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PubMed1999

Development and differentiation of the interstitial and tubular compartments of fetal porcine testes.

Male differentiation is initiated by fetal testicular androgen synthesis, catalyzed by the enzyme 17alpha-hydroxylase/17,20 lyase cytochrome P450 (P450c17). This study was an investigation of testicular development and differentiation in porcine fetuses recovered on Days 30-42 of gestation. The expression of P450c17 was localized in fetal gonads by in situ hybridization and immunocytochemistry and related to cellular proliferation through expression of the proliferating cell nuclear antigen (PCNA). Gonadal P450c17 expression was quantified by Western immunoblot analysis and related to testosterone secretion by cultured explants of fetal gonads. P450c17 transcripts were detected in the interstitium surrounding testicular cords preceding the appearance of the enzyme protein. The intensity of both P450c17 hybridization and staining was greater in Yorkshire fetal gonads, which also exhibited more advanced tubular development. PCNA staining was prominent within tubular primordia and was higher in testes from Yorkshire than from Meishan fetuses on all days examined. P450c17 expression paralleled testosterone secretion, which decreased by Day 42, and was generally less in cultures of Meishan than of Yorkshire fetal gonads. These data demonstrate that the expression of P450c17 in porcine fetal testes coincides with differentiation of central medullary cells and androgen secretion during gonadal development between Days 30 and 42 of gestation. This occurs as medullary cords organize and is associated with changes in cellular proliferation within the tubular compartment.

Animals↗
PubMed1989

Diagnosis and resection of an oral contraceptive-suppressible Sertoli-Leydig cell tumor with preservation of fertility and a 7-year follow-up.

A 21-year-old white woman presented with virilization, hirsutism, and acne of 1.5 years' duration. Endocrine testing demonstrated complete suppression of serum testosterone, from 5.3 to 0.6 ng/mL, and serum androstenedione, from 4.7 to 1.7 ng/mL, after oral administration of 50 micrograms of mestranol and 1 mg of norethindrone for 21 days. No suppression of either steroid was produced by dexamethasone, whereas serum dehydroepiandrosterone sulfate was suppressed from 5.2 to 1.9 micrograms/mL. A left salpingo-oophorectomy was performed for a 3 x 4-cm Sertoli-Leydig cell tumor of intermediate differentiation. Intraoperative studies demonstrated that the tumor secreted testosterone, androstenedione, 17 alpha-hydroxyprogesterone, and estradiol, but not dehydroepiandrosterone sulfate. These findings support the thesis that hormonal manipulation tests cannot differentiate between adrenal and ovarian virilizing tumors. Nor does the oral contraceptive suppression of testosterone secretion exclude an ovarian malignancy. The patient remains free of recurrence after 7 years.

Adult↗
PubMed2004

Effects of melatonin treatment on Leydig cell activity in the testis of the frog Rana esculenta.

This study was conducted to verify the effect(s) of melatonin treatment on frog Leydig cells. Morphological observation after melatonin treatment indicates that many frog Leydig cells show degenerative changes (i.e. heterochromatic nuclei, loss of cellular adhesion) while in adjacent germinal tubules several Sertoli cells show heterochromatic nuclei, confirming the presence of a paracrine effect between interstitial and germinal compartments. The effect of melatonin on frog Leydig cell steroidogenesis was investigated in in vitro experiments; after 6 h of incubation melatonin severely inhibits both control and GnRH-induced testosterone secretion. In addition, in order to verify the effect of indolamine on frog Leydig cell activity, we investigated, by in situ hybridization, the presence of frog relaxin (fRLX, a transcript specifically expressed by these cells) in the testes of melatonin-injected animals after 48 h. fRLX signal completely disappeared from the testis of melatonin- injected frogs. The results of the present study indicate that melatonin treatment provokes Leydig cell morphological changes, blocks GnRH-antagonist-induced testosterone secretion and decreases fRLX expression. Taken together these results strongly indicate that melatonin acts on Leydig cells in the testis of the frog Rana esculenta.

Analysis of Variance↗
PubMed2000

Identification of the lipophilic factor produced by macrophages that stimulates steroidogenesis.

Macrophages are known to release a lipophilic factor that stimulates testosterone production by Leydig cells. This macrophage-derived factor (MDF) is thought to be physiologically relevant, because removal of macrophages from the testis results in altered testosterone secretion and reduced fertility. The purpose of the present study was to purify this factor, elucidate its chemical structure, and determine whether it is both present in the testis and acts when injected intratesticularly. Culture media from testicular and peritoneal macrophages were extracted with ether, and the organic phase was sequentially purified on C18, silica, and cyano-HPLC columns. MDF was detected using a rat Leydig cell bioassay, with testosterone secretion being the end point. Purified material and crude ether extracts were analyzed by gas chromatography/mass spectrometry and nuclear magnetic resonance spectroscopy. The time of elution of MDF from both testicular and peritoneal macrophages was identical on all three HPLC columns. A single peak was observed when MDF, obtained from the final HPLC column, was analyzed by gas chromatography. The MS fragmentation pattern of purified material from both peritoneal and testicular macrophages was identical to that of a reference preparation of 25-hydroxycholesterol. Also, the nuclear magnetic resonance spectrum of MDF was similar to that of authentic 25-hydroxycholesterol. When 25-hydroxycholesterol was subjected to the identical purification scheme as MDF, it was found to elute at the same times as MDF on all three columns and elicited activity in the Leydig cell bioassay as expected. Control medium purified identically did not contain 25-hydroxycholesterol or have biological activity. Ether extracts of testis contained 25-hydroxycholesterol, indicating that this compound is present under physiological conditions. Similarly, when 25-hydroxycholesterol was injected into the testis of adult rats, testosterone production was increased within 3 h. Taken together, these data indicate that the lipophilic factor produced by macrophages that stimulates steroidogenesis is 25-hydroxycholesterol.

Animals↗
PubMed1993

LH pulsatile secretion and testosterone blood levels are influenced by sexual arousal in human males.

To determine whether changes in LH and testosterone (T) blood levels and pulse signals were induced by sexual arousal, nine healthy young males were presented on two different days with a sexually arousing (S) and a sexually neutral control (C) film. On both sessions, blood was sampled every 10 min for 12 hr. The Cluster and the Detect pulse identification algorithms were used to characterize the peaks in LH and T series. The second plasma LH peak following the beginning of the film was higher in the S than in the C condition (percent increases above preceding nadir: 322.1 +/- 183.9% vs. 202.6 +/- 108.7%). The area of the second pituitary peak of LH instantaneous secretion rate, which corresponded to the second plasma LH peak, was also greater in the S condition (6.2 +/- 3.3 vs. 3.4 +/- 2.3 UI/l). Compared with the C condition, T blood levels were increased within the first 10 min of sexual arousal (25.2 +/- 6.3 vs. 22.2 +/- 5.6 nmol/l). These results, consistent with the findings of animal studies, indicate that LH pulsatile secretion and T blood levels are influenced by changes in the state of sexual arousal in human males.

Adult↗
PubMed2001

LH secretion and testosterone concentrations are blunted after resistance exercise in men.

This study examined the hypothesis that exercise-induced changes in circulating testosterone would be centrally mediated via hypothalamic-pituitary release of luteinizing hormone (LH). We tested this hypothesis by examining overnight LH, total and free testosterone (TT and FT), and cortisol (C) concentrations in 10 young healthy men (21 +/- 1 yr) during two experimental sessions: a control and an acute heavy-resistance exercise bout (50 total sets consisting of squats, bench press, leg press, and latissimus dorsi pull-down). Exercise was performed from 1500 to 1700, and blood sampling began at 1700 and continued until 0600 the next morning. Blood was sampled every 10 min for LH and every hour for TT, FT, and C. Hormonal concentrations were determined via RIA, and the secretion characteristics of LH were analyzed with deconvolution analysis. When overnight postexercise concentrations were compared with control concentrations, no statistically significant (P < or = 0.05) differences were observed for LH half-life, LH pulse frequency, interpulse interval, pulse amplitude, or pulse mass. Significant differences were observed for LH production rate (13.6 +/- 4 and 17.9 +/- 5 IU. l distribution volume(-1) x day(-1) for exercise and control, respectively, a 24% reduction). For the ANOVA marginal main effect means due to condition, C was significantly elevated (5.9 +/- 0.7 vs. 4.0 +/- 0.4 microg/dl), while TT (464 +/- 23 vs. 529 +/- 32 ng/dl) and FT (15.6 +/- 0.7 vs. 18.3 +/- 0.9 pg/ml) were significantly decreased for the exercise condition. These data demonstrate that the decline in overnight testosterone concentrations after acute heavy-resistance exercise is accompanied by a blunted LH production rate and elevated C concentrations.

Adult↗
PubMed1985

Implantation of normal fetal preoptic area into hypogonadal mutant mice: temporal relationships of the growth of gonadotropin-releasing hormone neurons and the development of the pituitary/testicular axis.

Central nervous system tissue which included the preoptic area (an area rich in gonadotropin-releasing hormone neurons) was taken from normal 17-day fetal mice and transplanted into the infundibular recess of the third ventricle of the hypothalamus of 90-day male mutant hypogonadal mouse hosts that are unable to synthesize the neurohormone, gonadotropin-releasing hormone. The growth and development of gonadotropin-releasing hormone neurons and fibers in the donor and host tissue as well as recovery of the pituitary-testicular axis were followed from 10 to 120 days post-implantation. Testicular growth was evident in 94% of the hypogonadal animals within 30 days post-implantation, continued for 90 days but showed no further increase during the remainder of the experiment. Increases in seminal vesicle weight, an index of testosterone secretion, were measurable at 30 days and continued through to the end of the experiment. Pituitary concentrations of gonadotropins were doubled at 30 days over that seen in the control mutant mouse and were maintained thereafter at normal or supranormal concentrations. In contrast plasma levels of gonadotropins, although above baseline at 30 days, never reached normal circulating levels. Nevertheless, it appeared that the concentration of luteinizing hormone achieved was sufficient to initiate and maintain testicular growth and testosterone secretion for the entire duration of the experiment. Immunocytochemical analysis of brain tissue was used to determine the presence and numbers of gonadotropin-releasing hormone neurons in the transplant and the distribution of their fibers in the donor and host tissue. The numbers of immunoreactive gonadotropin-releasing hormone neurons present at the time of sacrifice ranged from 3 to 140. Fiber outgrowth from the donor cells into the host was noted as early as 10 days post-implantation and the density of outgrowth continued to increase over the course of the experiment. Positive fibers tended to accumulate over the tuberoinfundibular sulci as they do in normal animals. In those instances where the transplant was placed a long distance from the median eminence, the gonadotropin-releasing hormone axons grew on the internal surface of the third ventricle until they reached these specific exit zones. These studies indicate that in the mutant hypogonadal mouse, central nervous system transplants from normal fetal mice can maintain the function of the pituitary-gonadal axis for periods of up to 120 days post-implantation. Outgrowth of the neurosecretory fibers begins very soon after implantation and the axons tend to follow pathways seen in normal tissue.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1991

Evidence that inhibin plays a major role in the regulation of follicle-stimulating hormone secretion in the fully adult male rhesus monkey (Macaca mulatta).

In the juvenile male rhesus monkey in which an adult-like pattern of endocrine activity in the pituitary-testicular axis is imposed by pulsatile stimulation with exogenous GnRH, administration of inhibin antiserum elicits a marked and selective hypersecretion of FSH. This finding suggests that in the monkey, testicular inhibin plays a major role in the postpubertal regulation of this gonadotropin. The purpose of the present study was to confirm this view more directly. To this end, 10 adult male rhesus monkeys were implanted with indwelling venous catheters and housed in specialized cages that permit continuous access to the venous circulation with minimal restraint and without tranquilization. Six of the males received a continuous infusion of an ovine antiserum to the alpha-subunit of human inhibin (iv bolus injection of 2.22 ml/kg BW, followed by a continuous infusion of serum at 0.62 ml/kg BW.24 h), and 4 animals received a similar infusion of control ovine immune serum. The duration of the infusion of the inhibin antiserum ranged from 2.5-7.5 days, and that for the control serum was 7.5 days. The FSH response to immunoneutralization of circulating inhibin was determined by measuring concentrations of this gonadotropin in sequential plasma samples collected between 1900-2300 h on the day before initiation of the anti-serum infusion and, depending on the duration of the infusion, on days 0.5, 1.5, 2.5, 4.5, and 6.5 of antiserum administration. In 5 of the 6 animals that received the inhibin antiserum, a progressive hypersecretion of FSH was observed during the initial 2.5 days of the infusion. This increase in circulating FSH concentration, which reached, by day 2.5 of treatment, a value 2- to 3-fold greater (P less than 0.05) than the pretreatment control level, was not associated with changes in either LH or testosterone levels. Continuation of the infusion of the inhibin antiserum beyond 2.5 days invariably resulted in a marked decline in LH and testosterone secretion, suggesting that the hypophysiotropic drive to the pituitary-testicular axis may have been compromised, presumably by a mechanism related to the infusion of heterologous serum. Infusion of the control immune serum for 2.5 days was not associated with an elevation of circulating FSH concentrations, and changes in circulating concentrations of plasma LH and testosterone were, as expected, unremarkable. Continuation of the infusion of control serum, like that of antiserum, generally resulted in a temporary but precipitous decline in LH and testosterone secretion.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Role of sialic acid residues in the in vitro superactivity of human choriogonadotropin (hCG) in rat Leydig cells.

The binding activity (B) of porcine Luteinizing Hormone (pLH) to rat LH receptor as well as its stimulating activity (S) of testosterone secretion by rat Leydig cells in vitro are similar to those of the homologous hormone rat LH (S/B = 1). By contrast, the human Chorionic Gonadotropin (CG) and hLH exhibit stimulating activities relative to rat LH that are considerably higher than their relative binding activities (S/B > 100) indicating that they have an abnormally high transducing efficiency (superactivity) after receptor binding. The heterologous hybrid alpha pLH x beta hCG is as superactive as native hCG and recombined alpha hCG x beta hCG whereas alpha hCG x beta pLH exhibits no superactivity, like native pLH and alpha pLH x beta pLH demonstrating that hCG superactivity is due to its beta-subunit. The removal of sialic acid residues with neuraminidase dramatically diminished hCG stimulating activity without impairing its receptor binding activity but the S/B ratio for asialo-hCG never reached values lower than 1. Similar treatments had no effect on the S/B ratios of non-superactive gonadotropins, pLH and equine CG. Sialic acid residues in the Asn beta 30 carbohydrate chains of hLH and hCG appear to be responsible for their superactivity in the in vitro stimulation of testosterone secretion by rat Leydig cells.

Animals↗
PubMed2005

Endogenous estrogens inhibit mouse fetal Leydig cell development via estrogen receptor alpha.

It is now accepted that estrogens play a role in male fertility and that exposure to exogenous estrogens during fetal/neonatal life can lead to reproductive disorders in the male. However, the estrogen receptor (ER)-mediated processes involved in the regulation of male reproduction during fetal and neonatal development are still largely unclear. We previously reported that ER beta deficiency affects gametogenesis in mice but changes neither the number nor the differentiated functions of fetal Leydig cells. We show here that ER alpha-deficient mice (ER alpha-/-) display higher levels of testicular testosterone secretion than wild-type mice from fetal d 13.5 onwards. This results from higher levels of steroidogenic activity per fetal Leydig cell, as indicated by the hypertrophy of these cells and the higher levels of mRNA for StAR, P450c17 and P450scc in the testis, for a similar number of Leydig cells. Because LH is not produced on fetal d 13.5 and because no change in plasma LH concentration was observed in 2-d-old ER alpha-deficient mice, LH is probably not involved in the effects of estrogens on testicular steroidogenesis in fetal and early neonatal Leydig cells. Furthermore, inactivation of ER beta did not change the effect of ER alpha inactivation on steroidogenesis. Lastly, in an organ culture system, 1 mum diethylstilbestrol decreased the testosterone secretion of wild-type fetal and neonatal testes but not of ER alpha-/- testes. Thus, this study shows that endogenous estrogens physiologically inhibit steroidogenesis via ER alpha by acting directly on the testis early in fetal and neonatal development.

Animals↗
PubMed2005

Morphometric studies on the testis of Korean ring-necked pheasant (Phasianus colchicus karpowi) during the breeding and non-breeding seasons.

The purpose of this study was to obtain detailed quantitative information on all cell types in the testis interstitium of Korean ring-necked pheasants and to combine these data with changes in the steroidogenic function of the testis during the breeding and non-breeding seasons. For animals collected during the breeding season, their testis weights, sperm production, serum testosterone levels and leuteinizing hormone (LH)-stimulated testosterone secretion were significantly (p < 0.01) increased compared to the non-breeding season. Testes of the pheasants during the non-breeding season displayed a 98% reduction in testis volume that was associated with a decrease in the absolute volume of seminiferous tubules (98% reduction), tubular lumen (100%), interstitium (90%), blood vessels (84%), lymphatic spaces (97%), Leydig cells (79%), mesenchymal cells (51%) and myoid cells (61%) compared to the breeding season. The numbers of Leydig cells, mesenchymal cells and myoid cells per testis in the breeding season were much higher than in the non-breeding season. Although the mean volume of a Leydig cell was 74% lower in the non-breeding season, the mean volumes of myoid and mesenchymal cells remained unchanged. These results demonstrate that there are striking differences in the testicular structure of the Korean ring-necked pheasant during the breeding and non-breeding seasons. Every structural parameter of the Leydig cell was positively correlated with both testosterone serum levels and LH-stimulated testosterone secretion. The correlation of changes in hormonal status with the morphometric alterations of Leydig cells suggests that the Korean-ring necked pheasant may be used as a model to study structure-function relationships in the avian testis.

Animals↗
PubMed2004

Aging alters the functional expression of enzymatic and non-enzymatic anti-oxidant defense systems in testicular rat Leydig cells.

In aged rats, trophic hormone-stimulated testosterone secretion by isolated Leydig cells is greatly reduced. The current studies were initiated to establish a functional link between excess oxidative stress and the age-related decline in steroidogenesis. Highly purified Leydig cell preparations obtained from 5-month (young mature) and 24-month (old) Sprague-Dawley rats were employed to measure and compare levels of lipid peroxidation, non-enzymatic (alpha-tocopherol, ascorbic acid, and reduced/oxidized glutathione) and enzymatic (Cu, Zn-superoxide dismutase, Cu, Zn-SOD; Mn-superoxide dismutase, Mn-SOD; glutathione peroxidase-1, GPX-1, and catalase, CAT) anti-oxidants. The extent of lipid peroxidation (oxidative damage) in isolated membrane fractions was quantified by measuring the content of thiobarbituric acid-reactive substances (TBARS) under basal conditions, or in the presence of non-enzymatic or enzymatic pro-oxidants. Membrane preparations isolated from Leydig cells from old rats exhibited two- to three-fold enhancement of basal TBARS formation. However, aging had no significant effect on TBARS formation in response to either non-enzymatic or enzymatic pro-oxidants. Among the non-enzymatic anti-oxidants, the levels of reduced glutathione were drastically reduced during aging, while levels of alpha-tocopherol and ascorbic acid remained unchanged. Both steady-state mRNA levels and catalytic activities of Cu, Zn-SOD, Mn-SOD, and GPX-1 were also significantly lower in Leydig cells from 24-month-old rats as compared with 5-month-old control rats. In contrast, neither mRNA levels nor enzyme activity of catalase was sensitive to aging. From these data we conclude that aging is accompanied by reduced expression of key enzymatic and non-enzymatic anti-oxidants in Leydig cells leading to excessive oxidative stress and enhanced oxidative damage (lipid peroxidation). It is postulated that such excessive oxidative insult may contribute to the observed age-related decline in testosterone secretion by testicular Leydig cells.

Aging↗
PubMed1993

The in vitro perifused rat ovary: III. Interrelationship of the follicular and stromal compartments on steroid release.

The preovulatory ovary is composed of two primary tissue components, stroma and follicles. To assess the role of these tissue compartments in ovarian steroidogenesis, stromal tissue, follicular tissue, and a mixture of both tissues from pregnant mare serum gonadotropin (PMSG)-treated, prepubertal rats were perifused simultaneously for 8 h. The basal level of estradiol secretion by stromal tissue was lower (24 +/- 3 pg/mg/30 min), than that secreted by follicles (64 +/- 5.6 pg/mg/30 min, n = 6; p < 0.05). On the other hand, the mean basal levels of progesterone and testosterone secreted by stromal tissue (252 +/- 14 pg/mg/30 min and 162 +/- 18 pg/mg/30 min, respectively) were greater than those secreted by follicular tissue (84 +/- 3 pg/mg/30 min and 81 +/- 4 pg/mg/30 min, respectively). When stromal and follicular tissue were combined the secretion of progesterone, testosterone and estradiol was intermediate to that of the separate tissues. Under gonadotropin stimulation (human menopausal gonadotropins plus follicle stimulating hormone), the follicular tissue secreted greater amounts of steroids than did the stromal tissue, or stromal plus follicular tissue. When stromal tissue and follicular tissue were combined, the levels of basal progesterone and testosterone secreted by both tissues were significantly lower than those of stromal tissue alone. However, the reduction in follicular estradiol secretion induced by stromal tissue under basal conditions, was in large part overcome during gonadotropin perifusion. These observations suggest that locally produced factors may play an inhibitory, paracrine role in the regulation of ovarian steroidogenesis.

Animals↗
PubMed1996

Seasonal changes in circulating serum concentration and in vitro testicular secretion of testosterone and androstenedione in the male vespertilionid bat (Scotophilus heathi).

Seasonal changes in the testicular activity were studied in the male Greater Yellow bat, Scotophilus heathi, in Varanasi, India (25 degrees N, 83 degrees E). The seasonal pattern of body weight of male bats was also recorded and compared with circulating androstenedione (A) and testosterone (T) concentration. There was a gradual increase in the body weight of the bat from September onward mainly due to accumulation of adipose tissue. Finally, body weight reached a peak level in November. Two periods of peak testicular weight and serum T concentration but only one peak of serum A concentration were observed. The first peak of T coincided closely with the peak A concentration and increased body weight. The first peak of T occurs several months before the time of mating and ovulation. The second peak of T correlated closely with the period of mating. In vitro study showed seasonal variation of the testicular responsiveness to LH stimulation. In vitro study also showed two peaks in the T but only one peak in the A production by testes in response to LH during different phases. Preliminary study showed that IGF-I but not insulin augmented hCG induced T production by testes in vitro. Our observation of an increase in serum A concentration during the period of overfeeding and weight gain and decline in A during the period of weight loss in S. heathi adds strength to the concept that nutritional status can influence hormonal function. This may be the reason for asynchrony between male and female gametic cycle found among vespertilionid bats.

Androstenedione↗
PubMed1983

Regulation of human fetal testicular secretion of testosterone: low-density lipoprotein-cholesterol and cholesterol synthesized de novo as steroid precursor.

The results of the present investigation support the conclusion that low-density lipoprotein (LDL)-cholesterol facilitates androgen synthesis in human chorionic gonadotropin (hCG)-treated human fetal testicular tissue in vitro. Moreover, the number of LDL receptors and the rate of de novo synthesis of cholesterol are high during the period of active fetal testicular steroidogenesis and fall with advancing gestational age, suggestive of regulation by hCG.

Androstenedione↗
PubMed1984

Environmental and endocrine control of reproduction in the song sparrow, Melospiza melodia. II. Agonistic interactions as environmental information stimulating secretion of testosterone.

A group of eight free-living adult male song sparrows, selected at random, were given subcutaneous implants of testosterone (T) in Silastic tubing. In a separate area, 1 km distant, a second group of eight free-living males were given empty implants as controls. All implants were administered in late March and early April and in the experimental group maintained plasma levels of T at the springtime peak. To test whether prolonged high levels of T maintained aggressive territorial behavior at the springtime maximum, each bird was "challenged" by stimulating a territorial intrusion achieved by playing tape-recorded conspecific songs on their territories. Sparrows with T implants were more aggressive than controls in accordance with other studies showing that T increases frequency and intensity of aggression. Blood samples were collected from all implanted birds, and their untreated neighbors, at intervals throughout the breeding season, and plasma levels of luteinizing hormone (LH) and T were measured. Circulating T levels in males with territories next to control males show declines in T levels in April, increase again in May, and are low during the parental phase in June and July. However, the decline of T in males with territories next to males implanted with T did not occur, and levels remained significantly higher than those of males in the control area. Plasma T levels did decrease in May, however, but rose again in June, and in July were significantly higher than controls. Curiously, plasma levels of luteinizing hormone did not differ between controls and experimentals.

Aggression↗