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PubMed1998

Effects of methanol extract of Chansu on hypothalamic-pituitary-testis function in rats.

Chansu, a galenical preparation of the dried white venom of Chinese Bufo bufo gargarizans, is one of the major components of Kyushin, a traditional Chinese medicine. Kyushin is reported to have a cardiotonic effect that has been suggested to be due to the action of bufadienolides such as bufalin and cinobufagin. Recently, we found that administration of bufalin in male rats diminished the luteinizing hormone (LH) response to gonadotropin-releasing hormone (GnRH) and the secretion of testosterone both in vivo and in vitro. These observations suggest that Chansu may possess hypogonadal effects in male rats. In the present study, the effects of the methanol extract of Chansu on hypothalamic-pituitary-testicular function in male rats were examined. Crude Chansu was extracted by methanol and purified by a Sep-Pak C18 column. No activity of bufalin, cinobufagin, estradiol, or digoxin in purified methanol extract was detected; all Chansu used in this study was the purified methanol extract. A single intravenous injection of Chansu resulted in a decrease of the basal (20% to 55%) and human chorionic gonadotropin (hCG)-induced (35% to 40%) levels of plasma testosterone and the GnRH-induced level of plasma LH (25% to 30%). Administration of Chansu in vitro decreased basal and hCG-stimulated testosterone production by 60% to 70% and 40% to 60%, respectively, as well as spontaneous and forskolin- or 3-isobutyl-1-methylxanthine (IBMX)-induced accumulation of adenosine 3',5'-cyclic monophosphate (cAMP) by 30% to 45% in rat testicular interstitial cells. Although LH release by rat anterior pituitary glands was diminished, GnRH release by the rat mediobasal hypothalamus was enhanced by administration of Chansu in vitro. These results suggest that the bufalin-free extracts of Chansu inhibit testosterone secretion in rats, in part, due to (1) a decreased production of testicular cAMP, (2) a decreased response of testosterone to gonadotropin, and (3) a reduction of the LH response to GnRH.

Animals↗
PubMedDate not supplied

[Effect of human chorionic gonadotropin on the endocrine function of Papio testes].

Radioimmunoassay was used to study secretion of Papio hamadryas testis under stimulation with human chorionic gonadotropin (hCG). It was discovered that hCG had an acute stimulating effect on testicular secretion of testosterone, androstendione and 17-hydroxyprogesterone. It was demonstrated that repeated stimulation with hCG in the presence of the maximal secretory response of the testis (24 h after the first injection and in the presence of its partial reduction (after 72 h) did not provoke any additional rise of testosterone secretion. Unlike the initial response, repeated stimulation with hCG gave rise to dissociation in the time-course of testosterone and 17-hydroxyprogesterone responses. The data obtained attest to temporary "desensitization" of the testis to repeated stimulation with hCG.

17-alpha-Hydroxyprogesterone↗
PubMed1986

Effects of aging on prostate growth in beagles.

Statistical analysis of 82 variables was completed to determine the effects of aging in the male beagle on prostatic growth and function. The results indicate that prostate weight increased to 4 yr and then reached a plateau. Prostatic secretory function (measured as ejaculate volume) followed a course different than the growth of the gland. Prostatic function increased and reached a peak at 4 yr and then declined abruptly. Therefore, there is a separation of the growth and secretory function of the canine prostate after 4 yr of age. Multiple linear regression analysis was performed to determine the mathematical relationship of these variables in predicting prostate weight and therefore benign prostatic hyperplasia, which is correlated with weight. The testicular secretion of testosterone and aging were paramount factors in predicting prostate weight. There appears to be an increased sensitivity of the prostate to testosterone secretion with advancing age.

Aging↗
PubMed1989

[Peripheral effects of prolactin in reproductive function. I. Male reproductive function].

Prolactin plays a peripheral role in male reproductive function just as it does in female function. Prolactin, through the medium of immunocytochemistry acts on testicular steroidogenesis through prolactin receptors which are sited on the Leydig cells. It alters the number of LH receptors and therefore the sensitivity of the testis to central stimulation and equally interferes with androgen synthesis. In the areas of physiological concentration the principal effect seems to be to stimulate secretion of testosterone by keeping up the number of LH receptors; but when there is acute hyperprolactinaemia, testosterone secretion is lowered or perhaps not changed at all because of a "post-receptor effect", in spite of there being larger numbers of LH receptors. The direct effect of prolactin on spermatogenesis has not yet been worked out and the results that have been obtained are controversial. Prolactin exerts a direct stimulating effect on the growth of prostatic cells working synergistically with testosterone through specific prolactin receptors. It could play a role in certain cancers of the prostate.

Humans↗
PubMed2005

Steroidogenic activities of follicle-stimulating hormone in the ovary of Japanese eel, Anguilla japonica.

To clarify the physiological functions of follicle-stimulating hormone (FSH) during oogenesis in Japanese eel, Anguilla japonica, the steroidogenic activities of recombinant Japanese eel FSH (rjeFSH) were assessed in the eel ovary. Female eel were injected with salmon pituitary homogenate to enhance the ovarian development, and the ovaries at different developmental stages were subjected to steroidogenic bioassay. These ovaries could be classified into three types according to oocyte growth and development of ovarian follicular cells. The type-A ovary possessed poorly developed follicular cells around pre- or early vitellogenic oocytes, and rjeFSH did not induce sex steroid secretion. Testosterone (T) secretion was stimulated by rjeFSH in the type-B ovary with developed theca cells and undeveloped granulosa cells around early to mid-vitellogenic oocytes, whereas estradiol-17beta (E2) secretion was not enhanced. The rjeFSH stimulated both T and E2 secretion in a dose-dependent manner from the type-C ovary with fully developed theca and granulosa cells around mid-vitellogenic oocytes. Salmon GTH fraction (sGTH) and a membrane permeable cAMP analogue, 8-bromo-cAMP (8-Br-cAMP) also enhanced T and E2 secretion from the type-C ovary. Human chorionic gonadotropin (hCG) similarly enhanced T secretion, but failed to stimulate E2 secretion from the type-C ovary, suggesting different effects on steroidogenic activities between eel FSH and hCG in eel ovary. There was a positive correlation between the oocyte diameter and E2 secretion from eel ovaries stimulated by rjeFSH. These results suggest that aromatase activity is accelerated by eel FSH in the granulosa cells, which develop following theca cell development in this species.

Anguilla↗
PubMed1977

Evaluation of methods for perfusing rat testes.

Organ perfusion methods offer a number of advantages in biologic studies but require full characterization before application. Two new methods for perfusing rat testes were characterized and compared with recirculating hemicorpus system. These preparations, selective and isolated testicular perfusion, are nonrecirculating and consequently, allow direct measurement of testosterone secretion. In both systems, testosterone production was a fuction of the dose of human chorionic gonadotropin in the perfusion medium up to 1000 mIU per ml which appeared to be inhibitory. The isolated testis method, in comparison with the selective, is more sensitive to human chorionic gonadotropin, requires less perfusion medium, maintains normal blood flow rates and water content, and is associated with no ischemia at commencement of perfusion. However, this system does not retain normal levels of ATP and GTP after 3 hr of perfusion. Whereas both procedures may be used for studies of testosterone secretion and androgen receptors, the inability to maintain testicular ATP and GTP levels indicates that present methods are not suitable for study of processes dependent upon high energy phosphate metabolism.

Adenosine Triphosphate↗
PubMedDate not supplied

Leydig cell cooperation in vitro: evidence for communication between adult rat Leydig cells.

In short-term incubations (32 C, 3 h) of purified adult rat Leydig cells, increasing the density from 5000 to 50,000 cells/16 mm diameter culture well caused a significant increase in human chorionic gonadotropin (hCG)-stimulated testosterone secretion/cell. Density-dependent stimulation was also observed under basal conditions and in the presence of dibutyryl cyclic adenosine monophosphate, luteinizing hormone-releasing hormone, or 22-hydroxy cholesterol. In contrast, increasing the incubation density of purified Leydig cells by addition of other testicular cells had no effect on basal or hCG-stimulated testosterone secretion. hCG-stimulated testosterone secretion by Leydig cells incubated at low density was also increased by addition of Leydig cell-conditioned medium. This stimulatory activity was removed by charcoal extraction and by ultrafiltration (approximately 30 kDa cut-off). The data indicate that Leydig cells cooperate by secretion of low molecular weight, cell-specific stimulatory factors that support Leydig cell steroidogenesis in vitro, and may also play a role in regulating Leydig cell function in vivo.

Animals↗
PubMedDate not supplied

The actions of calcitonin on the TM3 Leydig cell line and on rat Leydig cell-enriched cultures.

Studies demonstrating calcitonin receptors on Leydig cells have suggested that these cells may be one of the many sites affected by this peptide. To investigate this possibility, the effect of synthetic salmon calcitonin on the TM3 Leydig cell line (derived from immature mouse Leydig cells) and on primary Leydig cell-enriched preparations was examined. Synthetic salmon calcitonin stimulated the conversion of [3H]adenine to [3H]cyclic AMP in TM3 cells. In addition, the hormone stimulated the basal secretion of testosterone in both TM3 cell- and Leydig cell-enriched cultures and potentiated the action of hCG on Leydig cell-enriched cultures. Synthetic salmon calcitonin also increased the concentration of androgen and estrogen receptors in cultured TM3 Leydig cells by 2- and 4-fold, respectively, when added to the culture medium (1 micrograms/ml). The fact that 8-bromo-cyclic AMP decreased both androgen and estrogen receptor concentrations suggested that the effect of calcitonin on sex steroid receptors is not mediated by its effect on cyclic AMP in these cells. The possibility that the action of calcitonin on steroid receptors might be mediated by another messenger such as calcium (Ca2+) was therefore considered. Progressively lowering the concentration of Ca2+ in the culture medium of the cells from 1.5 mM to less than 0.01 mM decreased the concentration of both androgen and estrogen receptors. Returning the Ca2+ concentration to normal levels (1.5 mM) restored steroid receptor levels. Receptor levels were also decreased when the extracellular Ca2+ concentration was lowered to 0.5 mM, and treatment with the Ca2+ ionophore, A23187 (1 microM), restored receptor levels to normal. The calcium channel blocker, verapamil, decreased the androgen receptor concentration but unexpectedly increased the concentration of estrogen receptors. It was concluded that calcitonin stimulates cAMP formation and testosterone secretion, and increases the concentration of sex steroid receptors. These observations provide evidence that the previously demonstrated calcitonin receptors on Leydig cells may be coupled to several biologic responses in this cell type.

Animals↗
PubMed1995

Testicular steroid biosynthesis in a boy with a large cell calcifying Sertoli cell tumor producing prepubertal gynecomastia.

A study of a large cell calcifying Sertoli cell tumor of the testis associated with bilateral gynecomastia in an 8-year-old boy is presented. Macroscopically, the two testes showed multiple, large, and hard calcified nodules. Histology revealed clusters or cords of tumor cells with foci of calcifications as well as evidences, in the adjacent testicular parenchyma, of initiation of gonadal development, such as early signs of spermatogenesis and sparse Leydig cell differentiation. In vivo, serum hormone studies showed gonadotropin-independent gonadal activity. After orchidectomy two macroscopically distinct fractions of the removed testes, tumoral and extratumoral, were processed separately for cell isolation and culture. The secretion of testosterone, androstenedione, and 17-hydroxyprogesterone to the medium on day 6 of culture showed that steroidogenesis in cells of the extratumoral fraction was more active than in the tumoral fraction. On the other hand, tumoral fraction cells showed much higher aromatase activity than extratumoral cells. Furthermore, conditioned medium of tumoral fraction cells was able to stimulate testosterone secretion when it was added to subcultures of testicular cells isolated from a control subject. It is postulated that tumoral cells might have stimulated neighboring interstitial cells to differentiate into Leydig cells and to secrete androgens, which in turn might have been aromatized to estrogens by tumoral cells.

Adult↗
PubMedDate not supplied

LH/hCG receptors and stimulation of testosterone biosynthesis in the rat testis: changes during foetal development in vivo and in vitro.

The development of gonadotropin receptors to LH/hCG in the foetal rat testis from 14 to 20 days of gestation was monitored by quantitative binding assays using [125I]hCG and compared to testosterone secretion under basal and stimulated conditions in vitro. Specific hCG binding was first detected on day 15. Thereafter the binding increased gradually with advancement in gestational age and correlated with LH-stimulated secretion of testosterone in vitro. On day 18 of gestation the KA was 0.82 x 10(10) M-1 and the binding capacity was 0.57 fmoles per testis. No binding was detectable in the female gonads at this age. The differentiation of hCG receptors obtained in vitro was very low, although it was sufficient to give a full response to LH with testosterone biosynthesis. The results of the present study suggest that functional receptors do not appear before the capacity to synthesize testosterone is expressed and that their appearance is not dependent on factors extrinsic to the testis. However, additional factors could be necessary for a full development of the receptors.

Animals↗
PubMedDate not supplied

[Why aren't Leydig cell tumors of the ovary diagnosed in time?].

INTRODUCTION: Leydig cell tumor is a rare sex-cord tumor with sex steroid secretion (mostly testosterone). All clinical symptoms and signs are the consequence of extremely high testosterone level. The diagnosis is confirmed using hormone analysis. CASE DESCRIPTION: A 46-year-old woman with previously normal reproductive function was admitted to the hospital due to hirsutism, temporal hair loss, hoarse voice, increased libido, amenorrhea and clitoromegaly. The examination revealed hirsutism score 36 and signs of defeminization and virilisation. Basal testosterone levels were extremely high before operation, while follicle stimulating hormone and luteinizing hormone were suppressed. Androstenedione was above normal level, while other hormones were normal. Testosterone increased twice in response to Pregnyl. In regard to dexamethasone test there was no response of testosterone, indicating a virilizing ovary tumor. The ultrasound of pelvis was normal. Intraoperatively, a solid 2.3 cm Leydig cell tumor was diagnosed. Testosterone decreased promptly. CONCLUSION: This study points to a long-term diagnostic procedure in Leydig cell tumor detection and effects of endogenous testosterone secretion on hypothalamic-pituitary-ovarian axis.

Female↗
PubMed2003

Middle-aged men secrete less testosterone at night than young healthy men.

Aging men largely maintain their testicular androgen production. Cross-sectional studies have demonstrated that after the age of 40 yr a 0.2-2% annual decline is observed in morning total testosterone. In elderly males, the coordinate release of LH and testosterone became asynchronous despite normal serum levels of these hormones. The aim of this study was to test the reproductive hormone rhythm at night in middle-aged men. We studied seven healthy middle-aged (46.6 +/- 6.7 yr) and six healthy young (23.9 +/- 2.4 yr) men by determining their serum levels of LH and testosterone levels every 15 min from 1900-0700 h with simultaneous sleep recordings. The nocturnal rise in testosterone occurred earlier in young men (2235 +/- 0022 h) and at 2331 +/- 0057 h in middle-aged men (P < 0.04). In young men, the mean testosterone level at night (5.0 +/- 1.3 ng/ml; 17.4 +/- 4.4 nmol/liter) and the integrated nocturnal secretion [area under the curve (AUC); 60.6 +/- 8.9 ng/ml.h; 210 +/- 31 nmol/liter.h] were significantly higher compared with the values (3.6 +/- 1.1 and 31.1 +/- 7.2 ng/ml.h; 12.6 +/- 3.8 and 108 +/- 24.8 nmol/liter.h, respectively) observed in middle-aged men (P < 0.04 and P < 0.01, respectively). The mean (3.5 +/- 0.3 mIU/ml; 3.5 +/- 0.3 IU/liter) and AUC (43.4 +/- 8.3 mIU/ml.h; 43.4 +/- 8.3 IU/liter.h) LH values in middle-aged men were significantly higher than the values observed in young men (2.0 +/- 0.7 and 30.8 +/- 6.1 mIU/ml.h; 2.0 +/- 0.7 and 30.8 +/- 6.1 IU/liter.h; P < 0.05 and P < 0.01, respectively). Young men had significantly more testosterone pulses at night (6.7 +/- 1.6/12 vs. 3.8 +/- 1.1/12 h in middle-aged men; P < 0.005) of shorter interpulse interval (88.5 +/- 23.6 vs. 137.4 +/- 46.4 min; P < 0.02). LH pulse characteristics and sleep quality were similar in both groups. However, the first rapid eye movement (REM) sleep episode occurred earlier in middle-aged men (2303 +/- 0034 h) vs. young men (0010 +/- 0054 h; P < 0.04). As a consequence, the testosterone rise antedated the first REM episode by 90 min in young men. The link between testosterone rise and REM sleep episode was not observed in middle-aged men. Linear regression analysis revealed that the LH AUC was significantly related to age (P < 0.02). Analysis of covariance revealed that the two groups differed significantly in testosterone AUC (P < 0.04). Comparison of LH and testosterone concentrations showed significant and positive cross-correlations between LH and testosterone only in young men, with the testosterone rise lagging 60 min after the rise in LH. Our findings suggest that in middle-aged men, less pulsatile testosterone and more LH are secreted at night than in young men, with disruption of the association between testosterone rhythm and REM sleep. The decline in nocturnal testosterone secretion appears to involve a combination of testicular and pituitary hypogonadism.

Adult↗
PubMed1997

Pituitary adenylate cyclase activating polypeptide stimulates rat Leydig cell steroidogenesis through a novel transduction pathway.

The aim of the present study was to evaluate the effects of pituitary adenylate cyclase activating polypeptide (PACAP) on testosterone production in isolated adult rat Leydig cells and its possible mechanisms of action. PACAP-38 stimulated testosterone secretion in a dose-dependent manner with a minimal and a maximal efficacious dose of 1.0 nM and 100 nM, respectively. PACAP-27 was without effect on testosterone secretion at any dose tested. Similarly, vasoactive intestinal peptide did not stimulate steroidogenesis nor interfere with PACAP-38 activity, as well as preincubation of Leydig cells with the vasoactive intestinal peptide-antagonist [Lys(1), Pro(2,5), Arg(3,4), Tyr(6)]-vasoactive intestinal peptide. Removal of extracellular Ca2+ did not inhibit the stimulatory effects of PACAP-38 on Leydig cell testosterone production. Neither PACAP-38 nor PACAP-27 modified intracellular free Ca2+ and cAMP levels at any dose tested thus excluding a role for Ca2+ and cAMP in the stimulatory effects of PACAP. PACAP-38 was able to induce a plasma membrane depolarization that was dependent on an influx of Na+ from the extracellular medium as confirmed by the monitoring of intracellular Na+ with the Na+-sensitive fluorescent dye sodium benzofuran isophtalate. When Na+ was removed from the extracellular medium, PACAP-38 did not stimulate testosterone production, demonstrating that Na+ influx through the plasma membrane is strictly related to the stimulatory effects of this peptide. In addition, preincubation of Leydig cells in the presence of pertussis-toxin (500 ng/ml for 5 h) significantly reduced PACAP-38-stimulated effects both on plasma membrane depolarization and testosterone secretion. These results demonstrate that PACAP-38 stimulates testosterone secretion in isolated adult rat Leydig cells through the interaction with a novel PACAP receptor subtype coupled to a pertussis toxin sensitive G protein whose activation induces a Na+-dependent depolarization of the plasma membrane and testosterone production.

Adenylate Cyclase Toxin↗
PubMed2006

Use of a GnRH agonist and hCG to obtain an index of testosterone secretory capacity in the koala (Phascolarctos cinereus).

Testosterone secretion in mammals typically occurs in random pulses such that a single blood sample provides limited information on reproductive endocrine status. However, it has been shown in several species that an index of the prevailing testosterone biosynthetic capacity of the testes can be obtained by measuring the increase in circulating testosterone after injection of a GnRH agonist or human chorionic gonadotrophin (hCG). Hence, the aims of the present study were to examine fluctuations in testosterone secretion in the koala (n = 6) over a 24-hour period and then characterise testosterone secretion after injection of the GnRH agonist buserelin (4 micro g) or hCG (1000 IU). The latter was used to establish an index of the prevailing testosterone biosynthetic capacity of the koala testis. Individual koalas showed major changes in blood testosterone concentrations over 24 hours, but there was no apparent diurnal pattern of testosterone secretion (P > .05). Injection of buserelin and hCG resulted in an increase (P < .05) in blood testosterone concentration. After injection of exogenous hormone, near maximal concentrations of testosterone occurred at around 60 minutes. There was a tendency for plasma testosterone to decline after 90 minutes with buserelin, but concentrations remained close to the upper limit for 240 minutes with hCG. There were strong positive correlations between the average testosterone concentration over 24 hours and the maximum observed testosterone concentration after stimulation with GnRH and hCG (GnRH, r = .772; P = .07 and hCG, r = 1.0; P < .01). The findings in the present study confirmed that individual male koalas can show large fluctuations in blood testosterone concentrations over time and that a GnRH agonist and hCG can be used in the koala to obtain an index of the prevailing steroidogenic capacity of the testes.

Animals↗
PubMed2000

In vitro pituitary and testicular effects of the leptin-related synthetic peptide leptin(116-130) amide involve actions both similar to and distinct from those of the native leptin molecule in the adult rat.

The obese gene (ob) product, leptin, has recently emerged as a key element in body weight homeostasis, neuroendocrine function and fertility. Identification of biologically active, readily synthesized fragments of the leptin molecule has drawn considerable attention, as they may provide a powerful tool for detailed characterization of the biological actions of leptin in different experimental settings. Recently, a fragment of mouse leptin protein comprising amino acids 116-130, termed leptin(116-130) amide, was shown to mimic the effects of the native molecule in terms of body weight gain and food intake, and to elicit LH and prolactin (PRL) secretion in vivo. As a continuation of our previous experimental work, the present study reports on the effects of leptin(116-130) amide on basal and stimulated testosterone secretion by adult rat testis in vitro. In addition, a comparison of the effects of human recombinant leptin and leptin(116-130) amide at the pituitary level on the patterns of LH, FSH, PRL and GH secretion is presented. As reported previously by our group, human recombinant leptin(10(-9)-10(-7)M) significantly inhibited both basal and human chorionic gonadotrophin (hCG)-stimulated testosterone secretion in vitro. Similarly, incubation of testicular tissue in the presence of increasing concentrations of leptin(116-130) amide (10(-9)-10(-5)M) resulted in a dose-dependent inhibition of basal and hCG-stimulated testosterone secretion; a reduction that was significant from a dose of 10(-7)M upwards. In addition, leptin(116-130) amide, at all doses tested (10(-9)-10(-5)M), significantly decreased LH and FSH secretion by incubated hemi-pituitaries from adult male rats. In contrast, in the same experimental protocol, recombinant leptin(10(-9)-10(-7)M) was ineffective in modulating LH and FSH release. Finally, neither recombinant leptin nor leptin(116-130) amide were able to change basal PRL and GH secretion in vitro. Our results confirm the ability of leptin, acting at the testicular level, to inhibit testosterone secretion, and map the effect to a domain of the leptin molecule that lies between amino acid residues 116 and 130. In addition, we provide evidence for a direct inhibitory action of leptin(116-130) amide on pituitary LH and FSH secretion, a phenomenon not observed for the native leptin molecule, in the adult male rat.

Animals↗
PubMed1981

Cryptorchidism and the pituitary--testicular axis in bulls.

In calves made cryptorchid at birth, serum LH concentrations were elevated (P less than 0.01) over those of intact controls by 7 weeks of age; a difference which persisted until after puberty. When intact and cryptorchid bulls were given LH-RH, i.v., at approximately 18 months of age, cryptorchid bulls were more responsive. Serum LH concentrations (mean +/- s.e.m.) after 250, 1000 and 4000 ng LH-RH were 0.2 +/- 0.03, 1.2 +/- 0.3 and 12.1 +/- 2.0 ng/ml for intact bulls and 1.0 +/- 0.6, 5.1 +/- 0.8 and 19.6 +/- 2.1 ng/ml for cryptorchid bulls. Testes from cryptorchid bulls weighed less (P less than 0.01) than testes from intact bulls (68 +/- 6 and 655 +/- 36 g) at 24 months of age. Ability to secrete testosterone in vitro was determined by incubating minced pieces of testes at 36 degrees C for 3 h in Krebs-Ringer-bicarbonate buffer (pH 7.2) containing 1 mg glucose/ml and 100 mi.u. hCG/ml. Cryptorchid testes secreted slightly more testosterone than scrotal testes on a unit weight basis, but when expressed on a paired testis weight basis, testosterone secretion by cryptorchid testes was less (8 +/- 2 and 60 +/- 10 mg, P less than 0.01). Autoradiographic localization techniques were used to show the existence of LH/hCG binding sites in cryptorchid testes. These studies suggest that cryptorchid bull testes have a reduced capacity to secrete testosterone and the near-normal serum testosterone concentrations are maintained in the presence of increased serum gonadotrophins.

Aging↗
PubMed1992

Modulation of pituitary gonadotropins and prolactin secretion by testosterone in vitro.

Investigations were undertaken to study the differential modulation of LH, FSH and PRL secretion by testosterone (T) using whole pituitary (PI) or pituitary-hypothalamus coincubates (PHC) as in vitro constructs. PI and PHC from intact and castrated rats were incubated with or without T thrice, for 24 h each, (24 h x 3, total incubation period 72 h). The spent media was replenished every 24 h. At the end of 72 h, a few of the pituitary glands were challenged with 10 nM LHRH for 4 h. The spent media and pituitary glands were analyzed for LH, FSH and PRL using specific RIAs. Incubation of PI or PHC from intact rats with T stimulated the release of LH and FSH but inhibited the release of PRL. T had no effect on the intrapituitary contents of LH but inhibited intrapituitary contents of FSH and PRL, as compared to controls incubated without T. Castration increased intrapituitary contents of LH and FSH with concomitant decrease in PRL levels. Incubation of PI or PHC from castrated rats with T inhibited intrapituitary contents of LH to intact pituitary levels, while PRL levels were further reduced instead of being ameliorated. It is concluded that PI or PHC can be used as convenient in vitro models to monitor the effect of castration or of T modulation of pituitary and hypothalamus functions. T does not affect the synthesis of LH at the gonadotroph level but facilitates the regulation of intracellular LH and FSH levels. It is postulated that T inhibits the synthesis of FSH/PRL at the gonadotroph/lactotroph levels.

Animals↗
PubMed1986

[Isolated secretion of testosterone by an adrenocortical tumor in a menopausal woman].

A case of adrenal tumor with isolated secretion of testosterone in a menopaused woman is reported. All other androgens (Déhydro-épi-androstérone, Sulfate de Déhydro-épi-androstérone, Delta 4 androstène-dione) were normal as well as other adrenal hormones. This tumor produced a mild hirsutism. A treatment with Cyproterone Acetate, then with Dexamethasone did not produce a significant change. A complete review of literature points out the rarity of this observation, since only twelve similar cases have been previously reported.

Adenoma↗