Desensitization of the cAMP system in mouse Leydig cells by hCG, cholera toxin, dibutyryl cAMP and cAMP: localization of the 'lesion' to the guanine nucleotide regulatory protein-adenylate cyclase complex

The mechanism of hCG-induced desensitization of the cAMP system was studied in Percoll-purified mouse Leydig cells. Pretreatment of Leydig cells with hCG resulted in a time- and dose-dependent decrease in the capacity of hCG-induced cAMP formation. Maximal desensitization (approximately 90%) was induced by only partial prior stimulation. Desensitization, however, was not observed without a prior increase in cAMP or testosterone production. Pretreatment of the cells with N6,O2'-dibutyryl cAMP (DBcAMP) also induced a dose- and time-dependent densensitization. cAMP was only effective in the presence of the phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine (MIX). Cholera toxin desensitized the hormone-induced cAMP response as drastically as hCG. Cholera toxin was unable to reverse the refractory state induced by one of the agonists. hCG-induced desensitization was not associated with a loss in [125I]hCG binding or an increase in maximal phosphodiesterase activity, and appeared not to be dependent on protein synthesis. Membranes from hCG, cholera toxin of DBcAMP-desensitized cells showed an impaired adenylate cyclase activity in response to hCG, hCG plus beta-gamma-imidoguanosine 5'-triphosphate (GPPNP) and NaF. In conclusion, hCG-induced desensitization of the adenylate cyclase system in mouse Leydig cells can be mimicked by cholera toxin, DBcAMP and cAMP, indicating a cAMP-mediated process. The site of the 'lesion' has to be localized to the guanine nucleotide regulatory protein-adenylate cyclase complex rather than to its uncoupling from the hormone receptor.     

The many faces of testosterone

Testosterone is more than a “male sex hormone”. It is an important contributor to the robust metabolic functioning of multiple bodily systems. The abuse of anabolic steroids by athletes over the years has been one of the major detractors from the investigation and treatment of clinical states that could be caused by or related to male hypogonadism. The unwarranted fear that testosterone therapy would induce prostate cancer has also deterred physicians form pursuing more aggressively the possibility of hypogonadism in symptomatic male patients. In addition to these two mythologies, many physicians believe that testosterone is bad for the male heart. The classical anabolic agents, 17-alkylated steroids, are, indeed, potentially harmful to the liver, to insulin action to lipid metabolism. These substances, however, are not testosterone, which has none of these adverse effects. The current evidence, in fact, strongly suggests that testosterone may be cardioprotective. There is virtually no evidence to implicate testosterone as a cause of prostate cancer. It may exacerbate an existing prostate cancer, although the evidence is flimsy, but it does not likely cause the cancer in the first place. Testosterone has stimulatory effects on bones, muscles, erythropoietin, libido, mood and cognition centres in the brain, penile erection. It is reduced in metabolic syndrome and diabetes and therapy with testosterone in these conditions may provide amelioration by lowering LDL cholesterol, blood sugar, glycated hemoglobin and insulin resistance. The best measure is bio-available testosterone which is the fraction of testosterone not bound to sex hormone binding globulin. Several forms of testosterone administration are available making compliance much less of an issue with testosterone replacement therapy.     

Positive effects of short course androgen therapy on the neurodevelopmental outcome in boys with 47,XXY syndrome at 36 and 72 months of age

The effects of early androgen treatment on neurodevelopmental performance in pre‐pubertal boys with 47,XXY have not been well investigated. The influence of hormones on brain development in humans suggests that a positive effect on neurodevelopmental outcome in young boys with XXY may be plausible with hormone replacement therapy. The aim of the study was to investigate retrospectively if an early course of androgen treatment (three injections of testosterone enanthate, 25 mg, each) had an impact on specific domains of neurodevelopmental function in boys with 47,XXY at 36 and 72 months of age. One hundred one boys with a karyotype of 47,XXY had neurodevelopmental assessments. The retrospective chart review resulted in one group (n = 34) who had received androgen treatment during infancy and the second group was untreated (N = 67). Statistical analysis was completed to determine if there was a positive effect from treatment observed at 36 and at 72 months on multiple domains of development. There were significant differences in multiple cognitive domains in the group who received androgen treatment, including multiple measures of language, intellectual, and neuromotor skills. Improved function was observed in neurodevelopmental outcome in boys with 47,XXY at 36 and 72 months who had been treated with a short course of androgen treatment in infancy. Continued research is underway to expand our understanding of the relationship of androgen, brain function, and neurobehavioral and neurodevelopmental outcome in boys with 47,XXY. © 2013 Wiley Periodicals, Inc.     

Reproduction in male swamp wallabies (Wallabia bicolor): puberty and the effects of season

This study describes pubertal changes in testes and epididymides and seasonal changes in the adult male reproductive organs and plasma androgen concentrations of the swamp wallaby (Wallabia bicolor). Pre-pubescent males had testes with solid seminiferous cords and spermatogenesis only to the stage of gonocytes. Their epididymides had empty lumina along their entire length. The testes of three males undergoing puberty had some lumen formation and mitotic activity. Their epididymides were similar in appearance to those of adult males but were entirely devoid of any cells within the lumen of the duct. Three other pubescent males showed full lumen formation in the testes and spermatogenesis up to the elongating spermatid stage. Their epididymides were similar in appearance to those of adult males but with no spermatozoa in the duct. However, cells of testicular origin were found in the lumen of the duct in all regions suggesting that testicular fluids and immature germ cells shed into the rete testes flow through the seminiferous tubules into the epididymis before the release of mature testicular spermatozoa. The weights of testes and epididymides of adult males showed no change throughout the year but prostate weight and plasma androgen concentrations varied significantly with season, with maximums in spring and summer and minimums in winter. The volume fraction of Leydig cells and seminiferous tubules was significantly lower in winter than in summer; but, despite this, maturing spermatozoa were found in the testes throughout the year. Females in the area conceived year-round, suggesting that seasonal changes in the male reproductive tract did not prevent at least some males from breeding throughout the year.     

Human sperm express a functional androgen receptor: effects on PI3K/AKT pathway

BACKGROUND: Results from mice lacking the androgen receptor (AR) showed that it is critical for the proper development and function of the testes. The aim of this study was to investigate whether a functional AR is present in human sperm. METHODS: The expression of AR and its effects on sperm were evaluated by RT-PCR, Western Blot, Immunocytochemistry, PI3Kinase and DNA laddering assays. RESULTS: We showed in human sperm that AR is located at the head region. Dihydrotestosterone (DHT), in a dose-dependent manner, leads to the rapid phosphorylation of the AR on tyrosine, serine and threonine residues and this effect was reduced by the AR antagonist hydroxyflutamide (OH-Flut). The effects of AR were evaluated on the phosphoinositide-3 kinase/protein kinase B (PI3K/AKT) pathway. Specifically, 0.1 and 1 nM DHT stimulated PI3K activity, whereas 10 nM DHT decreased PI3K activity and levels of p-AKT S473 and p-AKT T308, p-BCL2, and enhanced phosphatase and tensin homologue (PTEN) phosphorylation. In addition, 10 nM DHT was able to induce the cleavage of caspases 8, 9 and 3 and cause DNA laddering, and these effects were reversed either by casodex or OHFlut. By using wortmannin, a specific PI3K inhibitor, the cleavage of caspase 3 was reproduced, confirming that in sperm the PI3K/AKT pathway is involved in caspase activation. CONCLUSIONS: Human sperm express a functional AR that have the ability to modulate the PI3K/AKT pathway, on the basis of androgen concentration.     

The excess in 2-5 mm follicles seen at ovarian ultrasonography is tightly associated to the follicular arrest of the polycystic ovary syndrome

BACKGROUND: We previously hypothesized that the excess of 2–5 mmfollicles seen at ovarian ultrasonography might be involvedin the follicular arrest (FA) of polycystic ovary syndrome (PCOS),independently from the main putative contributors of FA, namelyhyperandrogenism and hyperinsulinism. METHODS: A multivariate statistical analysis was applied retrospectivelyto clinical, biological and ultrasound data that were consecutivelycollected during 5 years in 457 patients with polycystic ovariesand in 188 age-matched non-hyperandrogenic and regularly cyclingcontrols without PCO at ultrasound. RESULTS: Stepwise discriminant analysis indicated that in PCOS the 2–5 mmfollicle number (FN) gave the strongest correlation to severityof the FA, followed by age and then by fasting insulin level.The other variables [waist circumference (WC), 6–9 mmFN, serum testosterone, FSH, LH and ovarian area] were rejectedby the analysis. Multiple linear regression indicated a significantand independent negative relationship between the 2–5and 6–9 mm FN in the PCOS (r = – 0.186, P <0.01) and control groups (r = – 0.281, P < 0.01). InPCOS only, the 6–9 mm FN was negatively and independentlyrelated to the WC (r = – 0.108, P < 0.05). CONCLUSIONS: The size of the 2–5 mm follicle pool is an independentand important contributor to the FA of PCOS. This result couldbe explained by an exaggerated physiological inhibitory effectfrom this pool on the terminal follicle growth. The metabolicderangement of PCOS that also contributes to the FA would actthrough a different mechanism.     

OPRM1 A118G and serum β-endorphin interact with sex and digit ratio (2D:4D) to influence risk and course of alcohol dependence

Activation of mesolimbic mu-opioid receptors by their endogenous ligand, β-endorphin, can mediate the rewarding effects of alcohol. However, there is conflicting evidence on the relationship between the mu-opioid receptor (OPRM1) A118G single nucleotide polymorphism (SNP) and alcohol dependence risk. Preclinical evidence suggests that sex and sex hormone-dependent prenatal brain organization may interact with the opioid system to influence alcohol drinking behavior. We genotyped 200 alcohol-dependent patients and 240 healthy individuals for the OPRM1 A118G SNP and measured serum β-endorphin level at recruitment and after acute withdrawal. We then determined the association between these factors and alcohol dependence risk and 24-month outcome in the context of both sex and second-to-fourth digit lengths ratio (2D:4D) – a biomarker of prenatal sex hormone levels. The OPRM1 A118G AA genotype associated with elevated risk of alcohol-related hospital readmission, more readmissions, and fewer days until first readmission in male patients only. After normalizing patient 2D:4D against control 2D:4D, we found that normalized 2D:4D ratios were lower in male 118G patients than male AA patients, suggesting prenatal androgens interact with OPRM1 to influence alcohol dependence risk. In addition, β-endorphin levels after acute withdrawal correlated negatively with withdrawal severity in females but not in males, which may indicate β-endorphin protects against withdrawal-induced stress in a sex-specific manner.