosterone stimulated male sexual behavior in the rat following its aromatization to estradiol in the brain.

Subcellular analysis of the accumulation of estrogen by the brain of male and female rats

Three experiments were preformed to provide additional information on the interaction of estrogen with subcellular components of the brain of male and female rats. In experiment 1 tritiated estradiol was administered to adult gonadectomized male and female rats which were then sacrificed 15,60 or 120 min later. Hypothalamic, cortical and pituitary samples were taken and were separated into nuclear and cytosol fractions. For the hypothalamic tissue from females nuclear concentration of radioactivity increased throughout the 2 h period while for males nuclear concentration rose during the first h and then declined. There was a significant sex difference in hypothalamic nuclear concentration of estrogen, male levels being lower. For both sexes cytosol levels progressively declined. For cortical tissue, nuclear radioactivity levels were low and relatively constant for both sexes, while cytosol levels fell during the 2 h period. Pituitary tissue showed a pattern in both nuclear and cytosol fractions which resembled the hypothalamic pattern although absolute levels were higher in the nuclear fraction. In experiment 2 male and female rats were administered labeled and unlabeled estradiol concurrently and were sacrificed 60 and 120 min later. Radioactivity levels were reduced in hypothalamic and pituitarynuclei, but not in cortical nuclei in comparison with animals not administered unlabeled hormone. In experiment 3 males and females were administered tritiated estradiol and were sacrificed 2 h later. The brain of each animal was split longitudinally. One half of each hypothalamic and cortical sample was subjected to nuclear separation while the other half was digested in tissue solubilizer before radioactivity counting. The former procedure showed a substantially greater nuclear concentration of radioactivity for hypothalamic tissue from females than from males. The whole tissue analysis showed only a slight sex difference for hypothalamic tissue. Sex differences were small by either procedure for cortical tissue. It was concluded that the hypothalamus of both male and female rats contains a limited capacit nuclear binding system for estrogen, but that the system is quantitatively less effective in binding estrogen in males.