Hormonal regulation of androgen production by the Leydig cell

The effects of peripheral hormone responses to exercise on adult hippocampal neurogenesis

Over the last decade, a considerable amount of new data have revealed the beneficial effects of exercise on hippocampal neurogenesis and the maintenance or improvement of cognitive function. Investigations with animal models, as well as human studies, have yielded novel understanding of the mechanisms through which endocrine signaling can stimulate neurogenesis, as well as the effects of exercise on acute and/or chronic levels of these circulating hormones. Considering the effects of aging on the decline of specific endocrine factors that affect brain health, insights in this area of research are particularly important. In this review, we discuss how different forms of exercise influence the peripheral production of specific endocrine factors, with particular emphasis on brain-derived neurotrophic factor, growth hormone, insulin-like growth factor-1, ghrelin, estrogen, testosterone, irisin, vascular endothelial growth factor, erythropoietin, and cortisol. We also describe mechanisms through which these endocrine responses to exercise induce cellular changes that increase hippocampal neurogenesis and improve cognitive function.

The Klinefelter Syndrome and Testicular Sperm Retrieval Outcomes

Klinefelter syndrome (KS), caused by the presence of an extra X chromosome, is the most prevalent chromosomal sexual anomaly, with an estimated incidence of 1:500/1000 per male live birth (karyotype 47,XXY). High stature, tiny testicles, small penis, gynecomastia, feminine body proportions and hair, visceral obesity, and testicular failure are all symptoms of KS. Endocrine (osteoporosis, obesity, diabetes), musculoskeletal, cardiovascular, autoimmune disorders, cancer, neurocognitive disabilities, and infertility are also outcomes of KS. Causal theories are discussed in addition to hormonal characteristics and testicular histology. The retrieval of spermatozoa from the testicles for subsequent use in assisted reproduction treatments is discussed in the final sections. Despite testicular atrophy, reproductive treatments allow excellent results, with rates of 40–60% of spermatozoa recovery, 60% of clinical pregnancy, and 50% of newborns. This is followed by a review on the predictive factors for successful sperm retrieval. The risks of passing on the genetic defect to children are also discussed. Although the risk is low (0.63%) when compared to the general population (0.5–1%), patients should be informed about embryo selection through pre-implantation genetic testing (avoids clinical termination of pregnancy). Finally, readers are directed to a number of reviews where they can enhance their understanding of comprehensive diagnosis, clinical care, and fertility preservation.

Effect of Tetragonia tetragonoides (Pall.) Kuntze Extract on Andropause Symptoms

Testosterone and free testosterone levels decrease in men as they age, consequently inducing andropause symptoms, such as weight gain, fatigue, and depression. Therefore, this study aimed to evaluate the reducing effect of New Zealand spinach (NZS) on these androgenic symptoms by orally administering its extract to 26-week-old rats for four weeks. Biochemical blood testing was conducted, and the andropause symptoms-related indicators and muscular endurance levels were examined. In the NZS extract-treated rats, the decrease in muscle mass was suppressed, and immobility time was reduced in the forced swim test. In addition, the grip force and muscular endurance of the forelimbs were significantly increased compared to the control group; therefore, NZS extract exhibits a positive effect on the maintenance of muscle mass and improves muscular endurance. The representative male hormones, testosterone and progesterone, in the NZS extract-treated group were 1.84 times and 2.48 times higher than those in the control groups, respectively. Moreover, cholesterol and low-density lipoprotein, which affect lipid metabolism, were significantly reduced in the NZS extract-treated group. Overall, NZS extract shows potential for further development as a functional food material for improving muscle strength and relieving andropause symptoms.

A Critical Review and Scientific Prospective on Contraceptive Therapeutics from Ayurveda and Allied Ancient Knowledge

Commonly used synthetic or prescribed hormonal drugs are known to interfere with the endocrine system and may have adverse reproductive, neurological, developmental, and metabolic effects in the body. These may also produce adverse effects such as polycystic ovarian disorder, endometriosis, early puberty, infertility or toxicity to gonads, testicular germ cell cancer, breast or prostate cancer, brain developmental problems, and even birth defects. Globally, the emergence of renewed interest in natural products for reproductive health is on the rise, which offers opportunities for new contraceptive developments. The search for alternate, safer contraceptive products or agents of natural origin is of scientific interest. Ayurvedic classical texts offer knowledge and information about the reproductive function and therapeutics including those for enhancement and limiting male and female fertility. Review of ancient, medieval, and recent—including texts on erotica that provide information on approaches and large numbers of formulations and drugs of plant, mineral or animal origin—claimed to have sterilizing, contraceptive, abortifacient, and related properties is presented. Few among these are known to be toxic and few are not so common. However, most of the formulations, ingredients, or modes of administration have remained unattended to, due to issues related to consumer compliance and limitations of standardization and lack of appropriate validation modalities. Several of these ingredients have been studied for their phytoconstituents and for the variety of pharmacological activities. Efforts to standardize several classical dosage forms and attempts to adapt to modern technologies have been made. List of formulations, ingredients, and their properties linked with known constituents, pharmacological, biological, and toxicity studies have been provided in a series of tables. The possible effectiveness and safety of selected formulations and ingredients have been examined. Suggestions based on new drug delivery systems integrated with advances in biotechnology, to provide prospects for new therapeutics for contraception, have been considered. Ayurveda is built on a holistic paradigm of biological entity rather than limited gonadal functions. Graphic presentation of a few carefully chosen possibilities has been depicted. New approaches to standardization and ethnopharmacological validation of natural contraceptive therapeutics may offer novel mechanisms and modalities and therapeutic opportunities to satisfy unmet needs of contraception.

Rising trends towards the development of oral herbal male contraceptive: an insight review

Background

Acknowledging population control to be an essential step for global health promotes wide research study in the area of male contraception. Although there are a great number of synthetic contraceptives available in the market, they have plenty of adverse effects. Different potential strategies for male contraception were investigated over a long period time consisting of hormonal, chemical, and immunological interventions, although these methods showed good antifertility results with low failure rates relative to condoms.

Main text

This review is based upon the concept of herbal contraceptives which are an effective method for controlling the fertility of animals and humans. This review has highlighted herbal medicinal plants and plant extracts which have been reported to possess significant antifertility action in males. The review considers those plants which are used traditionally for their spermicidal and antispermatogenic activities and imbalance essential hormones for fertility purposes and plants with reported animal studies as well as some with human studies for antifertility effect along with their doses, chemical constituents, and mechanism of action of the antifertility effect of the plants. This review also explains the phases of sperm formation, hormone production, and the mechanism of male contraceptives.

Conclusion

As far as the relevance of the current review is discussed, it might be quite useful in generating monographs on plants and recommendations on their use. A lot of the plant species listed here might appear promising as effective alternative oral fertility-regulating agents in males. Therefore, significant research into the chemical and biological properties of such less-explored plants is still needed to determine their contraceptive efficacy and also to possibly define their toxic effects so that these ingredients can be utilized with confidence to regulate male fertility. The new inventions in this field are necessary to concentrate on modern, more potent drugs with less harmful content and that are self-administrable, less costly, and entirely reversible.

Comparative Study of the Steroidogenic Effects of Human Chorionic Gonadotropin and Thieno[2,3-D]pyrimidine-Based Allosteric Agonist of Luteinizing Hormone Receptor in Young Adult, Aging and Diabetic Male Rats

Low-molecular-weight agonists of luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptor (LHCGR), which interact with LHCGR transmembrane allosteric site and, in comparison with gonadotropins, more selectively activate intracellular effectors, are currently being developed. Meanwhile, their effects on testicular steroidogenesis have not been studied. The purpose of this work is to perform a comparative study of the effects of 5-amino-N-tert-butyl-4-(3-(1-methylpyrazole-4-carboxamido)phenyl)-2-(methylthio)thieno[2,3-d] pyrimidine-6-carboxamide (TP4/2), a LHCGR allosteric agonist developed by us, and hCG on adenylyl cyclase activity in rat testicular membranes, testosterone levels, testicular steroidogenesis and spermatogenesis in young (four-month-old), aging (18-month-old) and diabetic male Wistar rats. Type 1 diabetes was caused by a single streptozotocin (50 mg/kg) injection. TP4/2 (20 mg/kg/day) and hCG (20 IU/rat/day) were administered for 5 days. TP4/2 was less effective in adenylyl cyclase stimulation and ability to activate steroidogenesis when administered once into rats. On the 3rd–5th day, TP4/2 and hCG steroidogenic effects in young adult, aging and diabetic rats were comparable. Unlike hCG, TP4/2 did not inhibit LHCGR gene expression and did not hyperstimulate the testicular steroidogenesis system, moderately increasing steroidogenic proteins gene expression and testosterone production. In aging and diabetic testes, TP4/2 improved spermatogenesis. Thus, during five-day administration, TP4/2 steadily stimulates testicular steroidogenesis, and can be used to prevent androgen deficiency in aging and diabetes.

Effects of gonadotropins on testis cell subpopulations of newly hatched chicks treated during embryonic development

The aim of the present study was to evaluate histological and stereological changes, as well as the variations in the number and size of cells from diverse cell subpopulations in testes of newly hatched chicks treated with follicle stimulating hormone (FSH) and luteinizing hormone (LH) during embryonic development. Stereological results indicated that in FSH-treated chicks total volume of the tubular compartment constitutes most of the testis. In contrast, the total volume of interstitial tissue constitutes most of the testis of LH-treated chicks. Results indicate that the number of germ and Sertoli cells increases as a result of FSH and LH treatment, but in FSH-treated testis, Sertoli cells were the most numerous cell type in seminiferous tubules; whereas germ cells were the most numerous cell type in testis of LH-treated chicks. Results also indicate there was a larger total volume of Leydig cells in the testes of FSH- and LH-treated chicks. The larger volume of Leydig cells in FSH-treated chicks is due to a larger cellular volume of these cells, and not due to the number, which remains constant. In contrast, in testes of LH-treated chicks, there is a larger number and volume of Leydig cells. These results indicate the testes of chick embryos respond to FSH and LH treatment, with there being modifications in the seminiferous tubules and interstitial tissue, but these changes differ markedly, indicating that FSH and LH have differential effects on chick testes.

Androgen receptor signaling in the lungs mitigates inflammation and improves the outcome of influenza in mice

Circulating androgens can modulate immune cell activity, but the impact of androgens on viral pathogenesis remains unclear. Previous data demonstrate that testosterone reduces the severity of influenza A virus (IAV) infection in male mice by mitigating pulmonary inflammation rather than by affecting viral replication. To examine the immune responses mediated by testosterone to mitigate IAV-induced inflammation, adult male mice remained gonadally intact or were gonadectomized and treated with either placebo or androgen-filled (i.e., testosterone or dihydrotestosterone) capsules prior to sublethal IAV infection. Like intact males, treatment of gonadectomized males with androgens improved the outcome of IAV infection, which was not mediated by changes in the control of virus replication or pulmonary cytokine activity. Instead, androgens accelerated pulmonary leukocyte contraction to limit inflammation. To identify which immune cells were contracting in response to androgens, the composition of pulmonary cellular infiltrates was analyzed and revealed that androgens specifically accelerated the contraction of total pulmonary inflammatory monocytes during peak disease, as well as CD8+ T cells, IAV-specific CD8+ T numbers, cytokine production and degranulation by IAV-specific CD8+ T cells, and the influx of eosinophils into the lungs following clearance of IAV. Neither depletion of eosinophils nor adoptive transfer of CD8+ T cells could reverse the ability of testosterone to protect males against IAV suggesting these were secondary immunologic effects. The effects of testosterone on the contraction of immune cell numbers and activity were blocked by co-administration of the androgen receptor antagonist flutamide and mimicked by treatment with dihydrotestosterone, which was also able to reduce the severity of IAV in female mice. These data suggest that androgen receptor signaling creates a local pulmonary environment that promotes downregulation of detrimental inflammatory immune responses to protect against prolonged influenza disease.

Insulin/IGF1 signaling regulates the mitochondrial biogenesis markers in steroidogenic cells of prepubertal testis, but not ovary

Controlled changes in mitochondrial biogenesis and morphology are required for cell survival and homeostasis, but the molecular mechanisms are largely unknown. Here, male and female prepubertal mice (P21) with insulin and IGF1 receptors deletions in steroidogenic tissues (Insr/Igf1r-DKO) were used to investigate transcription of the key regulators of mitochondrial biogenesis (Ppargc1a, Ppargc1b, Pparg, Nrf1, Tfam) and architecture in Leydig cells, ovaries, and adrenals. Results showed that the expression of PGC1, a master regulator of mitochondrial biogenesis and integrator of environmental signals, and its downstream target Tfam, significantly decreased in androgen-producing Leydig cells. This is followed by reduction of Mtnd1, a mitochondrial DNA encoded transcript whose core subunit belongs to the minimal assembly required for catalysis. The same markers remained unchanged in ovaries. In contrast, in adrenals, the pattern of transcripts for mitochondrial biogenesis markers was the same in both sexes, but opposite from that observed in Leydig cells. The level of transcripts for markers of mitochondrial architecture (Mfn1, Mfn2) significantly increased in Leydig cells from Insr/Igf1r-DKO, but not in ovaries. This was followed by mitochondrial morphology disturbance, suggesting that the mitochondrial phase of steroidogenesis could be affected. Indeed, basal and pregnenolone stimulated progesterone productions in the mitochondria of Leydig cells from Insr/Igf1r-DKO decreased more than androgen production, and were barely detectable. Our results are the first to show that INSR/IGF1R are important for mitochondrial biogenesis in gonadal steroidogenic cells of prepubertal males, but not females and they serve as important regulators of mitochondrial architecture and biogenesis markers in Leydig cells.

Constipation and diarrhea during the menopause transition and early postmenopause: observations from the Seattle Midlife Women's Health Study

OBJECTIVE

To assess the relationship of constipation and diarrhea severity during the menopause transition (MT) with age, MT stage, reproductive biomarkers, stress-related biomarkers, and stress-related perceptions.

METHODS

From 1990 to 1992, women aged 35 to 55 years were recruited from the greater Seattle area; 291 of them consented to ongoing (1990-2013) annual data collection by daily menstrual calendar, health diary, and annual health questionnaire. A subset (n = 131) provided a first morning voided urine specimen (1997-2013). These were assayed for levels of E1G, follicle-stimulating hormone, testosterone, cortisol, norepinephrine, and epinephrine. Mixed-effects modeling was used to identify how changes in constipation and diarrhea severity over time related to age, MT stage, reproductive biomarkers, stress-related biomarkers, and stress-related perceptions.

RESULTS

In a univariate model, age, late reproductive (LR) stage, tension, and anxiety were all significantly and positively related to constipation severity, whereas cortisol was significantly and negatively associated. In a multivariate model, only tension and cortisol remained significant predictors of constipation severity (P < 0.05). In a univariate model, age, LR stage, and estrone glucuronide were significantly and negatively associated with diarrhea severity, whereas tension, anxiety, and perceived stress were significantly and positively related. In a multivariate model, only tension and age remained significant predictors of diarrhea severity.

CONCLUSIONS

Key reproductive hormones do not play a significant role in constipation or diarrhea severity in the MT. In contrast, stress perception, tension, anxiety, and cortisol do. These factors should be evaluated in further research involving constipation and diarrhea.

Abdominal pain during the menopause transition and early postmenopause: observations from the Seattle Midlife Women's Health Study

Objective

To assess the relationship between abdominal pain severity during the menopausal transition (MT) and age, MT stage, reproductive biomarkers, stress biomarkers, and stress perceptions.

Methods

Women ages 35-55 were recruited from multiethnic neighborhoods in the greater Seattle area from 1990 to 1992, for an original study cohort of 508. From 1990 to 2013, a subset of this cohort consented to ongoing annual data collection by annual health questionnaire, health diary, and daily menstrual calendar. Beginning in 1997, a portion of these women also provided a first morning voided urine specimen to be assayed for levels of estrone glucuronide (E₁G), follicle stimulating hormone (FSH), testosterone, cortisol, norepinephrine, and epinephrine. To identify how changes in abdominal pain severity changed over time in relation to age, MT stage, reproductive biomarkers, stress-related biomarkers, and stress-related perceptions, mixed effects modeling was used.

Results

In a univariate model, E₁G (p = 0.02) and testosterone (p = 0.02) were significantly and negatively related to abdominal pain severity, while perceived stress (p = 0.06), tension (p <  0.001), and anxiety (p <  0.001) were significantly and positively associated. In a multivariate model, increasing age (p = 0.001) and E₁G (p = 0.04) were negatively associated with abdominal pain severity, and anxiety (p = 0.00) positively associated. Testosterone did not improve the fit to the final model, nor did tension or perceived stress.

Conclusions

These results suggest that age, anxiety, and E₁G each show a significant association with abdominal pain severity in the MT. In contrast, stress perception, tension, testosterone, stress biomarkers, and MT stage do not. These factors should be evaluated further in research on abdominal pain experienced during the MT and early postmenopause years.

The relationships between urinary phthalate metabolites, reproductive hormones and semen parameters in men attending in vitro fertilization clinic

Evidence from previous studies has shown that phthalates may play a role in male reproductive function; however, results are still inconclusive, and the mechanism remains unclear. In this study, we first assessed whether exposure to phthalates is associated with altered reproductive hormones and semen parameters in 599 men attending an in vitro fertilization clinic. Secondly, we evaluated whether reproductive hormones could play a mediating role in the association between phthalates and sperm parameters. Eight phthalate metabolites were measured in two different spot urine samples: mono‑n‑butyl phthalate, mono-isobutyl phthalate (MiBP), monoethyl phthalate (MEP), monobenzyl phthalate, and four oxidative metabolites of di‑(2‑ethylhexyl) phthalate (DEHP) [i.e., mono‑(2‑ethylhexyl) phthalate (MEHP), mono‑(2‑ethyl‑5‑hydroxyhexyl) phthalate (MEHHP), mono‑(2‑ethyl‑5‑oxohexyl) phthalate (MEOHP), and mono‑(2‑ethyl‑5‑carboxypentyl) phthalate (MECPP)]. Semen parameters (concentration, volume, motility, and morphology) and reproductive hormones, i.e., follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone, estradiol (E₂), testosterone (TEST) and prolactin (PROL) were also determined and considered the main study outcomes. Separate multivariate linear regression was used to assess associations between levels of each urinary phthalate metabolite, molar sum of DEHP metabolites (∑DEHP), percentage of MEHP to ∑DEHP (%MEHP), and each outcome (natural log-transformed). Inverse associations were observed between TEST and MiBP (β = -0.099), FSH and MEHHP (β = -0.087), and PROL and MEOHP (β = -0.102), while a positive relationship was seen between E₂ and MEP (β = 0.098). %MEHP was associated positively with FSH (β = 0.118) and LH (β = 0.099), but negatively with TEST/LH (β = -0.086) and TEST/E₂ (β = -0.109). Sperm concentration was associated positively with MECPP (β = 0.131), MEHHP (β = 0.117), MEOHP (β = 0.107) and ∑DEHP (β = 0.111), but negatively with %MEHP (β = -0.135). All p-values were <0.05. Sobel's test indicated that FSH mediated significantly up to 60% of the positive relationship between sperm concentration and MEHHP, while FSH and LH mediated respectively 15 and 12% of the inverse association between sperm concentration and %MEHP. Further research on this topic is warranted.

Calcium-dependent Nr4a1 expression in mouse Leydig cells requires distinct AP1/CRE and MEF2 elements

The nuclear receptor NR4A1 is expressed in steroidogenic Leydig cells where it plays pivotal roles by regulating the expression of several genes involved in steroidogenesis and male sex differentiation including Star, HSD3B2, and Insl3 Activation of the cAMP and Ca(2+) signaling pathways in response to LH stimulation leads to a rapid and robust activation of Nr4a1 gene expression that requires the Ca(2+)/CAMKI pathway. However, the downstream transcription factor(s) have yet to be characterized. To identify potential Ca(2+)/CaM effectors responsible for hormone-induced Nr4a1 expression, MA-10 Leydig cells were treated with forskolin to increase endogenous cAMP levels, dantrolene to inhibit endoplasmic reticulum Ca(2+) release, and W7 to inhibit CaM activity. We identified Ca(2+)-responsive elements located in the discrete regions of the Nr4a1 promoter, which contain binding sites for several transcription factors such as AP1, CREB, and MEF2. We found that one of the three AP1/CRE sites located at -255 bp is the most responsive to the Ca(2+) signaling pathway as are the two MEF2 binding sites at -315 and -285 bp. Furthermore, we found that the hormone-induced recruitment of phospho-CREB and of the co-activator p300 to the Nr4a1 promoter requires the Ca(2+) pathway. Lastly, siRNA-mediated knockdown of CREB impaired NR4A1 expression and steroidogenesis. Together, our data indicate that the Ca(2+) signaling pathway increases Nr4a1 expression in MA-10 Leydig cells, at least in part, by enhancing the recruitment of coactivator most likely through the MEF2, AP1, and CREB transcription factors thus demonstrating an important interplay between the Ca(2+) and cAMP pathways in regulating Nr4a1 expression.

Stress triggers mitochondrial biogenesis to preserve steroidogenesis in Leydig cells

Adaptability to stress is a fundamental prerequisite for survival. Mitochondria are a key component of the stress response in all cells. For steroid-hormones-producing cells, including also Leydig cells of testes, the mitochondria are a key control point for the steroid biosynthesis and regulation. However, the mitochondrial biogenesis in steroidogenic cells has never been explored. Here we show that increased mitochondrial biogenesis is the adaptive response of testosterone-producing Leydig cells from stressed rats. All markers of mitochondrial biogenesis together with transcription factors and related kinases are up-regulated in Leydig cells from rats exposed to repeated psychophysical stress. This is followed with increased mitochondrial mass. The expression of PGC1, master regulator of mitochondrial biogenesis and integrator of environmental signals, is stimulated by cAMP-PRKA, cGMP, and β-adrenergic receptors. Accordingly, stress-triggered mitochondrial biogenesis represents an adaptive mechanism and does not only correlate with but also is an essential for testosterone production, being both events depend on the same regulators. Here we propose that all events induced by acute stress, the most common stress in human society, provoke adaptive response of testosterone-producing Leydig cells and activate PGC1, a protein required to make new mitochondria but also protector against the oxidative damage. Given the importance of mitochondria for steroid hormones production and stress response, as well as the role of steroid hormones in stress response and metabolic syndrome, we anticipate our result to be a starting point for more investigations since stress is a constant factor in life and has become one of the most significant health problems in modern societies.

A cell-autonomous molecular cascade initiated by AMP-activated protein kinase represses steroidogenesis

Steroid hormones regulate essential physiological processes, and inadequate levels are associated with various pathological conditions. In testosterone-producing Leydig cells, steroidogenesis is strongly stimulated by luteinizing hormone (LH) via its receptor leading to increased cyclic AMP (cAMP) production and expression of the steroidogenic acute regulatory (STAR) protein, which is essential for the initiation of steroidogenesis. Steroidogenesis then passively decreases with the degradation of cAMP into AMP by phosphodiesterases. In this study, we show that AMP-activated protein kinase (AMPK) is activated following cAMP-to-AMP breakdown in MA-10 and MLTC-1 Leydig cells. Activated AMPK then actively inhibits cAMP-induced steroidogenesis by repressing the expression of key regulators of steroidogenesis, including Star and Nr4a1. Similar results were obtained in Y-1 adrenal cells and in the constitutively steroidogenic R2C cells. We have also determined that maximum AMPK activation following stimulation of steroidogenesis in MA-10 Leydig cells occurs when steroid hormone production has reached a plateau. Our data identify AMPK as a molecular rheostat that actively represses steroid hormone biosynthesis to preserve cellular energy homeostasis and prevent excess steroid production.

The opposite roles of glucocorticoid and α1-adrenergic receptors in stress triggered apoptosis of rat Leydig cells

The stress-induced initiation of proapoptotic signaling in Leydig cells is relatively well defined, but the duration of this signaling and the mechanism(s) involved in opposing the stress responses have not been addressed. In this study, immobilization stress (IMO) was applied for 2 h daily, and animals were euthanized immediately after the first (IMO1), second (IMO2), and 10th (IMO10) sessions. In IMO1 and IMO2 rats, serum corticosterone and adrenaline were elevated, whereas serum androgens and mRNA transcription of insulin-like factor-3 in Leydig cells were inhibited. Reduced oxygen consumption and the mitochondrial membrane potential coupled with a leak of cytochrome c from mitochondria and increased caspase-9 expression, caspase-3 activity, and number of apoptotic Leydig cells was also observed. Corticosterone and adrenaline were also elevated in IMO10 rats but were accompanied with a partial recovery of androgen secretion and normalization of insulin-like factor-3 transcription coupled with increased cytochrome c expression, abolition of proapoptotic signaling, and normalization of the apoptotic events. Blockade of intratesticular glucocorticoid receptors diminished proapoptotic effects without affecting antiapoptotic effects, whereas blockade of intratesticular α(1)-adrenergic receptors diminished the antiapoptotic effects without affecting proapoptotic effects. These results confirmed a critical role of glucocorticoids in mitochondria-dependent apoptosis and showed for the first time the relevance of stress-induced upregulation of α(1)-adrenergic receptor expression in cell apoptotic resistance to repetitive IMOs. The opposite role of two hormones in control of the apoptotic rate in Leydig cells also provides a rationale for a partial recovery of androgen production in chronically stressed animals.

The calcium signaling pathway regulates leydig cell steroidogenesis through a transcriptional cascade involving the nuclear receptor NR4A1 and the steroidogenic acute regulatory protein

In the gonads and adrenal glands, the transient increase in steroidogenesis after hormonal stimulation requires modulation of steroidogenic acute regulatory protein (Star) expression and activity in a tightly regulated process involving cAMP and Ca(2+). In Leydig cells, the cAMP and Ca(2+) pathways account for most if not all of LH-induced steroidogenesis. Although the cAMP-activated molecular network has been well characterized in Leydig cells, little is known about the molecular cascade triggered by the Ca(2+) signaling pathway and the transcription factors responsible for mediating the genomic response. It is established that LH induces an increase in cytoplasmic Ca(2+) from the endoplasmic reticulum primarily through the ryanodine receptors. Previous reports also suggested a role of the Ca(2+) signaling pathway in Star expression based on the fact that inhibition of the Ca(2+)/calmodulin (CaM) protein kinase pathway greatly impaired Star expression in Leydig and adrenal cells. In this study, we used ryanodine receptors and CaM antagonists to show that the increase in intracellular Ca(2+) level is an essential modulator of progesterone synthesis through the regulation of Star gene expression in MA-10 Leydig cells. Furthermore, we mapped a Ca(2+)/CaM-sensitive element in the Star promoter, which led to the identification of the nuclear receptor 4A1 (NR4A1) as a key mediator of the Ca(2+)/CaM signaling pathway in these cells. These data provide new insights into the Ca(2+) molecular pathway essential for steroidogenesis in Leydig cells.

The effect of CRH and its inhibitor, antalarmin, on in vitro growth of preantral mouse follicles, early embryo development, and steroidogenesis

In vitro growth systems of preantral follicles allow studying the effect of various endocrine, paracrine, and autocrine factors on follicular growth and oocyte maturation. CRH is a 41-amino-acid neuropeptide responsible for endocrine, autonomic, immunological, and behavioral responses of mammals to stress and has two receptors, CRH receptor type 1 (CRH-R1) and CRH-R2. Antalarmin, a CRH-R1 antagonist, has been used to elucidate the role of CRH in stress, inflammation, and reproduction. The present study describes in vitro growth of mouse preantral follicles, early embryo development, and steroidogenesis in the presence of CRH and its antagonist antalarmin. We cultured 732 follicles in control media, 1306 in CRH 10(-7) mol/liter, and 1202 in CRH 10(-7) plus antalarmin 10(-6) mol/liter. The culture medium was assayed on alternate days for 17β-estradiol, progesterone, and β-human chorionic gonadotropin. Total RNA was extracted from preantral follicles as well as early preimplantation embryos and was assessed by real-time RT-PCR for the expression of CRH-R1 and CRH-R2 mRNAs. Hormone analysis showed that the CRH group had lower levels of 17β-estradiol, progesterone, and β-human chorionic gonadotropin as the culture progressed, in comparison with the other two groups. RT-PCR demonstrated the presence of CRH-R1 and CRH-R2 in all stages of preantral follicle culture. Morula/blastocyst-stage embryos expressed only CRH-R1. In conclusion, CRH has an inhibitory effect on in vitro fertilized oocytes, resulting from cultured preantral follicles at all stages of preimplantation embryo development. Furthermore, the presence of CRH in the culture medium inhibits steroidogenesis by preantral mouse follicles cultured in vitro.

The potentiality of medicinal plants as the source of new contraceptive principles in males

Rising human population throughout the world especially in developing and underdeveloped countries has detrimental effects on life supporting system on earth. Traditionally, plants have been used to treat different kinds of ailments. The growing importance of phytochemicals in males has been reported. Contraceptive ability of plants has been reported in several animal models. The reversibility of the anti-fertility effects of plants and its active compounds are of potential clinical relevance in the development of male contraceptive. This review attempts to discuss the latest reports on the potentiality of medicinal plants as the source of new contraceptive principles in males.

Analysis of the impact of intravenous LH pulses versus continuous LH infusion on testosterone secretion during GnRH-receptor blockade

Gonadotrophin-releasing hormone (GnRH) pulsatility is required for optimal luteinizing hormone (LH) secretion, but whether LH pulsatility is required for physiological testosterone (T) secretion is not known. To test the postulate that pulses of recombinant human (rh) LH stimulate greater T secretion than continuous infusion of the same dose, a potent selective GnRH antagonist was administered overnight to 19 healthy men ages 18-49 yr. Subjects then received saline or rhLH intravenously continuously or as 6-min pulses intravenously every 1 or 2 h at the same total dose. Blood was sampled every 10 min for 10 h to quantify T responses. For the four interventions, the descending rank order of mean LH and mean T concentrations was 1-h = 2-h rhLH pulses > continuous rhLH > saline (P < 10(-3)). Plateau LH and T concentrations correlated positively (R(2) = 0.943, P = 0.029) as did LH concentrations and LH half-lives (R(2) = 0.962, P = 0.019). Percentage pulsatile T secretion assessed by deconvolution analysis (Keenan DM, Takahashi PY, Liu PY, Roebuck PD, Nehra AX, Iranmanesh A, Veldhuis JD. Endocrinology 147: 2817-2828, 2006) was the highest (P = 0.019), and half-time to attain peak T concentrations was the shortest (P < 10(-6)), for 1-h rhLH pulses. Approximate entropy (a pattern-regularity measure) revealed more orderly T secretion for 1- than 2-h rhLH pulses (P = 0.0076). Accordingly, a pulsatile LH signal, while not obligatory to maintain mean T concentrations, controls the mean plasma LH concentration and determines quantifiable patterns of T secretion. These data introduce the question whether blood T patterns in turn supervise distinctive target-tissue responses.

BLTK1 murine Leydig cells: a novel steroidogenic model for evaluating the effects of reproductive and developmental toxicants

Leydig cells are the primary site of androgen biosynthesis in males. Several environmental toxicants target steroidogenesis resulting in both developmental and reproductive effects including testicular dysgenesis syndrome. The aim of this study was to evaluate the effect of several structurally diverse endocrine disrupting compounds (EDCs) on steroidogenesis in a novel BLTK1 murine Leydig cell model. We demonstrate that BLTK1 cells possess a fully functional steroidogenic pathway that produces low basal levels of testosterone (T) and express all the necessary steroidogenic enzymes including Star, Cyp11a1, Cyp17a1, Hsd3b1, Hsd17b3, and Srd5a1. Recombinant human chorionic gonadotropin (rhCG) and forskolin (FSK) elicited concentration- and time-dependent induction of 3',5'-cyclic adenosine monophosphate, progesterone (P), and T, as well as the differential expression of Star, Hsd3b6, Hsd17b3, and Srd5a1 messenger RNA levels. The evaluation of several structurally diverse male reproductive toxicants including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), atrazine, prochloraz, triclosan, monoethylhexyl phthalate (MEHP), glyphosate, and RDX in BLTK1 cells suggests different modes of action perturb steroidogenesis. For example, prochloraz and triclosan antifungals reduced rhCG induction of T, consistent with published in vivo data but did not alter basal T levels. In contrast, atrazine and MEHP elicited modest induction of basal T but antagonized rhCG-mediated induction of T levels, whereas TCDD, glyphosate, and RDX had no effect on basal or rhCG induction of T in BLTK1 cells. These results suggest that BLTK1 cells maintain rhCG-inducible steroidogenesis and are a viable in vitro Leydig cell model to evaluate the effects of EDCs on steroidogenesis. This model can also be used to elucidate the different mechanisms underlying toxicant-mediated disruption of steroidogenesis.

Influence of multiple injections of human chorionic gonadotropin (hCG) on urine and serum endogenous steroids concentrations

Since it is established that human chorionic gonadotropin (hCG) affects testosterone production and release in the human body, the use of this hormone as a performance enhancing drug has been prohibited by the World Anti-Doping Agency. Nowadays, the only validated biomarker of a hCG doping is its direct quantification in urine. However, this specific parameter is subjected to large inter-individual variability and its determination is directly dependent on the reliability of hCG immunoassays used. In order to counteract these weaknesses, new biomarkers need to be evidenced. To address this issue, a pilot clinical study was performed on 10 volunteers submitted to 3 subsequent hCG injections. Blood and urine samples were collected during two weeks in order to follow the physiological effects on related compounds such as the steroid profile or hormones involved in the hypothalamo-pituitary axis. The hCG pharmacokinetic observed in all subjects was, as expected, prone to important inter-individual variations. Using ROC plots, level of testosterone and testosterone on luteinizing hormone ratio in both blood and urine were found to be the most relevant biomarker of a hCG abuse, regardless of inter-individual variations. In conclusion, this study showed the crucial importance of reliable quantification methods to assess low differences in hormonal patterns. In regard to these results and to anti-doping requirements and constraints, blood together with urine matrix should be included in the anti-doping testing program. Together with a longitudinal follow-up approach it could constitute a new strategy to detect a hCG abuse, applicable to further forms of steroid or other forbidden drug manipulation.

Pain symptoms during the menopausal transition and early postmenopause

AIM

The aim of this study was to describe changes in levels of back pain and joint pain during the stages of menopausal transition stages and early postmenopause, including the effects of age, menopausal transition-related factors (estrone, follicle stimulating hormone (FSH), testosterone), menopausal transition stages, symptoms (hot flush, sleep, mood, cognitive), health-related factors (body mass index, alcohol use, smoking, well-being), stress-related factors (perceived stress, history of sexual abuse, cortisol, catecholamines) and social factors (partner and parenting status, education).

METHODS

A subset was studied of the participants in the Seattle Midlife Women's Health Study who provided data during the late reproductive, early and late menopausal transition stages or postmenopause (n = 292) including menstrual calendars for staging the menopausal transition, annual health reports completed between 1990 and 2006, and morning urine samples assayed for estrone glucuronide (E(1)G), testosterone, FSH, cortisol and catecholamines, and symptom diary ratings several times each year. Multilevel modeling with an R program was used to test patterns of pain symptoms related to age, menopausal transition-related factors, symptoms, health-related, stress-related and social factors, with as many as 6812 observations. Age was centered at 47.4 years.

RESULTS

Women experienced a slight, non-significant rise in back pain with age and a significant increase in back pain during the early (p = 0.003) and late menopausal transition stages (p = 0.002) and early postmenopause (p = 0.02), but urinary E(1)G, FSH and testosterone levels were unrelated. Of the stress-related factors, perceived stress (p = 0.01) and lower overnight urinary cortisol levels were associated with more severe back pain (p = 0.03); history of sexual abuse and catecholamines did not have a significant effect. Those most troubled by symptoms of hot flushes, depressed mood, anxiety, night-time awakening, and difficulty concentrating reported significantly greater back pain (all p < 0.0001). Of the health-related factors, having worse perceived health (p < 0.0001), exercising more (p = 0.005), using analgesics (p < 0.0001), and having a higher body mass index (p < 0.0001) were associated with more back pain, but alcohol use and smoking did not have significant effects. Of the social factors, only having a more formal education (p = 0.004) was associated with less back pain; parenting, having a partner, and employment were not significant. Factors associated with joint pain included age (p < 0.0001), but not menopausal transition-related factors. Symptoms of hot flushes, night-time awakening, depressed mood, and difficulty concentrating were each significantly associated with joint pain (p < 0.0001). Poorer perceived health, more exercise, higher body mass index, and greater analgesic use were all associated similarly with joint pain. History of sexual abuse was the only stress-related factor significantly related to joint pain severity (p = 0.024).

IMPLICATIONS

Clinicians working with women traversing the menopausal transition should be aware that managing back and joint pain symptoms among mid-life women requires consideration of their changing biology as well as their ongoing life challenges and health-related behaviors.

Effects of plants and plant products on the testis

For centuries, plants and plant-based products have been used as a valuable and safe natural source of medicines for treating various ailments. The therapeutic potential of most of these plants could be ascribed to their anticancer, antidiabetic, hepatoprotective, cardioprotective, antispasmodic, analgesic and various other pharmacological properties. However, several commonly used plants have been reported to adversely affect male reproductive functions in wildlife and humans. The effects observed with most of the plant and plant-based products have been attributed to the antispermatogenic and/or antisteroidogenic properties of one or more active ingredients. This review discusses the detrimental effects of some of the commonly used plants on various target cells in the testis. A deeper insight into the molecular mechanisms of action of these natural compounds could pave the way for developing therapeutic strategies against their toxicity.

Sleep symptoms during the menopausal transition and early postmenopause: observations from the Seattle Midlife Women's Health Study

STUDY OBJECTIVES

Describe the severity of getting to sleep, nighttime awakening, and early morning awakening across the menopausal transition (MT) and early postmenopause (PM) and their relationship to age, menopausal transition factors, symptoms, stress-related factors, and health related factors.

DESIGN

Cohort.

SETTING

community.

PARTICIPANTS

286 women from the Seattle Midlife Women's Health Study cohort.

MEASUREMENTS

Participants completed annual menstrual calendars for MT staging, diaries in which they rated their symptoms, stress levels, and perceived health multiple times per year from 1990-2007 and provided first morning urine samples assayed for E1G, FSH, cortisol, and catecholamines. Multilevel modeling (R program) was used for data analysis.

RESULTS

Severity of self-reported problems going to sleep was associated with all symptoms, perceived stress, history of sexual abuse, perceived health (-), alcohol use (-) (all P < 0.001), and lower cortisol (P = 0.009), but not E1G or FSH. Severity of nighttime awakening was significantly associated with age, late MT stage, and early PM, FSH, E1G (-), hot flashes, depressed mood, anxiety, joint pain, backache, perceived stress, history of sexual abuse, perceived health (-), and alcohol use (-) (all P < 0.001, except E1G for which P = 0.030). Severity of early morning awakening was significantly associated with age, hot flashes, depressed mood anxiety, joint pain, backache, perceived stress, history of sexual abuse, perceived health (-) (all P < or = 0.001, except E1G for which P = 0.02 and epinephrine (P = 0.038), but not MT stages or FSH. Multivariate models for each symptom included hot flashes, depressed mood, and perceived health.

CONCLUSION

Sleep symptoms during the MT may be amenable to symptom management strategies that take into account the symptom clusters and promote women's general health rather than focusing only on the MT.

Inhibition of cyclooxygenase-2 down-regulates aromatase activity and decreases proliferation of Leydig tumor cells

Our recent studies have revealed that estrogens stimulate an autocrine mechanism determining Leydig tumor cell proliferation. Estrogen overproduction is due to an elevated steroidogenic factor-1 (SF-1) expression and cAMP-response element-binding protein (CREB) phosphorylation, both inducing aromatase overexpression. Although we have shown that increased SF-1 expression depends mainly on higher local insulin-like growth factor I production, the mechanisms and factors determining increased CREB activation in Leydig tumor cells are not completely understood. In this study, we investigated the role of cyclooxygenase-2 (COX-2) in CREB dependent-aromatase expression in Leydig tumor cells. We found that COX-2 is expressed in rat and human Leydigiomas as well as in the rat Leydig tumor cell line R2C, but not in normal testis. Our data indicate that in R2C cells the COX-2-derived prostaglandin E2 (PGE2) binds the PGE2 receptor EP4 and activates protein kinase A (PKA) and ultimately CREB. Inhibitors for COX-2 (NS398), EP4 (AH23848), and PKA (H89) decreased aromatase expression and activity as a consequence of a decreased phosphorylated CREB recruitment to the PII promoter of the aromatase gene. The COX-2/PGE2/PKA pathway also seems to be involved in aromatase post-translational activation, an observation that requires further studies. The reduction in aromatase activity was responsible for a drop in estrogen production and subsequent reduction in cyclin E expression resulting in a decrease in tumor Leydig cell proliferation. Furthermore, COX-2 silencing caused a significant decrease in CREB phosphorylation, aromatase expression, and R2C cell proliferation. These novel findings clarify the mechanisms involved in the growth of Leydig cell tumors and should be taken into account in determining new therapeutic approaches.

Effects of aromatase inhibition in hypogonadal older men: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To assess the effects of sustained aromatase inhibition in older hypogonadal men.

DESIGN AND PATIENTS

In a 1-year randomized, double-blind, placebo-controlled trial, 88 men, aged 60 and older with testosterone levels between 5.2 and 10.4 nmol/L on a single measure or between 10.4 and 12.1 nmol/L on two consecutive measures, and symptoms of hypogonadism were recruited. Subjects received either anastrozole 1 mg daily or placebo.

MEASUREMENTS

Changes in gonadal steroid hormone levels, body composition (by computerized tomography (CT) and dual x-ray absorptiometry (DXA)), strength, prostate specific antigen (PSA), symptoms of benign prostatic hypertrophy (BPH), hematocrit and lipid levels were assessed.

RESULTS

Testosterone levels increased from 11.2 +/- 3.3 nmol/L at baseline to 18.2 +/- 4.8 nmol/L at month 3 (p < 0.0001 vs. placebo) while bioavailable testosterone levels increased from 2.7 +/- 0.8 nmol/L at baseline to 5.4 +/- 1.7 nmol/L at month 3 (p < 0.0001 vs. placebo). Testosterone and biotestosterone levels peaked at month 3 and then declined by month 12 (though they remained significantly higher than baseline and greater than placebo). Estradiol levels decreased from 55.8 +/- 15.4 pmol/L at baseline to 42.2 +/- 13.6 pmol/L at month 3 and then remained stable (p < 0.0001). Body composition and strength did not change, nor did PSA, BPH symptoms, hematocrit or lipid levels.

CONCLUSIONS

Anastrozole administration normalized androgen production in older hypogonadal men and decreased estradiol production modestly. These alterations did not improve body composition or strength.

Insulin-like growth factor-I, regulating aromatase expression through steroidogenic factor 1, supports estrogen-dependent tumor Leydig cell proliferation

The aim of this study was to investigate the role of estrogens in Leydig cell tumor proliferation. We used R2C rat Leydig tumor cells and testicular samples from Fischer rats with a developed Leydig tumor. Both experimental models express high levels of aromatase and estrogen receptor alpha (ERalpha). Treatment with exogenous 17beta-estradiol (E(2)) induced proliferation of R2C cells and up-regulation of cell cycle regulators cyclin D1 and cyclin E, the expression of which was blocked by addition of antiestrogens. These observations led us to hypothesize an E(2)/ERalpha-dependent mechanism for Leydig cell tumor proliferation. In determining the molecular mechanism responsible for aromatase overexpression, we found that total and phosphorylated levels of transcription factors cyclic AMP-responsive element binding protein and steroidogenic factor 1 (SF-1) were higher in tumor samples. Moreover, we found that tumor Leydig cells produce high levels of insulin-like growth factor I (IGF-I), which increased aromatase mRNA, protein, and activity as a consequence of increased total and phosphorylated SF-1 levels. Specific inhibitors of IGF-I receptor, protein kinase C, and phosphatidylinositol 3-kinase determined a reduction in SF-1 expression and in IGF-I-dependent SF-1 recruitment to the aromatase PII promoter. The same inhibitors also inhibited aromatase expression and activity and, consequently, R2C cell proliferation. We can conclude that one of the molecular mechanisms determining Leydig cell tumorigenesis is an excessive estrogen production that stimulates a short autocrine loop determining cell proliferation. In addition, cell-produced IGF-I amplifies estrogen signaling through an SF-1-dependent up-regulation of aromatase expression. The identification of this molecular mechanism will be helpful in defining new therapeutic approaches for Leydig cell tumors.

Compartmentalized cAMP signalling in regulated exocytic processes in non-neuronal cells

Cyclic adenosine monophosphate (cAMP) is a central second messenger controlling a plethora of vital functions. Studies of cAMP dynamics in living cells have revealed markedly inhomogeneous concentrations of the second messenger in different compartments. Moreover, cAMP effectors such as cAMP-dependent protein kinase (PKA) and cAMP-activated GTP-exchange factors (Epacs) are tethered to specific cellular sites. Both the tailoring of cAMP concentrations, and the activities of cAMP-dependent signalling systems at specific cellular locations are prerequisites for most, if not all, cAMP-dependent processes. This review focuses on the role of compartmentalized cAMP signalling in exocytic processes in non-neuronal cells. Particularly, the insertion of aquaporin-2 into the plasma membrane of renal principal cells as an example for a cAMP-dependent exocytic process in a non-secretory cell type, renin secretion from juxtaglomerular cells as a cAMP-triggered exocytosis from an endocrine cell, insulin release from pancreatic beta-cells as a Ca2+-mediated and cAMP-potentiated exocytic processes in an endocrine cell, and cAMP- or Ca2+ -triggered H+ secretion from gastric parietal cells as an exocytic process in an exocrine cell are discussed. The selected examples of cAMP-regulated exocytic pathways are reviewed with regard to key proteins involved: adenylyl cyclases, phosphodiesterases, PKA, A kinase anchoring proteins (AKAPs) and Epacs.

Symptoms during the menopausal transition and early postmenopause and their relation to endocrine levels over time: observations from the Seattle Midlife Women's Health Study

OBJECTIVE

To determine whether hot flashes, depressed mood, sleep, cognitive and sexual symptoms correlate with urinary follicle-stimulating hormone (FSH), estrone (E(1)G), and testosterone (T) and with each other during the menopausal transition and early postmenopause (PM).

METHODS

Forty-one women who transitioned from middle or late transition stage to PM rated symptoms and provided monthly urine specimens as part of a longitudinal study of the menopausal transition.

RESULTS

Correlations between endocrine levels and symptom severity ratings over time revealed that hot flash severity was significantly and positively related to FSH and negatively to E1 G. Vaginal dryness was positively correlated with FSH and negatively correlated with T. Decreased sexual desire was correlated negatively with E(1)G levels. Forgetfulness was positively correlated with FSH; difficulty concentrating was negatively correlated with T. Severity of sleep symptoms and depressed mood were not correlated with E(1)G, FSH, or T. Correlations among the symptoms revealed that severity of hot flashes was associated with sleep disruption and forgetfulness. Depressed mood was correlated with sleep disruption, difficulty concentrating, and decreased sexual desire but not with hot flashes or vaginal dryness. Awakening during the night was correlated with decreased sexual desire and vaginal dryness, as well as hot flashes. Forgetfulness was associated with hot flashes and difficulty concentrating, whereas difficulty concentrating was associated with depressed mood and early awakening.

CONCLUSIONS

Symptoms many women experience during the menopausal transition and early PM are related to different endocrine levels (FSH, E(1)G, and T).

Expression of steroidogenic enzymes and synthesis of sex steroid hormones from DHEA in skeletal muscle of rats

The functional importance of sex steroid hormones (testosterone and estrogens), derived from extragonadal tissues, has recently gained significant appreciation. Circulating dehydroepiandrosterone (DHEA) is peripherally taken up and converted to testosterone by 3beta-hydroxysteroid dehydrogenase (HSD) and 17beta-HSD, and testosterone in turn is irreversibly converted to estrogens by aromatase cytochrome P-450 (P450arom). Although sex steroid hormones have been implicated in skeletal muscle regulation and adaptation, it is unclear whether skeletal muscles have a local steroidogenic enzymatic machinery capable of metabolizing circulating DHEA. Thus, here, we investigate whether the three key steroidogenic enzymes (3beta-HSD, 17beta-HSD, and P450arom) are present in the skeletal muscle and are capable of generating sex steroid hormones. Consistent with our hypothesis, the present study demonstrates mRNA and protein expression of these enzymes in the skeletal muscle cells of rats both in vivo and in culture (in vitro). Importantly, we also show an intracellular formation of testosterone and estradiol from DHEA or testosterone in cultured muscle cells in a dose-dependent manner. These findings are novel and important in that they provide the first evidence showing that skeletal muscles are capable of locally synthesizing sex steroid hormones from circulating DHEA or testosterone.

Involvement of protein kinase C and cyclic adenosine 3',5'-monophosphate-dependent kinase in steroidogenic acute regulatory protein expression and steroid biosynthesis in Leydig cells

This study investigated the roles of the protein kinase C (PKC) and protein kinase A (PKA) pathways in regulating constitutive steroidogenesis and steroidogenic acute regulatory (STAR; herein designated by its common name, StAR) protein in R2C Leydig tumor cells. Inhibition of PKC and phospholipase C resulted in significant decreases in steroid production, phosphorylation of cAMP-responsive element binding (CREB) protein, and Star gene transcription under basal conditions in R2C cells. These observations were corroborated in MA-10 and mLTC-1 Leydig tumor cell lines, in which activation of PKC by phorbol-12-myristate-13-acetate (PMA, 10 nM) increased CREB phosphorylation and total StAR (tot-StAR) protein expression. However, induction of StAR protein by PMA did not result in the expected concomitant increase in steroids because PKC failed to phosphorylate StAR, the biologically active form of the protein. However, in conjunction with PMA, minor increases in PKA activity using submaximal doses of (Bu)2cAMP (0.05-0.1 mM; a concentration range insufficient for induction of StAR), were able to stimulate dramatic increases in both phospho-StAR (P-StAR) and steroid production. Human chorionic gonadotropin stimulation also resulted in a further enhancement in P-StAR and progesterone production when added to PMA-treated MA-10 cells. Similar results for tot-StAR and P-StAR expression were observed in primary cultures of immature rat Leydig cells treated with PMA and submaximal doses of (Bu)2cAMP. In summary, the present study demonstrates that basal activities of both PKC and PKA play important roles in the constitutive steroidogenic characteristics of R2C cells. This study also demonstrates for the first time a role for PMA-induced PKC in StAR protein regulation and the requirement for submaximal doses of cAMP to produce steroids in Leydig cells.

Effects of leaf extract of Stephania hernandifolia on testicular gametogenesis and androgenesis in albino rats: a dose-dependent response study

The present study was undertaken to evaluate the dose-dependent effects of a leaf extract of Stephania hernandifolia on testicular activities in albino rats. Whether this leaf extract has any toxic effect on metabolic organs or on the liver or kidney was studied. Adult male Wistar rats, maintained under standard laboratory conditions, were forcefully fed with the aqueous extract of these leaves at the dose of 2 g or 4 g of leaves/mL distilled water/100 g body weight/day for 28 days. All the animals, along with vehicle-treated controls, were killed on the Day 29 of the experiment. Treatment with this leaf extract at both doses resulted in significant reduction in relative weight in the testis, the seminal vesicles, the prostate, and the epididymis without any significant change in the liver and kidney weight in comparison to control. Activities of testicular steroidogenic key enzymes and plasma testosterone level were decreased significantly, along with a significant reduction in the number of germ cells at stage VII of the spermatogenic cycle and in the seminiferous tubular diameter in both treated groups in comparison to control. Activities of glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, acid phosphatase, and alkaline phosphatase were not altered significantly in the liver and kidney in both treated groups compared with controls. We concluded that treatment with an aqueous extract of leaves resulted in diminution in the activities of testicular androgenic key enzymes and plasma level of testosterone along with inhibition of spermatogenesis without any induction of hepatic and renal toxicity.

The mechanism for lindane-induced inhibition of steroidogenesis in cultured rat Leydig cells

The in vitro effect of the gamma-isomer of hexachlorocyclohexane, lindane, on rat Leydig cell steroidogenesis was studied. Leydig cells from mature male rats were incubated with human chorionic gonadotropin (hCG, 1 IU) for 3 h at 34 degrees C in the presence of different doses of lindane (2-200 microg/ml; 2-200 ppm). Results demonstrate that lindane produces a dose-dependent inhibition of testosterone production in hCG-stimulated Leydig cells. The decreased testosterone synthesis was accompanied with a half-reduced LH/hCG receptor number without any modification in the K(d) value. In addition, lindane also decreased cAMP production. These effects were not due to a detrimental action of lindane on cell viability. Results of this study demonstrate a direct inhibitory action of lindane on testicular steroidogenesis, at least in part, through a reduction in the classical second messenger production involved in this pathway.

Regulation of steroidogenic enzymes and a novel testicular RNA helicase

Luteinizing hormone (LH) supports steroidogenesis and maintains testicular and ovarian function. Mediators of LH action exert homologous regulation of membrane receptors, steroidogenic enzymes and other regulatable genes of the Leydig cell (LC). Androgen and estrogen induced by LH could act through its cognate receptors in the LC to regulate gene expression. Although androgens are unquestionable essential for spermatogenesis and presumably exert their heterologous action through androgen receptors present in the Sertoli its regulatory mechanism in germinal cell maturation is far from clear. In contrast to physiological concentrations of gonadotropins which maintain the steroidogenic functions and LH and prolactin receptors in the gonads, high concentrations of gonadotropin (hCG) cause receptor down-regulation and desensitization of steroidogenic enzymes of the LCs in vivo (3beta-hydroxysteroid dehydrogenase types I and II, 17alpha-hydroxylase/17,20 lyase, and 17beta-hydroxysteroid dehydrogenase type III [17beta-HSD]). In addition, 17beta-HSD is regulated by compartmentalized endogenous glucose/ATP. The attenuation of steroidogenesis which results from receptor mediated activation by cognate hormone, but is independent of the subsequent phase of receptor down-regulation, is due to changes at the transcriptional level. Among the candidates affecting this regulation are active steroid metabolites (direct or indirect of steroids and other mediator(s) i.e. cAMP, putative transcription factors induced by LH action). Differential display assay revealed another gene which is transcriptionally regulated by gonadotropin termed GRTH (Gonadotropin Regulated Testicular Helicase). GRTH is a novel member of the DEAD-box family of RNA helicases, and is specifically expressed in LCs and meiotic LC of the testis. It is markedly up-regulated by hCG via cAMP-induced androgen formation in LCs at doses that cause down-regulation of receptors and steroidogenic enzymes. GRTH functions as a translational activator. Androgen produced by gonadotropin stimulation exerts intracrine/autocrine actions on GRTH, and also could influence transcription within the seminiferous tubule. GRTH may contribute to the control of steroidogenesis, including the restoration of down regulated cellular functions, and in the paracrine regulation of androgen dependent gene(s) involved in the meiotic process, and could thus have a crucial role in spermatogenesis.

Role of cytochrome P450c17 in polycystic ovary syndrome

The hyperandrogenism of polycystic ovary syndrome (PCOS) appears to be due to dysregulation of steroidogenesis within the ovaries and adrenal glands. P450c17 is the key enzyme that regulates androgen synthesis. It is the only enzyme known to have the capacity to convert C21-precursors to the androgen pre-hormones, the 17-ketosteroids. It is a single enzyme with two activities, 17-hydroxylase and 17,20-lyase. Thus, its regulation is a significant factor in the expression of hyperandrogenism. Androgen secretion is LH-dependent in the ovary and ACTH-dependent in the adrenal glands. The androgenic response to each of these tropic hormones seems to be modulated by intra-ovarian or intra-adrenal autocrine and paracrine mechanisms. This modulation serves to regulate steroid hormone secretion in tissue-specific ways. Insulin, IGFs and inhibin are among the many growth factors capable of augmenting the response to LH and ACTH. The insulin/IGF system stimulates P450c17 mRNA expression and activities in the ovaries and adrenal glands. An integrating link between insulin resistance and hyperandrogenemia may be serine phosphorylation, which inhibits activity of the insulin receptor and promotes the 17,20-lyase activity of P450c17. However, it must be kept in mind that there is some evidence for the existence of P450c17-independent pathways of androgen biosynthesis.

Characterization and regulation of prolactin receptors in MA-10 Leydig cells

The aim of this study is to further characterize the prolactin receptors (PRL-R) previously reported in the murine Leydig tumor MA-10 cell line, as well as to study their homologous and heterologous regulation. Two forms of PRL-R, a high and a low molecular weight form, were revealed by studies of covalent crosslinking of 125I-human GH to cultured MA-10 cells or cell membranes and immunoprecipitation of the solubilized PRL-R complexes with polyclonal anti PRL-R antibody, followed by SDS-PAGE and autoradiography. The long form had a molecular weight of 101 kDa and was predominant when the study was performed in the presence of protease inhibitors. The short form, with a molecular weight of 39 kDa, appeared, at least in part, to be a proteolytic product of the longer form. The same size forms of PRL-R were detected by crosslinking studies in the parental C57BL/6 mouse testicular Leydig cells, indicating the physiological relevance of the MA-10 cell model to the study of Leydig cell PRL-R. Homologous down-regulation of PRL-R was demonstrated in cultured MA-10 cells exposed for 24 h to increasing concentrations of PRL. In contrast, heterologous, 3 5-fold up-regulation of PRL-R was induced by various cAMP-elevating agents, including 8-bromo-cAMP (10(-4) -10(-3) M), dibutyryl cAMP (3 x 10(-3) M) and cholera toxin (1-10 ng/ml), although not by hCG (up to 100 ng/ml). This up-regulatory effect was apparently the result of a change in affinity, since cholera toxin caused a 2.4-fold increase in PRL-R affinity, with no change in the number of binding sites. In summary, these studies provide further evidence that MA-10 Leydig cells can serve as a physiologically relevant model for the study of PRL and PRL-R interactions, both at the functional level, as shown in our previous study, and at the structural and regulatory levels as shown in the current study.

Progesterone can participate in down-regulation of the luteinizing hormone receptor gene expression and function in cultured murine Leydig cells

The intratesticular concentration of progesterone (P) rises up to the micromolar range during high-dose luteinizing hormone (LH)/hCG stimulation. The aim of this study was to examine whether P is involved in the concomitant down-regulation of the LH receptor (R) function. The effects were tested in a mouse Leydig tumor cell line (mLTC-1) and in Percoll-purified adult mouse Leydig cells. Pre-incubation of the mLTC-1 cells for 48 h with P (1-10 micromol/l) decreased in dose-dependent fashion their specific binding of [125I]iodo-hCG as well as the hCG-induced cAMP production (down to 65 and 40% respectively, of controls, P < 0.01). Similar effect of P on hCG-induced cAMP production was observed in adult mouse Leydig cells following a 24 h incubation in the presence of P (0.3-10 micromol/l). In addition, P treatment significantly inhibited the expression of a transiently transfected murine LHR promoter (715 or 950 bp of the 5' untranslated region)-luciferase fusion constructs in mLTC-1 cells (down to 50% of control, P < 0.01). In accordance, a 6-12 h culture in the presence of 5-10 micromol/l of P showed significant down-regulatory effects on the steady state levels of LHR-mRNA in mLTC-1 cells. These inhibitory effects of P on the LHR expression and function were mimicked by similar concentrations of cortisol, but not by testosterone or estradiol. Blocking the steroid synthesis of mLTC-1 cells with 86 micromol/l of aminoglutethimide (AMG) partially reversed the down-regulating effect of hCG on the LHR-mRNA. Moreover, a 24 h culture in the presence of AMG showed an up-regulating effect on expression of the LHR promoter-luciferase constructs, and including hCG (50 microg/l) in the culture medium enhanced this effect. Hence, in the absence of steroidogenesis, hCG up-regulates the LHR promoter expression. In conclusion, we present here a novel short-loop regulatory mechanism in murine Leydig cells where P exerts a negative effect on LHR expression and function. Since Leydig cell P production is dramatically increased during high-dose stimulation with LH/hCG, due to blockade of C21 steroid side chain cleavage, the present findings offer a function for this steroid in the LHR down-regulation.

A stereological study of the different cell populations in chicken testes treated with follicle-stimulating hormone during embryonic development

Quantitative morphological methods were used to analyse the histomorphometric changes and variations in the number and size of cells from diverse cellular populations in testes of newly hatched chicks treated with follicle stimulating hormone (FSH) during embryonic development. The tissue was fixed and embedded in Epon and sections were morphometrically measured under light microscopy, using point counting for volume densities and the Floderus equation to determine numerical density. The average volume of the individual cell was determined by dividing the volume density by the numerical density. Results indicate that FSH administration causes an increase in the number of Sertoli cells and spermatogonia, as well as enlargement of the individual Sertoli cells leading consequently to an increase in the diameter and volume density of the testicular seminiferous tubules. Results also reveal an increase in the volume density of the interstitial cords of the Leydig cells, this expansion is due to the enlargement of the individual Leydig cells and not to an increase in their number, which remains constant. We conclude that testes of chick embryos are able to respond to FSH treatment, as revealed by the changes in the number and size of the cells conforming the diverse cellular populations of the testis. FSH treatment during embryonic development induces histomorphometric changes in both the interstitial tissue and seminiferous tubules, accelerating their growth and differentiation.

A Sertoli cell-secreted paracrine factor(s) stimulates proliferation and inhibits steroidogenesis of rat Leydig cells

Previous studies have shown that disruption or damage to the seminiferous tubules by radiation, antiandrogen, vitamin A deficiency or experimental cryptorchidism causes Leydig cell hypertrophy and hyperplasia, suggesting that Sertoli cells secrete a mitogenic factor(s) that stimulates Leydig cell proliferation. To study the possible paracrine regulation of Leydig cell proliferation by Sertoli cells, highly purified Leydig cells and Sertoli cells were co-cultured in a two-chambered co-culture system. Our results revealed that co-culture of immature rat Sertoli cells with Leydig cells stimulated Leydig cell DNA synthesis by 19-fold, increased cell number by about 3.9-fold and increased the labeling index from 0.5% to 15.8%. In addition to these changes, co-culture reduced Leydig cell testosterone formation and luteinizing hormone (LH) receptor levels, and dramatically altered the morphology of Leydig cells. The addition of concentrates from Sertoli cell conditioned medium (SCCM) mimicked these biological effects. The Leydig cell mitogenic activity in SCCM was trypsin sensitive and inactivated by boiling for 2 h, suggesting that it is a protein. However, it was resistant to acid and dithiothreitol. The molecular weight of this putative factor(s) is above 10 kDa. The responsiveness of Leydig cells to this mitogenic protein(s) decreased with age, whereas the secretion of this protein(s) by Sertoli cells in culture did not change with age. The addition of 10 ng/ml of follicle stimulating hormone (FSH) dramatically decreased the mitogenic activity in SCCM, indicating that the secretion of this mitogenic factor(s) is inhibited by FSH. This paracrine factor(s) may be as yet an unidentified testicular growth factor(s) because it differs in molecular weight, stability and other characteristics from all previously reported Sertoli cell-produced or expressed growth factors.

Serum testosterone concentration in response to exogenous GnRH does not predict service rates or pregnancy rates by yearling, performance tested, crossbred bulls

Ten bulls with a scrotal circumference of less than 30 cm at the end of growth performance testing, and 10 cohorts of the same age, size and breed type with a scrotal circumference greater than 30 cm were used to evaluate if testosterone response following GnRH administration could be used to test for fertility, for semen quality, and for specific pathologic testicular parenchymal changes. Serum testosterone concentrations were determined immediately before and 2 to 3 hours following intramuscular injection of 250 ug GnRH. Bulls were examined for breeding soundness, then fertility was tested in a breeding trial; testicular histology was assessed by determining the percentage of cross-sections of seminiferous tubules with no spermatocytes. The mean (+/-SEM) post-GnRH serum testosterone concentration for all bulls was 11.71 (+/-0.64) ng/ml. In order to examine for an association, the GnRH response was classified as above or below the mean for resultant serum testosterone concentration. The GnRH response classification was not related to the scrotal circumference, percentage of tubules devoid of spermatocytes, or percentage of progressively motile spermatozoa (P>0.10). The percentage of morphologically normal spermatozoa was significantly higher (P<0.05) in the bulls with a higher than mean testosterone secretion in response to GnRH injection. In the breeding trial, the percentage of heifers bred and the percentage of heifers pregnant (60 days post breeding) were not significantly different (P>0.10) between the 2 classifications of GnRH response. The GnRH response test was related to the percentage of morphologically normal spermatozoa but did not predict fertility of yearling bulls in this study.

The control of testicular androgen production in the goldfish: effects of activators of different intracellular signalling pathways

The putative roles of different signal transduction pathways in the regulation of testicular androgen production in goldfish were investigated. In addition to the role of the gonadotropin-adenylate cyclase pathway, which was studied using human chorionic gonadotropin and forskolin, we determined the effects of changes in intracellular calcium content and protein kinase C activation on androgen production using calcium ionophore A23187 and phorbol 12-myristate 13-acetate (PMA), respectively. Testis fragments incubated in vitro respond to hCG in a time- and dose-dependent manner with a resultant increase in the secretion of testosterone (T) and 11-ketotestosterone (11-KT). Although ineffective alone, PMA (400 nM) and A23187 (4000 nM) stimulate a small but significant increase (3-fold above basal) in T production. This response is minor compared to the up to 200-fold increase in T secretion observed in response to either hCG or forskolin. PMA (25-400 nM) alone and A23187 (250-4000 nM) alone inhibit the stimulatory actions of hCG on T production. Unlike PMA, the inactive phorbol 4 alpha-phorbol didecanoate, which does not activate PKC, had no effect on hCG-stimulated T production. PMA and A23187 did not influence the effects of forskolin on T production, suggesting that the compounds exert their effects prior to adenylate cyclase activation. In summary, the present studies suggest that in addition to the stimulatory actions of the adenylate cyclase second messenger system, changes in intracellular calcium content and protein kinase C activation may modulate testicular androgen production in the goldfish.

Effect of long-term administration of testosterone oenanthate on sympathetic neurotransmission to rat isolated seminal vesicles

1. The effects of prolonged administration of testosterone oenanthate (TE) on sympathetic neurotransmission to the rat isolated seminal vesicle were examined. 2. TE was administered at either 1.2 or 2.4 mg/kg subcutaneously (s.c.) thrice weekly for 8 weeks. A separate group of rats was administered the vehicle, sesame oil, 0.5 mL/kg, s.c. at the same regime and used as controls. TE administration increased plasma testosterone and dihydrotestosterone levels and seminal vesicle weights. TE 2.4 mg/kg suppressed fertility in male rats. 3. The mean -log EC50 values of adrenalin and noradrenaline in seminal vesicles from the control group were 5.30 (95% confidence limits: 5.14, 5.58; d.f. = 14) and 4.92 (95% confidence limits: 4.56, 5.49; d.f. = 14) respectively. Neither of these estimates were modified by TE administration. 4. The mean noradrenaline content (microgram/tissue) in seminal vesicles from control rats was 0.88 +/- 0.09 microgram/tissue. This did not change with TE treatment. Tissue noradrenaline concentration (microgram/g tissue), on the other hand, decreased by more than 50% in preparations from rats treated with TE. This was paralleled by a decrease in the density of catecholamine fluorescence. 5. Mean responses to field stimulation (20 pulses, 60 V dial setting, 2 ms, 1-70 Hz) appeared to decrease in preparations from TE treated groups; this decrease was, however, not statistically significant (P greater than 0.05; d.f. = 15). 6. It is concluded that prolonged administration of testosterone oenanthate to rats, at doses sufficient to suppress fertility, decreases the density of sympathetic innervation to the seminal vesicle by increasing smooth muscle mass. Treatment does not, however, modify the responses of this preparation to exogenously added catecholamines.

Insulin-like growth factor-I enhances luteinizing hormone binding to rat ovarian theca-interstitial cells

We tested the hypothesis that insulin-like growth factor-I (IGF-I) stimulates ovarian androgen production by increasing theca-interstitial cell luteinizing hormone (LH) binding affinity and/or binding capacity. We then investigated the role of transcriptional and translational events in mediating these actions of IGF-I. LH bound to saturable, high affinity binding sites on rat ovarian theca-interstitial cells. Preincubation with LH produced a decrease in LH binding capacity with no effect on LH binding affinity. Treatment with IGF-I, both in the absence and presence of LH, increased LH binding capacity 1.5- to 2-fold with no change in LH binding affinity. Androgen production was increased progressively by LH, suggesting that LH-stimulated steroidogenesis is not tightly coupled to LH receptor downregulation. IGF-I increased androgen synthesis in proportion to its upregulation of LH binding capacity. Transcriptional inhibition with dichlorobenzimidazole riboside inhibited the IGF-I-mediated increase in LH binding capacity but had no effect on androgen production. Translational inhibition with cycloheximide inhibited both the IGF-I-mediated increase in LH binding and stimulation of androgen synthesis. We conclude that IGF-I increases theca-interstitial cell LH binding capacity and reverses the LH-induced downregulation of LH binding sites. The enhancement of LH binding by IGF-I is compatible with transcriptional mediation whereas the effect of IGF-I on androgen synthesis appears to be mediated by a direct effect of the peptide on the translational process(es) involved in steroidogenesis.