William G. Luttge

Testosterone, androstenedione and dihydrotestosterone: Effects on mating behavior of male rats

Abstract The relative effectiveness of testosterone, androstenedione, and dihydrotestosterone in maintaining mating behavior following castration of male rats was studied. In Experiment 1 testosterone, but not dihydrotestosterone, was found to maintain mating. In Experiment 2 testosterone and androstenedione were found to be equally effective in maintaining mating. Dihydrotestosterone failed to maintain mating and was no more effective than no treatment at all. Testosterone, androstenedione, and dihydrotestosterone significantly enhanced seminal vesicle and penis weight. In Experiment 3 castrated male rats were administered radiolabeled testosterone, androstenedione, or dihydrotestosterone. Radioactivity was found in hypothalamic and seminal vesicle samples indicating that these steroids can be accumulated by brain as well as peripheral androgen-sensitive tissues. It was concluded that the peripherally active steroid dihydrotestosterone probably plays no role in the maintenance of sexual behavior.

Differential localization of progesterone uptake in brain, role od sex, estrogen pretreatment and adrenalectomy

Abstract In 3 experiments gonadectomized male and female rats were administered tritiated progesterone. Brain tissues were analyzed for the retention of radioactivity using liquid scintillation techniques. Experiment 1. Estrogen-primed rats were sacrificed 30 min or 60 min after progesterone treatment. There was an increasing gradient of radioactivity from anterior hypothalamus through posterior hypothalamus to the region of the cerebral peduncle in the mesencephalon. Radioactivity levels were higher in females than in males only in anterior hypothalamus and plasma. Experiment 2. Estrogen-primed and non-estrogen-primed rats were sacrified 60 min after progesterone treatment. Estrogen priming had no influence on the retention of radioactivity. The mesencephalic sample retained more radioactivity than the diencephalic tissues. Tissues from females retained more radioactivity than tissues from males. Experiment 3. Adrenalectomized and sham-operated animals were sacrificed 60 min after progesterone treatment. Adrenalectomized animals retained from 27.6 to 51.3% more radioactivity than control animals. Mesencephalic tissues retained more radioactivity than diencephalic tissues. The results suggest the existence of limited capacity binding sites for progesterone in the mesencephalon and diencephalon as well as the pituitary.

Neonatal androgenization and the development of estrogen responsivity in male and female rats

Abstract Male and female rats castrated in adulthood, male rats castrated on the day of birth, and female rats administered 250 μg of testosterone propionate on the day of birth were administered various doses of estradiol benzoate in adulthood and tested for the display of lordosis. The females and neonatally castrated males exhibited a dose-dependent response to estrogen. The control males and neonatally androgenized females showed few lordosis responses when mounted by nonexperimental males regardless of the dose of estrogen administered. The combination of progesterone with the estrogen treatment did not facilitate lordosis responding in the males and neonatally androgenized females, nor did an extensive adaptation period to the test arena, nor did 10 days of treatment with 200 μg estradiol benzoate daily. It was concluded that males and neonatally androgenized females are less responsive to estrogen in adulthood than are females and neonatally castrated males.

P-chlorophenylalanine methyl ester: an aphrodisiac?

P-Chlorophenylalanine methyl ester and the ester plus pargyline have been reported to facilitate sexual mounting behavior in animals, but these studies have shown only a facilitation of homosexual mounting. The present study indicates that these agents do not enhance the probability or frequency of heterosexual interactions in rats.

Anti-estrogen inhibition of androgen induced sexual receptivity in rats.

It has been known for some time that the administration of testosterone propionate or testosterone propionate plus progesterone can induce lordosis behavior in female rats much as can estrogen treatment. It has been suggested that this phenomenon reflects an androgen to estrogen metabolism of the administered testosterone. In the present study it was argued that if this hypothesis were true it should be possible to block androgen induced lordosis with an anti-estrogen which is known to block estrogen induced lordosis. Ovariectomized female rats were administered either testosterone propionate plus progesterone or testosterone propionate plus anti-estrogen plus progesterone. Androgen treatment led to the display of lordosis; anti-estrogen blocked androgen induced lordosis. The anti-estrogen used was CI-628 (CN 55,945-27, Parke, Davis). When this anti-estrogen was administered to male rats it failed to block androgen maintained seminal vesicle weight, or normal male mating patterns suggesting that this agent does not possess anti-androgenic properties. The data are consistent with the hypothesis that androgen induces female lordosis patterns by first being converted to estrogen.

Early androgen treatment and male sexual behavior in female rats

Abstract Stimulation of the newborn male rat by endogenous testicular hormones and stimulation of the newborn female rat by exogenous testosterone will permanently suppress the rats potential to respond to estrogen and progesterone with the display of feminine sexual behavior. Thus, early hormone stimulation de-feminizes the rat. Some data suggest that early testosterone stimulation may also enhance masculine sexual behavior and the reactivity of the adult rat to testosterone. Three experiments were conducted to evaluate this latter hypothesis. In Experiment 1 female rats were treated with oil at birth, with testosterone at birth, 96 hr after birth or 192 hr after birth. This postnatal testosterone stimulation did not increase the frequency of mounting behavior in response to testosterone treatment in adulthood. In Experiment 2 female rats were treated with testosterone or oil on Day 17 of gestation. This prenatal testosterone treatment did not increase the frequency of mounting behavior in response to testosterone treatment in adulthood. In Experiment 3 female rats were treated with testosterone or oil on Days 16–20 of gestation and 96 hr after birth. This prenatal and postnatal testosterone treatment did not increase the frequency of mounting behavior in response to testosterone treatment in adulthood. It was concluded that early testosterone stimulation does not enhance the rats potential to display masculine sexual behavior or its reactivity to testosterone in adulthood.

Role of the adrenal in the preferential accumulation of progestin by mesencephalic structures.

Abstract Adrenally-intact and adrenalectomized female rats were administered tritiated progesterone. One hour later the radioactivity levels in diencephalic structures, anterior and posterior hypothalamus and in mesencephalic structures, “cerebral peduncle” and reticular formation were assessed. Mesencephalic tissues accumulated more radioactivity than diencephalic tissues. This differential was particularly evident in the adrenalectomized animals. These findings may provide insight into the role of progesterone in the induction of sexual receptivity and into the anesthetic effects of this steroid.

Regional localization of estrogenic metabolites in the brain of male and female rats

Abstract The female rat, but not the male, responds to estrogen stimulation in adulthood with the display of lordosis, the characteristic mating posture in this species. This male-female difference in response to estrogen reflects an androgen-induced sexual differentiation process. To obtain additional information about the nature of this difference adult gonadectomized male and female rats were administered 3 H-estradiol and sacrificed two hours later. Brain and pituitary samples were taken for analysis. The samples were subjected to steroid extraction and thin-layer chromatography. The anterior hypothalamus and pituitary were found to contain predominantly estradiol. The posterior hypothalamus, however, contained significant amounts of both estradiol and estrone, suggesting a functional difference between these two brain loci. No male-female differences in the regional distribution of estrogenic metabolites were found, however.

Long-term retention of tritiated estradiol in brain and peripheral tissues of male and female rats.

Gonadectomized male and female rats were administered tritiated estradiol intravenously and sacrificed either 2 h or 24 h later. Samples of brain cortex, hypothalamus, and pre-optic-diagonal band regi

Partial deferminization by administration of androstenedione to neonatal female rats

Abstract The repeated administration of 500 μg androstenedione to neonatal female rats at 48, 72, 96, and 120 hours after birth results in the inhibition of corpora lutea production and cyclic vaginal cornification. However, unlike the defeminization produced by high doses of testosterone propionate these females have essentially normal female-like sexual behavior.