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PubMed1989

Plasma luteinizing hormone levels in normal and prenatally stressed male and female rat fetuses and their mothers.

Concentrations of luteinizing hormone (LH) were measured in plasma of fetal and neonatal rats obtained from control mothers and from mothers exposed to stress from Days 14 to 21 of gestation. The regimen of stress used is known to be associated with an abnormal ontogenetic pattern of testosterone secretion from the fetal testes. The overall ontogenetic pattern of immunoreactive LH levels in plasma was similar in male and female rats, and was unaffected by stress. In all groups, LH was low from Days 16 to 20 of gestation, and then rose progressively through birth, i.e. Day 23. However, stressing the mother significantly decreased the already low levels of LH between Days 16 and 20, as indicated by a larger percentage of samples from stressed fetuses of both sexes with LH levels below the limit of sensitivity of the assay. Sex differences in both the control and stressed group became evident only after Day 20 of gestation, with plasma concentrations of females exceeding those of males from Day 21 to 23 post-conception.

Analysis of Variance↗
PubMed1994

The 72-kilodalton protein of the male reproductive tract is differentially expressed and developmentally regulated during Wolffian duct differentiation of the fetal mouse.

Differentiation of the mammalian reproductive tract into the male phenotype is dependent on the presence of functional testes secreting testosterone during in utero development. Recently, we identified a protein fraction (72 kDa) from the developing reproductive tract of the fetal male mouse that is able to mimic the effect of testosterone in stabilizing the Wolffian duct in vitro, suggesting a role played by this protein in mediating the effect of testosterone during Wolffian duct differentiation. In the present study, we further evaluated the masculinizing role of this protein by determining the specific appearance of the 72-kDa protein in relation to reproductive tract differentiation. Using Western blot and immunohistochemical analysis, we demonstrate that the protein was expressed specifically in the male reproductive tract and not in male non-reproductive organs, namely, lung, liver, or kidney. Within the male reproductive tract, the Wolffian duct derivatives demonstrated a high level of expression of the protein, whereas the urogenital sinus produced only a low level of reaction to this antibody in Western analysis and no reaction in the histochemical analysis. There was a gradual rise in expression of the protein in the male reproductive tract during the critical period of Wolffian duct differentiation. The female reproductive tract produced only a trace immune reaction in Western analysis and no reaction in immunohistochemical analysis. Thus, the results support the hypothesis that the 72-kDa protein plays a role in Wolffian duct differentiation.

Animals↗
PubMed1995

Photoperiod times ontogeny of androgen receptor-immunoreactive cells in ferrets.

Regional increases in the density of androgen receptor-immunoreactive (AR-IR) brain cells are temporally correlated with pubertal maturation in male ferrets. If these increases in AR-IR cells are directly linked to pubertal maturation, then experimentally advancing the onset of puberty should similarly advance the timing of the increase in AR-IR cells. Photoinduction of pubertal maturation by transfer to long photoperiods advanced the onset of gonadal growth, elevated testosterone secretion and increased density of AR-IR cells in regions of the hypothalamus, relative to ferrets undergoing spontaneous pubertal maturation under short photoperiods. This experiment provides evidence that an increase in the density of AR-IR cells in specific brain regions is a neuroanatomical correlate of puberty that is also influenced by environmental day length.

Analysis of Variance↗
PubMed1984

Post-natal development of functional neurotransmission in rat vas deferens.

Responses of the rat vas deferens to drugs and to field stimulation were examined in sexually immature rats. The vasa from immature rats often exhibited spontaneous contractions and displayed greater sensitivity to the contractile effects of alpha-adrenoceptor agonists. The responses of the vasa from immature rats to single pulse field stimulation lacked the adrenergic component of the response although the non-adrenergic component was present. The responses were antagonized by alpha 2-adrenoceptor agonists. In the presence of cocaine, an adrenergic component of the response did appear. During trains of pulses the pre- and postjunctional effects of adrenergic transmission which are found in adult rats were absent in vasa from immature rats. Electron microscopic studies showed no qualitative differences in adrenergic innervation in vasa from immature and adult rats. It is concluded that a state of 'pre-innervation supersensitivity' associated with a lack of functional adrenergic transmission exists in the vas deferens of immature rats. The supersensitivity disappears and functional transmission develops during the period in which testosterone secretion increases in the rat. The reason for the lack of functional transmission at a time when the innervation appears to be morphologically mature is not clear but may be due to the noradrenaline release mechanism not being fully operative.

Adrenergic alpha-Agonists↗
PubMed2006

Effect of methanol extract of Ricinus communis seed on reproduction of male rats.

AIM: To investigate the effect of methanol extract of Ricinus communis seed (RCE) on male rats reproductive functions. METHODS: Thirty-two male albino rats were divided into four groups. Groups 1, 2 and 3 were gavaged with 0.2 mL of 2.5% tween 80 (RCE vehicle; control) or 20 mg/(kg x d) and 40 mg/(kg x d) of RCE, respectively, for 30 days, and group 4 was also gavaged with 40 mg/(kg x d) of RCE, but was allowed a recovery period of 30 days. Five untreated female rats were cohabited with male rats in each group from day 25 of RCE treatment for 5 days, except group 4, where cohabitation began on day 25 of the recovery period. All male rats were sacrificed 24 h after the experiments. The female rats were laparotomized on day 19 of pregnancy and the number and weight of litters were recorded. RESULTS: There was a significant decrease (P<0.01) in the weight of the reproductive organs, sperm functions and serum levels of testosterone in RCE treated rats. There was disorganization in the cytoarchitecture of the testes, disruption of the seminiferous tubules and erosion of the germinal epithelium. The number and weight of litters of rats in groups 2 and 4 decreased significantly (P<0.05) but no changes were observed in group 3. RCE caused no changes in liver, kidney, heart or body weights in male rats. CONCLUSION: RCE has a reversible negative impact on male reproductive functions, which appears to be mediated via gonadal disruption in testosterone secretion.

Animals↗
PubMed2006

Histological changes of the testis and epididymis in adult rats as a result of Leydig cell destruction after ethane dimethane sulfonate treatment: a morphometric study.

AIM: To quantitatively study the histological changes of the testis and epididymis as a result of a drastic reduction of testosterone secretion. METHODS: Fourteen adult Sprague-Dawley rats were injected intraperitoneally with ethane dimethane sulfonate (EDS, 75 mg/kg) and the same number of animals were injected with normal saline as a control. At days 7 and 12 (after treatment), respectively, half of the animals from each group were killed. The testes and epididymides were removed and tissue blocks embedded in methacrylate resin. The cell number per testis was estimated using the stereological optical disector and some other parameters were obtained using other morphometric methods. RESULTS: The EDS treatment resulted in an almost complete elimination of Leydig cells but had no effect on the numbers of Sertoli cells per testis. At day 7 after EDS treatment, many elongated spermatids were retained in the seminiferous epithelium and many round spermatids could be seen in the epididymal ducts. At day 12, a looser arrangement of spermatids and spermatocytes became evident, with apparent narrow empty spaces being formed between germ cells in an approximately radial direction towards the tubule lumen; the numbers (per testis) of non-type B spermatogonia and spermatocytes were similar to controls, whereas that of type B spermatogonia increased by 59%, and that of early round, elongating and late elongated spermatids decreased by 37%, 72% and 52%, respectively. CONCLUSION: The primary spermatogenic lesions following EDS administration were (i) spermiation failure and (ii) detachment of spermatids and spermatocytes associated with impairment in spermiogenesis and meiosis.

Animals↗
PubMed1996

Male pseudohermaphroditism secondary to panhypopituitarism.

An infant with a 46XY karyotype was born with ambiguous genitalia, including microphallus and perineal hypospadias. A female gender was assigned due to extreme failure of development of the external genitalia. Subsequent investigations demonstrated panhypopituitarism, and it is believed that severe gonadotrophin deficiency was responsible for the intersex state. This case illustrates the need to evaluate the hypothalamic-pituitary axis in selected cases of intersex, and also questions the prevailing assumption that testosterone secretion during embryogenesis is largely pituitary gonadotrophin independent, under the control of human chorionic gonadotrophin.

Disorders of Sex Development↗
PubMed1982

Gonadal function in Hodgkin's disease: long-term follow-up of chemotherapy.

A long-term study of gonadal function was conducted in 46 men and 28 women in prolonged remission of advanced Hodgkin's disease after cyclical combination chemotherapy with nitrogen mustard, vinblastine, prednisolone, and procarbazine. The mean follow-up was 6.9 years. Azoospermia or profound oligospermia occurred in 36 of the men, but late recovery was occasionally observed. Testosterone secretion was preserved. Amenorrhoea and gonadal hormone deficiency developed in 22 of the women and never recovered. Partial or complete chemical sterilisation and gonadal hormone deficiency is currently a consequence of cure of advanced Hodgkin's disease in most patients.

Adolescent↗
PubMed1984

Regulation of ovarian follicular growth and steroidogenesis by low-amplitude LH pulses.

A perifusion culture system controls the delivery of regulatory agents such that their concentration in the culture chamber is known at each and every point in time. The concentration in the culture chamber is predicted by the following equation: C(t) = Cf + (Ci - Cf)e(-R.t)/V, where C(t) is concentration in culture chamber (CC) at time t, Cf is concentration in holding flask (HF) (final CC concentration at t = infinity), Ci is initial CC concentration (t = 0), R is rate of media delivery from HF to CC (ml/h), V is volume of medium in CC (ml), and t is time (h). With this perifusion culture system, metestrous rat ovaries were exposed to tonic levels of follicle-stimulating hormone (FSH) and either tonic levels or hourly pulses of luteinizing hormone (LH). Both groups, however, received the same amount of FSH and LH. Compared with tonic levels, hourly pulses of LH increased estradiol-17 beta and suppressed testosterone secretion. In addition, pulsatile LH caused 1) a reduction in the atresia of small and midsized antral follicles, 2) an increase in atretic large follicles, and 3) an increase in the percent of growing midsized follicles. These results clearly demonstrate that ovarian responses depend on the pattern of LH stimulation. Since the LH pulses used in this study mimic in vivo metestrous levels, the LH pulses may be important in controlling ovarian function in vivo. The mechanism by which the ovary can distinguish between tonic and pulsatile stimuli remains to be determined.

Animals↗
PubMed1992

Analyses of plasma for metabolic and hormonal changes in rats flown aboard COSMOS 2044.

Plasma samples from rats flown aboard COS-MOS 2044 were analyzed for the levels of key metabolites, electrolytes, enzymes, and hormones. The major differences between the flight group and the synchronous control were elevations in glucose, cholesterol, phosphate, creatinine, blood urea nitrogen, lactate dehydrogenase, and aspartate amino-transferase and decreased levels of thyroxine. Most of these differences were not mimicked by tail suspension of ground-based rats; however, both flight and suspended rats exhibited inhibited testosterone secretion. Corticosterone, immunoreactive growth hormone, and prolactin showed inconsistent differences from the various control groups, suggesting that the levels of these hormones were not due to actual or simulated microgravity.

Adrenal Glands↗
PubMed1983

Extrahypothalamic brain luteinizing hormone: characterization by radioimmunoassay, chromatography, radioligand assay and bioassay.

We have recently reported that luteinizing hormone (LH) is present in the hypothalamus of rats. It has chromatographic and biologic characteristics similar to pituitary LH. In this report we focus on extrahypothalamic LH that is widely distributed in the rodent central nervous system. This material has a chromatographic profile similar to that of pituitary LH. Serial dilution of this material is parallel with dilutions of rat pituitary LH in the immunoassay. Brain extracts are active in the testis LH radioligand receptor assay and in the rat interstitial cell testosterone secretion bioassay. Prior incubation of extract with LH antibody significantly attenuated both of these activities. Thus, extrahypothalamic LH has immunologic, chromatographic, and biologic characteristics similar to hypothalamic and pituitary LH.

Animals↗
PubMed1994

Effects of exogenous androgen on brain androgen receptors of the fetal rhesus monkey.

Testosterone secreted by the fetal testes masculinizes and defeminizes the nonhuman primate brain during a defined prenatal critical period. We previously demonstrated the presence of high-affinity, specific androgen receptors (AR) in the developing rhesus monkey brain, but did not present data concerning their capacity for activation. To achieve this end, we analyzed the AR content in brains from intact and gonadectomized rhesus monkey fetuses at approximately 125 days of gestation, 2 h after injection of either 500 micrograms dihydrotestosterone (DHT) or vehicle directly into the fetus. After treatment, plasma DHT concentrations increased five-fold in the fetal circulation. In gonad-intact fetuses, cytosolic AR decreased in preoptic area, medial basal hypothalamus, and septum following DHT treatment. No significant effect of DHT treatment on nuclear AR was seen. In contrast, the increased level of DHT in the maternal circulation decreased cytosolic AR and increased nuclear AR of the maternal myometrium. In gonadectomized fetuses, DHT treatment decreased cytosolic AR as it did in the intact group. In contrast, a significant increase in nuclear AR was seen in preoptic area, medial basal hypothalamus, and tegmentum of these fetuses. Thus AR in fetal rhesus brain can be activated by DHT when the gonads are removed, but not in the intact fetuses. These data suggest that AR in the developing nervous system of rhesus macaques can be activated by exogenous androgen and hence are probably functional.

Androgens↗
PubMed1993

Reproductive aspects of testicular germ cell cancer: general discussion.

Gonadal function is affected by both chemotherapy and radiotherapy in the treatment of testicular cancer. Leydig cells are more resistant than germ cells, but endocrine function is also affected. Sex life is affected by treatment for testicular cancer but major permanent sexual dysfunction is not common. Radiotherapy is more damaging to Leydig cells than chemotherapy and can also cause direct effects on Sertoli cells. Leydig cell dysfunction following chemotherapy is dose-dependent. Serum FSH levels may be elevated at the time of primary orchidectomy and this may be used to predict ultimate fertility in these patients. Fertility does not recover if FSH levels are greater than 24 IU/l which is twice the upper limit of normal. Retroperitoneal lymph node dissection does not cause erectile dysfunction, but may cause dry ejaculation unless a nerve sparing operation is performed by an experienced surgeon. LHRH analogues causes reduced testosterone secretion, impotence and loss of libido, and requires exogenous androgen therapy. CIS can be eradicated by 20 Gy fractionated radiotherapy. This dose has been shown to have some effect on Leydig cell function but this is not clinically significant in the first 5 years of follow-up. The effects of lower doses of irradiation, which may be less injurious to Leydig cells, are currently being investigated. The effects of chemotherapy on CIS is as yet unpredictable.

Follicle Stimulating Hormone↗
PubMed2004

Sexual differentiation of the zebra finch song system.

The song system of zebra finches (Taeniopygia gutatta) is highly sexually dimorphic. Only males sing, and the brain regions and muscles controlling song are much larger in males than in females. Development of the song system is highly sensitive to steroid hormones. However, unlike similar sexually dimorphic systems in other animal models, masculinization of song system structure and function is most likely not induced by testosterone secreted from the testes. Instead, sex-specific development of the neural song system appears to be regulated by factors intrinsic to the brain, probably by the expression of sex chromosome gene(s) that influence the levels of estradiol synthesized in the brain and/or the responses of brain tissue to estradiol. However, the existing data are complex and in some cases contradictory. More work is required to identify the critical genes and their relationships with steroid hormones.

Androgens↗
PubMed2003

Spatiotemporal regulation of the two atrial natriuretic peptide receptors in testis.

By interacting with a guanylyl cyclase (GC) activity-containing receptor, termed GC-A, atrial natriuretic peptide (ANP) acts as a regulator of blood pressure and fluid volume homeostasis. High expression levels of GC-A in the testis and reported effects of ANP on testosterone secretion by Leydig cells are indicative of important local functions in this organ. Here we show, based on radioligand receptor labeling and immunological approaches, that seminiferous tubules rather than Leydig cells are the predominant GC-A expression sites in the rat testis. Functional activity was proved by ANP- induced cGMP accumulation in isolated seminiferous tubules. Although ontogenetic studies revealed a massive increase in GC-A levels during sexual maturation, the so-called natriuretic peptide clearance receptor, another type of ANP receptor proposed to locally control the availability of natriuretic peptides, was found to be expressed predominantly before puberty, exceeding the level of GC-A expression at this time. Natriuretic peptide clearance receptor also shows a distinct distribution pattern surrounding the seminiferous tubules. These findings raise the possibility of novel physiological roles for ANP and cGMP in the testis related to germ cell maturation and/or the regulation of the onset of puberty and suggest that the two ANP receptors function in a coordinated manner at this target organ.

Animals↗
PubMed2004

Ghrelin inhibits the proliferative activity of immature Leydig cells in vivo and regulates stem cell factor messenger ribonucleic acid expression in rat testis.

Ghrelin has emerged as putative regulator of an array of endocrine and nonendocrine functions, including cell proliferation. Recently, we provided evidence for the expression of ghrelin in mature, but not in undifferentiated, Leydig cells of rat and human testis. Yet testicular actions of ghrelin, other than modulation of testosterone secretion, remain unexplored. In the present study we evaluated the effects of ghrelin on proliferation of Leydig cell precursors during puberty and after selective elimination of mature Leydig cells by treatment with ethylene dimethane sulfonate. In these settings, intratesticular injection of ghrelin significantly decreased the proliferative activity of differentiating immature Leydig cells, estimated by 5-bromodeoxyuridine labeling. This response was selective and associated, in ethylene dimethane sulfonate-treated animals, with a decrease in the mRNA levels of stem cell factor (SCF), i.e. a key signal in spermatogenesis and a putative regulator of Leydig cell development. Thus, the effects of ghrelin on SCF gene expression were evaluated. In adult rats, ghrelin induced a significant decrease in SCF mRNA levels in vivo. Such an inhibitory action was also detected in vitro using cultures of staged seminiferous tubules. The inhibitory effect of ghrelin in vivo was dependent on proper FSH input, because it was detected in hypophysectomized rats only after FSH replacement. Overall, it is proposed that acquisition of ghrelin expression by Leydig cell precursors during differentiation may operate as a self-regulatory signal for the inhibition of the proliferative activity of this cell type through direct or indirect (i.e. SCF-mediated) mechanisms. In addition, we present novel evidence for the ability of ghrelin to modulate the expression of the SCF gene, which may have implications for the mode of action of this molecule in the testis as well as in other physiological systems.

Age Factors↗
PubMed1980

Effect of chronic alcohol ingestion on the biosynthesis of steroids in rat testicular homogenate in vitro.

The activity and kinetics of delta 5-3 beta-dehydrogenase and 17 alpha-hydroxylase, using labeled pregnenolone as substrate, were measured in gonadal homogenates from rats fed alcohol or isocalorically substituted carbohydrate for 40 days. There was no difference in the rate or reaction kinetics for either enzyme noted between control and alcohol-treated animals when the assays were carried out in the presence of saturating amounts of exogenous pyridine nucleotide cofactors. However, when exogenous cofactors were omitted from the reaction mixture, there was decreased activity of the delta 5-3 beta-dehydrogenase system and increased activity of the 17 alpha-hydroxylase reaction. Furthermore, a cofactor-specific inhibiting effect on delta 5-3 beta-dehydrogenase activity by NADH and NADPH was found. Incubation of gonadal homogenates from the alcohol-treated animals with pyruvate on lactate (in the absence of exogenous cofactors) resulted in an increase and a decrease, respectively, in enzyme activity. These studies indicate that chronic alcohol use decreases gonadal delta 5-3 beta-dehydrogenase activity and that this is most likely due to an effect of the agent on the concentration and/or availability of pyridine nucleotide cofactors rather than to a direct effect on the enzyme. This phenomenon may account for the mechanism by which alcohol decreases testosterone secretion in these animals.

Animals↗
PubMed1988

The effect of inhibition of aromatase enzyme activity on Leydig cell number and ultrastructure in beagles.

We have shown previously that administration of an orally active competitive aromatase inhibitor 4-(5,6,7,8-tetrahydroimidazo [1,5a] pyridin-5-yl) benzonitrile monohydrochloride to adult male beagles increases peripheral blood LH and testosterone concentrations, and that testes from treated dogs produce more testosterone when perfused in vitro than age-matched controls. In the present study we posed the question of whether the increased testosterone secretion by testes from these same aromatase-treated dogs was due to Leydig cell hypertrophy or hyperplasia, and if the latter, whether cytoplasmic organelles are increased. Beagles were treated with the inhibitor at a dosage of 2.5 mg/kg.day for 25 weeks and were euthanized by an overdose of iv sodium pentobarbital; testes were perfusion-fixed, embedded, and sectioned for stereological analysis. There were no significant differences in testis volume and absolute volumes of seminiferous tubules, blood vessels, lymphatic space, macrophage cells, and mesenchymal cells between the control and treated dogs. In contrast absolute interstitium volume and the absolute volume of Leydig cells per testis were significantly increased (P less than 0.05) in treated dogs. This increased Leydig cell volume per testis was due to increased volume of individual Leydig cells rather than to increases in Leydig cell number per testis. Additional studies showed that the surface area per Leydig cell of smooth endoplasmic reticulum, outer and inner mitochondrial membranes, and membranes of lipid droplets per testis were significantly higher (P less than 0.05) in the treated dogs as compared to the controls. In summary, the results of this study lead us to conclude that aromatase inhibition in the mature dog causes Leydig cell hypertrophy rather than hyperplasia and increased surface area per Leydig cell of subcellular organelles that contain enzymes involved in steroid biosynthesis.

Animals↗