Showing papers on "Testosterone published in 1973"
TL;DR: Castrated male rats injected daily with 2 micrograms of estradiol benzoate (EB) combined with 200 microgramS of dihydrotestosterone propionate (DHTP) displayed masculine mating behavior which was indistinguishable from that of other castrates treated with 200 milligrams of testosterone propionates.
Abstract: Castrated male rats injected daily with 2 micrograms of estradiol benzoate (EB) combined with 200 micrograms of dihydrotestosterone propionate (DHTP) displayed masculine mating behavior which was indistinguishable from that of other castrates treated with 200 micrograms of testosterone propionate (TP). Significantly less copulation was seen in rats treated with either 4 micrograms of TP plus 200 micrograms of DHTP or 2 micrograms of EB. Mating in male rats may depend on the action of both estrogenic and 5alpha-dihydro metabolites of testosterone.
289 citations
TL;DR: It is found that many potent synthetic androgens can bind directly to β protein and to prostate cell nuclei without a metabolic conversion, indicating that the bulkiness and flatness of the steroid molecule play a more important role in receptor binding than the detailed electronic structure at the Δ4 bond of Ring A.
255 citations
TL;DR: In this article, the mean androstenedione level during the middle third of the menstrual cycle was significantly higher than during the earlier (p < 0.01) or later portions.
Abstract: Utilizing specific radioimmunoassays serum androstenedione, testosterone, follicle stimulating hormone (FSH), and luteinizing hormone (LH) were measured daily in the same aliquots of sera in 6 ovulatory menstrual cycles. In 3 of 6 cycles a progressive increase in serum androstenedione concentration was seen during the follicular phase. The mean androstenedione level during the middle third of the menstrual cycle was significantly higher than during the earlier (p < 0.01) or later (p < 0.001) portions. Serum testosterone levels in the same individual cycles showed random variations. Again the mean T level was significantly higher (p < 0.001) during the middle third as compared to either the beginning or end of the menstrual cycle.
232 citations
TL;DR: Decapsulated intact rat testes are highly sensitive to gonadotrophic stimulation in vitro, responding to HCG concentrations as low as 0.1 ng ml−1 (10−12 M) with synthesis and release of testosterone and to higher concentrations with synthesisand release of cyclic AMP.
Abstract: GONADOTROPHIN receptor sites with high specificity and affinity for luteinizing hormone (LH) and human chorionic gonadotrophin (HCG) have been demonstrated in particulate and soluble interstitial cell fractions of rat testis1–4. Such hormone binding sites have been used in radioligand receptor assays for LH and HCG1,2 and in studies on the structural determinants of gonadotrophin binding to target tissue5–7. Other parameters of gonadotrophin action have been examined during incubation of intact rat testes with HCG by radioimmunoassay of the cyclic AMP and testosterone produced during trophic hormone stimulation in vitro8–11. Decapsulated intact rat testes are highly sensitive to gonadotrophic stimulation in vitro, responding to HCG concentrations as low as 0.1 ng ml−1 (10−12 M) with synthesis and release of testosterone and to higher concentrations with synthesis and release of cyclic AMP10. Release of cyclic AMP during incubation with HCG has been shown to reflect cyclic AMP synthesis by simultaneous measurement of 14C-adenine incorporation and radioimmunoassay of cyclic AMP9,10.
225 citations
TL;DR: Male pseudohermaphroditism resembling testicular feminization develops in animals that are deprived of androgens in utero by one of the several mechanisms, including castration, defective testosterone synthesis, and exposure to pharmacologic agents that either block androgen biosynthesis in the testis or androgen action at the end organ.
Abstract: Publisher Summary This chapter discusses androgen metabolism and the mechanism of action in male pseudohermaphroditism. It has been found that testosterone is the major androgen secreted into the blood of most mammals and that this steroid has biological actions on many tissues. As animals with testicular feminization cannot respond to androgens in utero, tissues, such as prostate, Wolffian duct derivatives, and external genitalia, do not differentiate, and the tfm animal develops as a male pseudohermaphrodite. Male pseudohermaphroditism resembling testicular feminization also develops in animals that are deprived of androgens in utero by one of the several mechanisms, including castration, defective testosterone synthesis, and exposure to pharmacologic agents that either block androgen biosynthesis in the testis or androgen action at the end organ. When the gonaducts and external genitalia fail to undergo androgen-dependent differentiation in utero, they do not develop into a normal reproductive tract when subsequently exposed to large doses of androgens. Thus, certain tissues may acquire insensitivity to androgens during differentiation. The chapter also discusses ultrastructural examination of the interstitial area of vet rat testes that demonstrates increased peritubular connective tissue. The interstitial tissue consisted predominantly of fibroblasts and a few peritubular sheath cells.
182 citations
TL;DR: Evidence is provided that human fetal testicular tissue accumulates testosterone in a pattern suggesting higher androgen production at the time of male genital differentiation.
Abstract: Testosterone and estradiol concentrations were measured by isotope-displacement assays in the gonads and adrenals of 54 human fetuses (33 male, 21 female) delivered by hysterotomy. Results were correlated with crownrump (CR) length which ranged from 5 to 24 cm, corresponding to 10–25 weeks fetal age. Testosterone concentration averaged 1400 pg/mg in the testes but was negligible (<90 pg/mg) in the ovaries and in the adrenals of both sexes. Testosterone was found in appreciable amounts in the testes from the youngest specimens, reached a peak at 7–10 cm CR-length and declined by 13–14 cm CR-length. Little or no estradiol was detected in fetal testes, ovaries and adrenals and there were no sex differences in these levels. These data provide evidence that human fetal testicular tissue accumulates testosterone in a pattern suggesting higher androgen production at the time of male genital differentiation.
175 citations
TL;DR: The data support the concept that although there is a specific seminiferous tubular factor regulating F SH secretion, testicular steroids also modulate FSH secretion.
Abstract: The effect of sex steroids on plasma concentrations of FSH and LH was studied in 18 men. Steroids were administered by constant infusion for 96 hr at twice the estimated daily production rate of normal men to obtain stable levels in peripheral blood. Testosterone, 15 mg daily, increased plasma testosterone and estradiol levels 2-fold and suppressed FSH and LH approximately 40% during the 3rd and 4th days of infusion. Infusion of estradiol, 90 μg daily, caused similar suppression of FSH and LH (approximately 30%), and addition of 17α-hydroxyprogesterone, 4.5 mg daily, to the estradiol, 90 μg daily, had no additive effect. Dihydrotesterone, in pharmacologic dosage (7.5 mg daily) produced no detectible changes in plasma FSH or LH. There was no evidence for a selective effect of any of the steroids on FSH secretion. This study supports our previous concept that although there is a specific seminiferous tubular factor regulating FSH secretion, testicular steroids also modulate FSH secretion.
165 citations
TL;DR: This work has shown that testicular androgen is essential for the completion of spermatogenesis in the seminiferous tubules and for the acquisition of fertilising capacity in the epididymis.
Abstract: Testicular androgen binding protein (ABP) is produced by the testis (1–3), presumably by the Sertoli cells, secreted into the testicular fluid and carried to the epididymis by way of the efferent ducts. ABP is completely dependent on FSH stimulation; it disappears rapidly after hypophysectomy and is dramatically stimulated by FSH (4), but not by LH or androgen alone. In the hypophysectomized rat, the accumulation of ABP in response to FSH is greatly enhanced by treatment with androgen.
146 citations
146 citations
TL;DR: The results indicate that Eb or Tp inhibited release of LH in castrate rats of both sexes, and males were more sensitive to the inhibitor effect of the low dose of Tp than females.
Abstract: The effects of single sc injections of various doses of estradiol benzoate (Eb) and testosterone propionate (Tp) on plasma levels of LH, FSH and prolactin have been reinvestigated in castrate rats of both sexes. Our results indicate that Eb or Tp inhibited release of LH in castrate rats of both sexes. Males were more sensitive to the inhibitor effect of the low dose of Tp than females. The steroids also lowered plasma FSH levels in spayed females; however, in castrated males Eb stimulated FSH release and a decrease in FSH followed the injection of only the highest dose (2 mg) of Tp. Eb and Tp had a synergistic effect in inhibiting FSH release in the male. Both steroids stimulated release of prolactin in castrate males and females (no sex difference in release of prolactin in response to Eb was observed; however, males appeared more sensitive to Tp treatment). Single injections of progesterone (P) in spayed females produced variable results. High doses inhibited LH release and elevated prolactin levels. Ef...
145 citations
TL;DR: Testes of fetal rats possess the enzymes necessary for converting radioactive acetate to radioactive testosterone as early as 15.5 days of intrauterine life, and the fetal testis is capable of formation do novo of testosterone through the period of sexual differentiation of the internal genitalia.
Abstract: Testes of fetal rats possess the enzymes necessary for converting radioactive acetate to radioactive testosterone as early as 15.5 days of intrauterine life. The fetal testis is, therefore, capable of formation do novo of testosterone through the period of sexual differentiation of the internal genitalia. Testosterone was measured in testicular tissue of fetal rats. Values ranged from as low as 0.09 ng/mg at 15.5 days of gestation to 2.76 ng/mg at 18.5 days of gestation. The sharp rise at 18.5 days of fetal age coincides with morphological evidence that relatively large amounts of testosterone are necessary for Wolifian duct stabilization at this time. Fetal testes were also incubated with [‘4C] acetate or [‘H] pregnenolone. Whereas conversion of both substrates to radioactive testosterone occurred at 15.5 and 16.5 days of gestation, no such conversion was evident at 14.5 days of fetal age with either substrate. Nonradioactive testosterone was, however, measurable in incubation from all three time periods. Neither radioactive nor nonradioactive testosterone was detectable in incubations of fetal ovaries with radioactive acetate or pregnenolone at 15 to 20 days of gestation. The influence of steroid androgens on
TL;DR: The patterns and levels of the steroids observed in the adrenalectomized subject suggest the following when compared to patterns and Levels of the same steroids during menstrual cycles of intact women.
Abstract: In order to assess the ovarian contribution to peripheral steroid levels during the menstrual cycle, the serum levels of various steroids were measured daily during a complete menstrual cycle in a bilaterally adrenalectomized woman. The following steroids were measured: progesterone (P), 17-hydroxyprogesterone (17-OHP), pregnenolone (5Δ-P), 17-hydroxypregnenolone (17-5Δ-P), dehydroepiandrosterone (DHEA), it's sulfate (DHEA-S), testosterone (T), 5α-dihydrotestosterone (DHT), androstenedione (A), estrone (E1), estradiol-17β (E2), and cortisol. Plasma cortisol and 17-5Δ-P were undetectable throughout most of the study period. However, the remaining steroids studied were measurable. The patterns and levels of the steroids observed in the adrenalectomized subject suggest the following when compared to patterns and levels of the same steroids during menstrual cycles of intact women. The progestins, P and 17-OHP, are secreted by the ovary not only during the luteal phase but also throughout the follicul...
TL;DR: Data indicate that the fetal testis of the monkey is the source of the elevated levels of testosterone, and the sex difference in the amounts of T found on day ISO to 156 of gestation is abolished.
Abstract: A radioimmunoassay was developed for measuring testosterone (T) in the plasma of the rhesus monkey (Macaca mulatto). The method is sensitive and specific and can distinguish 20 pg of T when added to plasma from the adrenalectomized- ovariectomized monkey. When plasma obtained from cord blood at various times during gestation was analyzed by this method, the levels of T in plasma from the umbilical artery of males were significantly higher than those in females. Plasma from females did, however, contain small amounts of this hormone with little variation between animals. Large fluctuations in the concentrations of T in plasma from the fetal male were observed. Significantly higher amounts of T were found in the umbilical artery than in the vein in male but not in female fetuses. Castration of the fetus on day 100 of gestation abolished the sex difference in the amounts of T found on day ISO to 156 of gestation. These data indicate that the fetal testis of the monkey is the source of the elevated levels of ...
TL;DR: Correlation of data with plasma androgen levels from this patient's peripheral and spermatic veins led the authors to conclude that, as in lower species, high local levels of androgen will initiate spermatogenesis in man.
Abstract: Morphologic and steroid biochemical studies were performed on surgical specimens from a 6-yr-old boy with a Leydig cell tumor. Active spermatogenesis to early spermatid stage was found in the testicular tissue of the tumorbearing testis, and absence of spermatogenesis was observed in a biopsy of the contralateral testis. Tumor tissue actively metabolized tritiated progesterone, pregnenolone and cholesterol to testosterone and androstenedione.1 Correlation of these data with plasma androgen levels from this patient's peripheral and spermatic veins led the authors to conclude that, as in lower species, high local levels of androgen will initiate spermatogenesis in man.
TL;DR: In order to establish the normal diurnal variation in both sexes, plasma steroid levels were measured at 20-min intervals throughout the day in a normal man and a preovulatory woman.
Abstract: A method for measuring cortisol, corticosterone, testosterone, progesterone, and 17-OH progesterone simultaneously in 2 ml of plasma has been developed especially for episodic secretion studies in which many frequent assays are required. Steroids were extracted from plasma, separated into 4 fractions by paper chromatography, and individual steroids in each fraction were measured by radioimmunoassay. The individual steroid radioimmunoassays were demonstrated to be sensitive, specific, accurate, and precise. Base line 8 AM plasma steroid levels were measured in normal males and menstruating females both before and after ovulation. The values obtained were in good agreement with those previously reported by other investigators using different methods. In order to establish the normal diurnal variation in both sexes, plasma steroid levels were measured at 20-min intervals throughout the day in a normal man and a preovulatory woman. When plasma steroid levels were plotted against time frequent intermittent pea...
TL;DR: Failure of prostate wt to respond to LH stimulation was not due to interference with testosterone action, and the minimal effective dose of testosterone required to increase prostate wT was identical in immature and mature animals.
Abstract: The sensitivity of the testicular response to exogenous LH and FSH has been evaluated in sexually immature and mature animals. Male rats were hypophysectomized at 21 days of age (weaning) and 87 days of age (sexually mature). Five days later, NIH—LH—B7 was administered daily for 5 days in doses ranging from 0.04-400 μ/100 g bw/day. Sexually immature males showed no response to any dose of LH, while sexually mature animals responded to 0.66 μg and showed a maximal response to 20 μg. However, the sexually immature 5-day hypophysectomized animal responded to NIH—FSH—S4; 8 μg/100 g bw/day, given over 5 days, significantly increased testicular wt, and 300 μg produced a maximal response. FSH alone failed to stimulate prostate wt. The minimal effective dose of testosterone required to increase prostate wt was identical in immature and mature animals. Thus, failure of prostate wt to respond to LH stimulation was not due to interference with testosterone action. Pretreatment of sexually immature, 5-day hypophysect...
TL;DR: Androgen-concentrating cells were found in the midbrain of the chaffinch Fringilla coelebs by autoradiographic results suggest that the nucleus intercollicularis is a site in the action of androgens on avian vocal behavior.
Abstract: Androgen-concentrating cells were found in the midbrain of the chaffinch Fringilla coelebs by autoradiography using tritiated testosterone. Labeled cells were localized primarily in the nucleus intercollicularis, an area from which vocalizations can be electrically stimulated in birds. These autoradiographic results suggest that the nucleus intercollicularis is a site in the action of androgens on avian vocal behavior.
TL;DR: The hypothesis that different androgen metabolites are differentially effective in different target tissues and in the induction of different behaviors in castrate CD-1 and Swiss-Webster mice is supported.
TL;DR: It is concluded that the cause of the depression of spermatogenesis in men given TP is the striking reduction in testicular T.
Abstract: Testicular and plasma testosterone (T) and plasma LH levels were determined in 6 normal men. Two of these men received 50 mg testosterone propionate (TP) daily for 10 and 25 weeks, respectively. Testicular and plasma T and plasma LH assays were again performed during TP administration. The mean T concentration for 5 control testicular biopsies was 553 ng/g ± 90 sd, which was approximately 100 times higher than average normal plasma T concentrations (assuming 1 ml plasma ≅ 1 g tissue). Administration of TP resulted in the following: 1) LH was rapidly reduced to undetectable levels; 2) testicular T decreased by about 95%; 3) plasma T increased nearly 2-fold; and 4) sperm concentration dropped sharply. Since a high concentration of testicular T is known to be required for normal spermatogenesis, we conclude that the cause of the depression of spermatogenesis in men given TP is the striking reduction in testicular T.
TL;DR: There is a definite relationship between plasma testosterone levels and Leydig cell fine structure in seasonally breeding hyrax, and average Leydigs cell volume showed significantly positive correlation with plasma testosterone level.
Abstract: Seasonal changes in plasma testosterone levels and in various testicular parameters were studied in 41 adult male rock hyrax (Procavia habessinica). Among animals collected during the annual breeding season, testis weights and plasma testosterone levels were approximately five times greater than among animals collected outside the breeding season. Light microscopic measurements showed that increase in testis weight was largely due to enlargement of the seminiferous tubules. Histological sampling techniques indicated no significant change in Leydig cell numbers. Leydig cell size increased during the breeding season, and average Leydig cell volume showed significantly positive correlation with plasma testosterone level. With the electron microscope, Leydig cell hypertrophy was seen to involve changes in quantity and structure of several cytoplasmic constituents. Lipid droplets disappeared and smooth endoplasmic reticulum (SER) spread dramatically as the cells increased in size. In contrast to the sparse and heterogeneous assemblage of irregularly tubular and cisternal SER seen in nonbreeding animals, the extensive masses of SER in breeding animals appeared as relatively straight, unbranched tubules of uniform diameter. Peculiar membranous structures, possibly derived from the SER, were abundant in the periphery of Leydig cells from animals with high plasma testosterone levels. These findings suggest that there is a definite relationship between plasma testosterone levels and Leydig cell fine structure in seasonally breeding hyrax.
TL;DR: The growth response induced by testosterone was considerably slower than that by 5α-dihydrotestosterone, indicating that the former is a less potent androgen, and adenosine 3′,5′-monophosphate does not appear to be involved in the effect of androgens on cell proliferation.
TL;DR: Observations suggest that a higher central mechanism is responsible for this early activation of the pituitary—Leydig cell axis during the prepubertal period.
Abstract: Serum LH, FSH and testosterone concentrations were measured in male rats from the early neonatal period through maturity. In four separate studies, there was a distinct LH peak at 17, 17, 19 and 20 days, respectively. In two of these studies there was a concomitant peak of serum testosterone concentration, and in a third study the testosterone peak was one day before the LH peak. FSH increased with LH in two of four studies. To test whether the observed prepubertal peaks of serum LH and testosterone were due to increased pituitary sensitivity to luteinizing hormone—releasing hormone (LH—RH), groups of male rats from 8–26 days old were given graded doses of LH—RH. Serum LH and FSH levels increased to about the same extent in all age groups 30 min after injection of LH—RH. Since the pituitary appeared equally responsive to LH—RH throughout the prepubertal period, these observations suggest that a higher central mechanism is responsible for this early activation of the pituitary—Leydig cell axis.(Endocrinolo...
TL;DR: It was concluded that these androgenic steroids are secreted in a cyclic fashion by the rat ovary.
Abstract: To determine whether cyclic fluctuations in androgen concentrations occur during the 4-day rat estrous cycle plasma testosterone androstenedione and estradiol levels were measured at various times. The techniques consisting of thin-layer chromatography and radioimmunoassay for purifying and quantitating the steroids are described. Estradiol increased on the afternoon of diestrus from 9.1 pg/ml at 1000 hours to 26.7 pg/ml at 1600 hours and reached a peak of 52.4 pg/ml on the afternoon of proestrus significantly higher than at all other times (p<.05). A similar pattern was demonstrated for the androgens with highs of 179 and 211.6 pg/ml for testosterone and androstenedione respectively on the afternoon of proestrus. It was concluded that these androgenic steroids are secreted in a cyclic fashion by the rat ovary.
TL;DR: The response of the isolated rat testis to hCG in vitro was evaluated in terms of cyclic AMP synthesis and release into the incubation medium, indicating that proportionate synthesis and releases occurred during stimulation with hCG.
Abstract: The response of the isolated rat testis to hCG in vitro was evaluated in terms of cyclic AMP synthesis and release into the incubation medium. Simultaneous measurement of 14C adenine incorporation into cyclic AMP and total release of immunoreactive cyclic AMP showed a constant ratio between incorporation and mass of nucleotide, indicating that proportionate synthesis and release of cyclic AMP occurred during stimulation with hCG. The maximum levels of cyclic AMP in tissue and medium were observed after incubation for 2 hr, with a drop at the fourth hr. The extent of the cyclic AMP response to hCG increased with gonadotropin dose over the range 1–500 ng/ml hCG, with a tendency to fall at extremely high hCG levels. As little as 1 ng/ml hCG produced detectable release of cyclic AMP into the incubation medium; at this and higher hCG doses, testosterone release was maximal and remained constant despite increasing cyclic AMP production and release with high levels of hCG. The release of cyclic AMP during hCG st...
TL;DR: The results suggest that 5 a reduction does not play a role in the action of androgens on the brain structures related to the expression of sexual behavior in the male rat, and that the stereochemical characteristics of the androgen molecule required to elicit sexual behavior are different from those involved in androgenicity.
TL;DR: The lability of the interstitial cells to physical dispersion is reflected in the corresponding loss of hormone-sensitive adenylate cyclase activity during homogenization of the adult rat testis, and may reflect the presence of an inhibitory factor released during physical separation of the testis.
Abstract: Gonadal receptor sites for LH and hCG were originally demonstrated by morphological studies which employed a variety of labeled hormone preparations to show trophic hormone localization in cells concerned with steroid synthesis and secretion (1–4). Uptake of LH by the Leydig cells of the rat testis has been demonstrated in vivo (3), and in vitro with dispersions and cultures of the interstitial cell fraction of the testis (5,6). Interstitial cell dispersions prepared by teasing apart the testis tubules (7) retain the capacity for trophic hormone binding (6) and testosterone biosynthesis from labeled precursors (7,8), but show diminished quantitative responses to LH and hCG in terms of cyclic AMP (9) and testosterone production (10). The lability of the interstitial cells to physical dispersion is reflected in the corresponding loss of hormone-sensitive adenylate cyclase activity during homogenization of the adult rat testis (10), and may reflect the presence of an inhibitory factor released during physical separation of the testis. In contrast, Leydig cells prepared by collagenase digestion of the rat testis display relatively high sensitivity to hCG stimulation in vitro.
TL;DR: A specific androgen-binding protein with high affinity for dihydrotestosterone (DHT) and testosterone (T) is demonstrated in rete testis and efferent duct fluid from the rat testis.
Abstract: Testicular fluid obtained from the rete testis and vasa efferentia has been reported to contain testosterone in concentrations approaching the amount in spermatic venous blood (Voglmayr, Waites & Setchell, 1966; White & Hudson, 1968). Flow rates, which have been established in several mammalian species (Setchell, 1970; Tuck, Setchell, Waites & Young, 1970) would indicate that the exocrine secretion may deliver a substantial quantity of androgen to the caput epididymidis. Testosterone and possibly other androgens in rete testis fluid might also exert a direct influence on spermatozoa as they are transported in this fluid. In the present report, a specific androgen-binding protein with high affinity for dihydrotestosterone (DHT) and testosterone (T) is demonstrated in rete testis and efferent duct fluid from the rat testis. Fluid was collected after ligation of the vasa efferentia for 18 to 20 hr or for 3 days. The 18to 20-hr ligations were made as close to the capsule of the testis as possible and rete testis fluid was collected from anaesthetized rats as described by Setchell& Waites (1971). The 3-day ligations were placed mid-way between testis and caput epididymidis. Animals were decapitated and the efferent ducts were dissected free of blood vessels before collection of fluid by opening the distended ducts. Spermatozoa were removed by centrifugation and the fluid was stored at -20° C. Both methods yielded 0-2 to 0-4 ml fluid/testis. Total protein concentrations were measured by the method of Lowry, Rosebrough, Farr & Randall (1951), using a bovine serum albumin standard. Values of the means and individual standard deviations were 2-4 + 0-6 mg/ml in several samples of rete testis fluid collected 18 to 20 hr after ligation and 8-4+0-4 mg/ml in efferent duct fluid collected 3 days after ligation. Testicular fluid was diluted in 0-01 M-tris-HCl buffer, pH 7-5, containing 0-0015 M-EDTA, 0-002 M-2-mercaptoethanol, 10% glycerol and 0-5% bovine albumin (TEMGA-buffer). Aliquots of diluted fluid were equilibrated at 0° C for 2 hr with tritium-labelled steroids. Proteins were fractionated by polyacrylamide gel electrophoresis (PAGE) and the radioactivity measured in 2-4-mm slices as described by Ritzen, Nayfeh, French & Dobbins (1971). Text-figure 1 shows the single peak of bound [l,2-3H]dihydrotestosterone
TL;DR: It is concluded that an ordered, sequential maturation of the hypothalamic → pituitary gonadotropin → gonadal axis presages the onset of puberty in man.
Abstract: Following the acute intravenous injection of synthetic luteinizing hormone-releasing factor (LRF), plasma testosterone rises to peak levels by 4 hr and increases significantly (p = .02) in adult and pubertal males but not in prepubertal males. The mean maximal increase above basal testosterone levels ±sem in ng/100 ml was 132 ± 31 in 10 adult males, 52 ± 13 in 18 pubertal males, and 0.9 ± 2 in 8 prepubertal males. There was a positive correlation (p pubertal males > prepubertal males. We conclude that an ordered, sequential maturation of the hypothalamic → pituitary gonadotropin → gonadal axis presages the onset of puberty in man.
TL;DR: Results indicate that DHT is capable of maintaining spermatogenesis in the hypophysectomized rat and that testes containing DHT or testosterone implants were heavier than contralateral control testes or gonads implanted with empty silastic capsules.
Abstract: Silastic capsules containing testosterone or dihydrotestosterone (DHT) were implanted into the left testis of adult hypophysectomized rats and the animals were autopsied at the interval of 1, 2, 4, and 8 weeks. At 4 and 8 weeks, testes containing DHT or testosterone implants were heavier than contralateral control testes or gonads implanted with empty silastic capsules. Advanced stages of spermatogenesis were observed adjacent to implants containing testosterone or DHT at 4 or 8 weeks, but were absent in the contralateral testes or testes implanted with empty capsules. These results indicate that DHT is capable of maintaining spermatogenesis in the hypophysectomized rat.
TL;DR: In vitro incubation of tissue homogenates from the hypothalamus and limbic system of adult male and female rabbits with A4 androstene- 3-17-dione-7-3H resulted in the formation of tritium-labeled estrone, with a significant sex difference in hypothalamic activity.
Abstract: In vitro incubation of tissue homogenates from the hypothalamus and limbic system of adult male and female rabbits with A4 androstene- 3-17-dione-7-3H resulted in the formation of tritium-labeled estrone. There was no measurable conversion by the pituitary gland, olfactory lobes and cerebral cortex. Activity was primarily localized in the anterior hypothalamus. While in female rabbits the amount of limbic activity was equal to that in the hypothalamus, in males the hypothalamus was more active than the limbic system. Addition of large amounts of nonradioactive estrone to the incubation had no dramatic or consistent effect on aromatization. There was a significant sex difference in hypothalamic activity; the male being three times as active as the female (p > 0.02). The aromatizing activity in male limbic system was consistently higher than in the female. The sex difference in the hypothalamus was diminished by chronic castration as a result of a markedly increased activity in both sexes. The limbic system...