Induction of spermatogenesis by androgens in gonadotropin-deficient (hpg) mice

GnRH pulse generator activity in mouse models of polycystic ovary syndrome

One in ten women in their reproductive age suffer from polycystic ovary syndrome (PCOS) that, alongside subfertility and hyperandrogenism, typically presents with increased luteinizing hormone (LH) pulsatility. As such, it is suspected that the arcuate kisspeptin (ARNKISS) neurons that represent the GnRH pulse generator are dysfunctional in PCOS. We used here in vivo GCaMP fiber photometry and other approaches to examine the behavior of the GnRH pulse generator in two mouse models of PCOS. We began with the peripubertal androgen (PPA) mouse model of PCOS but found that it had a reduction in the frequency of ARNKISS neuron synchronization events (SEs) that drive LH pulses. Examining the prenatal androgen (PNA) model of PCOS, we observed highly variable patterns of pulse generator activity with no significant differences detected in ARNKISS neuron SEs, pulsatile LH secretion, or serum testosterone, estradiol, and progesterone concentrations. However, a machine learning approach identified that the ARNKISS neurons of acyclic PNA mice continued to exhibit cyclical patterns of activity similar to that of normal mice. The frequency of ARNKISS neuron SEs was significantly increased in algorithm-identified 'diestrous stage' PNA mice compared to controls. In addition, ARNKISS neurons exhibited reduced feedback suppression to progesterone in PNA mice and their gonadotrophs were also less sensitive to GnRH. These observations demonstrate the importance of understanding GnRH pulse generator activity in mouse models of PCOS. The existence of cyclical GnRH pulse generator activity in the acyclic PNA mouse indicates the presence of a complex phenotype with deficits at multiple levels of the hypothalamo-pituitary-gonadal axis.

Testosterone and Erythrocyte Lifespan

CONTEXT

Endogenous and exogenous androgens increase circulating erythrocytes and hemoglobin but their effects on erythrocyte lifespan is not known.

OBJECTIVE

To investigate androgen effects on immature and mature erythrocyte lifespan in humans and mice using novel nonradioactive minimally invasive methods.

DESIGN

Human erythrocyte lifespan was estimated using alveolar carbon monoxide concentration and blood hemoglobin in Levitt's formula in hypogonadal or transgender men before and up to 18 weeks after commencing testosterone (T) treatment. Erythrocyte lifespan was estimated in androgen receptor knockout and wild-type mice after T or DHT treatment of intact females or orchidectomized males using in vivo biotin labelling of erythrocyte surface epitopes for reticulocytes (Ter119+CD71+) and 2 markers of erythrocytes (CD45-, Ter119+CD71-) monitoring their blood disappearance rate by flow cytometry.

RESULTS

Before treatment, hypogonadal and transgender men had marked reduction in erythrocyte lifespan compared with controls. T treatment increased erythrocyte lifespan at 6 weeks but returned to pretreatment levels at 18 weeks, whereas serum T and blood hemoglobin were increased by T treatment remaining elevated at 18 weeks. In mice, T and DHT treatment had higher erythrocyte (but not reticulocyte) lifespan but neither orchidectomy nor androgen receptor inactivation significantly influenced erythrocyte or reticulocyte lifespan.

CONCLUSION

We conclude that hypogonadal men have reduced erythrocyte lifespan and acute androgen-induced increase in circulating erythrocyte lifespan may contribute to the well-known erythropoietic effects of androgens, but longer term effects require further investigation to determine how much they contribute to androgen-induced increases in circulating hemoglobin.

Investigating GABA Neuron-Specific Androgen Receptor Knockout in two Hyperandrogenic Models of PCOS

Androgen excess is a hallmark feature of polycystic ovary syndrome (PCOS), the most common form of anovulatory infertility. Clinical and preclinical evidence links developmental or chronic exposure to hyperandrogenism with programming and evoking the reproductive and metabolic traits of PCOS. While critical androgen targets remain to be determined, central GABAergic neurons are postulated to be involved. Here, we tested the hypothesis that androgen signaling in GABAergic neurons is critical in PCOS pathogenesis in 2 well-characterized hyperandrogenic mouse models of PCOS. Using cre-lox transgenics, GABA-specific androgen receptor knockout (GABARKO) mice were generated and exposed to either acute prenatal androgen excess (PNA) or chronic peripubertal androgen excess (PPA). Females were phenotyped for reproductive and metabolic features associated with each model and brains of PNA mice were assessed for elevated GABAergic input to gonadotropin-releasing hormone (GnRH) neurons. Reproductive and metabolic dysfunction induced by PPA, including acyclicity, absence of corpora lutea, obesity, adipocyte hypertrophy, and impaired glucose homeostasis, was not different between GABARKO and wild-type (WT) mice. In PNA mice, acyclicity remained in GABARKO mice while ovarian morphology and luteinizing hormone secretion was not significantly impacted by PNA or genotype. However, PNA predictably increased the density of putative GABAergic synapses to GnRH neurons in adult WT mice, and this PNA-induced plasticity was absent in GABARKO mice. Together, these findings suggest that while direct androgen signaling in GABA neurons is largely not required for the development of PCOS-like traits in androgenized models of PCOS, developmental programming of GnRH neuron innervation is dependent upon androgen signaling in GABA neurons.

Androgen receptor actions on AgRP neurons are not a major cause of reproductive and metabolic impairments in peripubertally androgenized mice

Excess levels of circulating androgens during prenatal or peripubertal development are an important cause of polycystic ovary syndrome (PCOS), with the brain being a key target. Approximately half of the women diagnosed with PCOS also experience metabolic syndrome; common features including obesity, insulin resistance and hyperinsulinemia. Although a large amount of clinical and preclinical evidence has confirmed this relationship between androgens and the reproductive and metabolic features of PCOS, the mechanisms by which androgens cause this dysregulation are unknown. Neuron-specific androgen receptor knockout alleviates some PCOS-like features in a peripubertal dihydrotestosterone (DHT) mouse model, but the specific neuronal populations mediating these effects are undefined. A candidate population is the agouti-related peptide (AgRP)-expressing neurons, which are important for both reproductive and metabolic function. We used a well-characterised peripubertal androgenized mouse model and Cre-loxP transgenics to investigate whether deleting androgen receptors specifically from AgRP neurons can alleviate the induced reproductive and metabolic dysregulation. Androgen receptors were co-expressed in 66% of AgRP neurons in control mice, but only in <2% of AgRP neurons in knockout mice. The number of AgRP neurons was not altered by the treatments. Only 20% of androgen receptor knockout mice showed rescue of DHT-induced androgen-induced anovulation and acyclicity. Furthermore, androgen receptor knockout did not rescue metabolic dysfunction (body weight, adiposity or glucose and insulin tolerance). While we cannot rule out developmental compensation in our model, these results suggest peripubertal androgen excess does not markedly influence Agrp expression and does not dysregulate reproductive and metabolic function through direct actions of androgens onto AgRP neurons.

Male germ cell proliferation and apoptosis in sexually immature meagre Argyrosomus regius (Asso, 1801) treated with recombinant follicle stimulating hormone

The meagre Argyrosomus regius (Asso, 1801) is a marine fish species that has an increasing aquaculture production in Europe. Lowering the age at maturity of hatchery-produced juveniles would support meagre aquaculture by reducing time between generations in selective breeding programs and reducing industrial costs for broodstock maintenance. The aim of this work was to assess the effects of a treatment with recombinant follicle stimulating hormone (rFsh), produced in ovarian cells of Chinese hamsters, on male germ cell proliferation and apoptosis in sexually immature meagre. The rFsh-treated fish had higher gonadosomatic index, larger seminiferous tubules, more abundant luminal spermatozoa, a lower density of anti-PCNA positive single A spermatogonia, a higher density of anti-PCNA positive spermatocysts and a lower incidence of germ cell apoptosis than control groups. The present study demonstrated the effectiveness of the produced rFsh in stimulating testis development and spermatogenesis in pre-pubertal meagre. Moreover, the rFsh treatment proved to be highly efficient in removing the apoptotic block of spermatogenesis observed in juvenile meagre, allowing spermatogonial survival and progress towards meiosis. The administration of rFsh did not stimulate spermatogonial self-renewal, a process whose control still needs to be elucidated.

Revisiting the gonadotropic regulation of mammalian spermatogenesis: evolving lessons during the past decade

Spermatogenesis is a multi-step process of male germ cell (Gc) division and differentiation which occurs in the seminiferous tubules of the testes under the regulation of gonadotropins - Follicle Stimulating Hormone (FSH) and Luteinising hormone (LH). It is a highly coordinated event regulated by the surrounding somatic testicular cells such as the Sertoli cells (Sc), Leydig cells (Lc), and Peritubular myoid cells (PTc). FSH targets Sc and supports the expansion and differentiation of pre-meiotic Gc, whereas, LH operates via Lc to produce Testosterone (T), the testicular androgen. T acts on all somatic cells e.g.- Lc, PTc and Sc, and promotes the blood-testis barrier (BTB) formation, completion of Gc meiosis, and spermiation. Studies with hypophysectomised or chemically ablated animal models and hypogonadal (hpg) mice supplemented with gonadotropins to genetically manipulated mouse models have revealed the selective and synergistic role(s) of hormones in regulating male fertility. We here have briefly summarized the present concept of hormonal control of spermatogenesis in rodents and primates. We also have highlighted some of the key critical questions yet to be answered in the field of male reproductive health which might have potential implications for infertility and contraceptive research in the future.

Declining muscle NAD+ in a hyperandrogenism PCOS mouse model: Possible role in metabolic dysregulation

Polycystic ovary syndrome (PCOS) is a common endocrine disorder, defined by reproductive and endocrine abnormalities, with metabolic dysregulation including obesity, insulin resistance and hepatic steatosis. Recently, it was found that skeletal muscle insulin sensitivity could be improved in obese, post-menopausal, pre-diabetic women through treatment with nicotinamide mononucleotide (NMN), a precursor to the prominent redox cofactor nicotinamide adenine dinucleotide (NAD+). Given that PCOS patients have a similar endocrine profile to these patients, we hypothesised that declining NAD levels in muscle might play a role in the pathogenesis of the metabolic syndrome associated with PCOS, and that this could be normalized through NMN treatment. Here, we tested the impact of NMN treatment on the metabolic syndrome of the dihydrotestosterone (DHT) induced mouse model of PCOS. We observed lower NAD levels in the muscle of PCOS mice, which was normalized by NMN treatment. PCOS mice were hyperinsulinaemic, resulting in increased adiposity and hepatic lipid deposition. Strikingly, NMN treatment completely normalized these aspects of metabolic dysfunction. We propose that addressing the decline in skeletal muscle NAD levels associated with PCOS can normalize insulin sensitivity, preventing compensatory hyperinsulinaemia, which drives obesity and hepatic lipid deposition, though we cannot discount an impact of NMN on other tissues to mediate these effects. These findings support further investigation into NMN treatment as a new therapy for normalizing the aberrant metabolic features of PCOS.

Metformin alleviates the dysregulated testicular steroidogenesis and spermatogenesis induced by carbimazole in levothyroxine-primed rats

Most of the published experiments about carbimazole (CMZ)-induced testicular injury are constructed in normal healthy animals, which lakes the translational identification. Despite metformin (MET) having advantageous effects on injured testicles, its impact on thyroid function is arguable. In the current levothyroxine (LT4)/CMZ model, Wistar rats were primed by LT4 for sixty days. CMZ was then given individually or simultaneously with different doses of MET, 100, 200, and 400 mg, daily for thirty days. Serum was assessed for thyroid profile panel, sex hormones, and gonadotropin levels. Testicular tissues were examined for steroidogenesis, spermatogenesis, inflammation, and apoptosis. Histopathology of thyroid and testes were examined, besides thyroidal nuclear factor (NF)-kB expression. MET in a dose-response manner improved the LT4/CMZ-induced testicular toxicity by increasing the steroidogenic acute regulatory protein (StAR), and 17-β-hydroxysteroid dehydrogenase (17βHSD) activities, the proliferating cell nuclear antigen (PCNA), sperm count and motility, sex hormones, and gonadotropin levels. MET-400 mg markedly decreased the elevated NF-kB expressions, tumour necrosis factor (TNF)-α, caspase-3, and BAX, and increased BCL-2. LT4/CMZ could be used as translational animal modelling. MET displayed a dose-dependent ameliorative effect on the LT4/CMZ model without significant harmful effects on thyroid functions. MET-testicular protective roles in diabetics with thyroidal diseases should be explored.

Androgen signaling in adipose tissue, but less likely skeletal muscle, mediates development of metabolic traits in a PCOS mouse model

Polycystic ovary syndrome (PCOS) is a common, multifactorial disorder characterized by endocrine, reproductive, and metabolic dysfunction. As the etiology of PCOS is unknown, there is no cure and symptom-oriented treatments are suboptimal. Hyperandrogenism is a key diagnostic trait, and evidence suggests that androgen receptor (AR)-mediated actions are critical to PCOS pathogenesis. However, the key AR target sites involved remain to be fully defined. Adipocyte and muscle dysfunction are proposed as important sites involved in the manifestation of PCOS traits. We investigated the role of AR signaling in white adipose tissue (WAT), brown adipose tissue (BAT), and skeletal muscle in the development of PCOS in a hyperandrogenic PCOS mouse model. As expected, dihydrotestosterone (DHT) exposure induced key reproductive and metabolic PCOS traits in wild-type (WT) females. Transplantation of AR-insensitive (AR^-/-) WAT or BAT from AR knockout females (ARKO) into DHT-treated WT mice ameliorated some metabolic PCOS features, including increased body weight, adiposity, and adipocyte hypertrophy, but not reproductive PCOS traits. In contrast, DHT-treated ARKO female mice transplanted with AR-responsive (AR^+/+) WAT or BAT continued to resist developing PCOS traits. DHT-treated skeletal muscle-specific AR knockout females (SkMARKO) displayed a comparable phenotype with that of DHT-treated WT females, with full development of PCOS traits. Taken together, these findings infer that both WAT and BAT, but less likely skeletal muscle, are key sites of AR-mediated actions involved in the experimental pathogenesis of metabolic PCOS traits. These data further support targeting adipocyte AR-driven pathways in future research aimed at developing novel therapeutic interventions for PCOS.NEW & NOTEWORTHY Hyperandrogenism is a key feature in the pathogenesis of polycystic ovary syndrome (PCOS); however, the tissue sites of androgen receptor (AR) signaling are unclear. In this study, AR signaling in white and brown adipose tissue, but less likely in skeletal muscle, was found to be involved in the development of metabolic PCOS traits, highlighting the importance of androgen actions in adipose tissue and obesity in the manifestation of metabolic disturbances.

Human INHBB Gene Variant (c.1079T>C:p.Met360Thr) Alters Testis Germ Cell Content, but Does Not Impact Fertility in Mice

Testicular-derived inhibin B (α/β B dimers) acts in an endocrine manner to suppress pituitary production of follicle-stimulating hormone (FSH), by blocking the actions of activins (β A/B/β A/B dimers). Previously, we identified a homozygous genetic variant (c.1079T>C:p.Met360Thr) arising from uniparental disomy of chromosome 2 in the INHBB gene (β B-subunit of inhibin B and activin B) in a man suffering from infertility (azoospermia). In this study, we aimed to test the causality of the p.Met360Thr variant in INHBB and testis function. Here, we used CRISPR/Cas9 technology to generate InhbbM364T/M364T mice, where mouse INHBB p.Met364 corresponds with human p.Met360. Surprisingly, we found that the testes of male InhbbM364T/M364T mutant mice were significantly larger compared with those of aged-matched wildtype littermates at 12 and 24 weeks of age. This was attributed to a significant increase in Sertoli cell and round spermatid number and, consequently, seminiferous tubule area in InhbbM364T/M364T males compared to wildtype males. Despite this testis phenotype, male InhbbM364T/M364T mutant mice retained normal fertility. Serum hormone analyses, however, indicated that the InhbbM364T variant resulted in reduced circulating levels of activin B but did not affect FSH production. We also examined the effect of this p.Met360Thr and an additional INHBB variant (c.314C>T: p.Thr105Met) found in another infertile man on inhibin B and activin B in vitro biosynthesis. We found that both INHBB variants resulted in a significant disruption to activin B in vitro biosynthesis. Together, this analysis supports that INHBB variants that limit activin B production have consequences for testis composition in males.

A Prospective Study of Male Depression, Psychotropic Medication Use, and Fecundability

We examined the associations of male depression and psychotropic medication use with fecundability in a North American preconception cohort study (2013–2020). Men aged ≥21 years completed a baseline questionnaire with questions on history of diagnosed depression, the Major Depression Inventory (MDI), and psychotropic medication use. Pregnancy status was updated via bimonthly female follow-up questionnaires until pregnancy or 12 menstrual cycles, whichever occurred first. Analyses were restricted to 2,398 couples attempting conception for ≤6 menstrual cycles at entry. We fit proportional probabilities models to estimate fecundability ratios (FRs) and 95% confidence intervals (CIs), adjusting for age (male and female), education, (male and female), race/ethnicity, physical activity, alcohol intake, body mass index, smoking, and having previously impregnated a partner. Nearly 12% of participants reported a depression diagnosis; 90.6% had low depressive symptoms (MDI <20), 3.5% had mild symptoms (MDI: 20–24), 2.7% had moderate symptoms (MDI: 25–29), and 3.3% had severe symptoms (MDI: ≥30). A total of 8.8% of participants reported current use of psychotropic medications. History of depression was associated with slightly reduced fecundability, although this result was also reasonably compatible with chance (FR = 0.89; 95% CI: [0.76, 1.04]). FRs for mild, moderate, and severe compared with low depressive symptoms were 0.89 (95% CI: [0.66, 1.21]), 0.90 (95% CI: [0.62, 1.31]), and 0.88 (95% CI: [0.65, 1.20]), respectively. This indicates little evidence of a dose–response relationship for depressive symptoms with fecundability, although estimates were imprecise. Current psychotropic medication use mediated 44% of the association between depressive symptoms and fecundability.

Promoting action of vitamin E and black seed oil on reproductive hormones and organ histoarchitecture of Swiss albino mice

Background

Vitamin E and black seed oil are two powerful antioxidants with several health benefits.

Objective

The effect of vitamin E and black seed oil on reproductive performance of Swiss albino mice was studied.

Methods

A total of 80 (40 male and 40 female) mice of 25–28 days old were randomly divided into four groups viz., A, B, C and D consisting of 10 mice in each group. Mice from the group A served as vehicle control and received normal mice ration whereas mice from the group B, C and D received feed supplemented with either black seed oil (0.5 ml/kg), vitamin E (200 mg/kg) or combination of black seed oil (0.5 ml/kg) and vitamin E (200 mg/kg), respectively daily for 16 weeks. At the end point of the study, blood samples were collected and sera were separated for hormonal analysis. At the same time, mice were sacrificed and testes and ovaries were collected for histomorphological examination.

Results

In male mice, the level of testosterone increased significantly in mice receiving black seed oil only, whereas the thyroxin increased significantly in all treated groups when compared to the control mice. Histomorphological examination revealed a significant increase in the diameter of seminiferous tubules in male mice fed with either black seed oil or vitamin E or both. On the other hand, the oestradiol and thyroxin concentration in female mice showed no significant changes in both control and treated groups. However, ovaries of mice fed with black seed oil or vitamin E or both showed an increased number of the follicles of different stages than the control mice.

Conclusions

The findings highlighted the promoting action of vitamin E and black seed oil on reproductive functions of mice and that can be used to treat infertility in man and animals.

Improvement of Astragalin on Spermatogenesis in Oligoasthenozoospermia Mouse Induced by Cyclophosphamide

More than 40% of infertile men are diagnosed with oligoasthenozoospermia and the incidence is still rising, but the effective treatments are not been found until now. Astragalin, one of the main active ingredients in traditional Chinese medicine, may be effective in the treatment of oligoasthenozoospermia. This study investigated the pharmacological effects of astragalin for treatment of oligoasthenozoospermia in male mice, induced by cyclophosphamide (CTX). Male mice were intraperitoneally injected by CTX (50 mg/kg), and astragalin (30 mg/kg) was given via oral gavage once daily. RNA-seq analysis highlighted astragalin upregulated gene expression of anti-apoptosis (AKT1and BCL2-XL), cell proliferation (ETV1, MAPKAPK2, and RPS6KA5) and synthesis of testosterone (STAR, CYP11A1, and PRKACB), but downregulated gene expression of cell apoptosis (BAD, BCL-2, CASPASE9, and CASPASE3) in mouse testis. Astragalin also significantly reversed the reduction in body weight, reproductive organs index, and sperm parameters (sperm concentration, viability, and motility) induced by CTX, and restored testicular abnormal histopathologic morphology induced by CTX. Furthermore, astragalin dramatically rescued the gene expression related to spermatogenesis (AKT1, BCL-2, CASPASE9, CASPASE3, MAPKAPK2, RPS6KA5, STAR, and PRKACB), and increased the level of testosterone by improving related proteins (STAR, CYP11A1, PRKACB) for oligoasthenozoospermia induced by CTX. In conclusion, astragalin may be a potential beneficial agent for oligoasthenozoospermia by increasing the testosterone levels in testis.

Pathogenesis of Reproductive and Metabolic PCOS Traits in a Mouse Model

Polycystic ovary syndrome (PCOS) is a common and heterogeneous disorder; however, the etiology and pathogenesis of PCOS are poorly understood and current management is symptom-based. Defining the pathogenesis of PCOS traits is important for developing early PCOS detection markers and new treatment strategies. Hyperandrogenism is a defining characteristic of PCOS, and studies support a role for androgen-driven actions in the development of PCOS. Therefore, we aimed to determine the temporal pattern of development of PCOS features in a well-characterized dihydrotestosterone (DHT)-induced PCOS mouse model after 2, 4, and 8 weeks of DHT exposure. Following 2 weeks of treatment, DHT induced the key PCOS reproductive features of acyclicity, anovulation, and multifollicular ovaries as well as a decrease in large antral follicle health. DHT-treated mice displayed the metabolic PCOS characteristics of increased body weight and exhibited increased visceral adiposity after 8 weeks of DHT treatment. DHT treatment also led to an increase in circulating cholesterol after 2 weeks of exposure and had an overall effect on fasting glucose levels, but not triglycerides, aspartate transaminase (AST) and alanine transaminase (ALT) levels, or hepatic steatosis. These data reveal that in this experimental PCOS mouse model, acyclicity, anovulation, and increased body weight are early features of a developing PCOS phenotype whereas adiposity, impaired glucose tolerance, dyslipidemia, and hepatic steatosis are later developing features of PCOS. These findings provide insights into the likely sequence of PCOS trait development and support the addition of body weight criteria to the early diagnosis of PCOS.

Amelioration of sperm fertilizability, thyroid activity, oxidative stress, and inflammatory cytokines in rabbit bucks treated with phytogenic extracts

This study investigated the beneficial effect of phytogenic extracts on semen quality, reproductive hormones, thyroid activity, immunity, hepatic antioxidant activity, and fertility in rabbit bucks. We divided 70 bucks into seven groups (10 in each). Group 1 was fed a basal diet (control); groups 2, 3, and 4 were fed the control diet with 30, 60, and 90 mg/kg of turmeric, respectively; and groups 5, 6, and 7 were fed the control diet with 50, 75, and 100 mg/kg of garlic extract, respectively, for 8 weeks. Rectal and skin temperatures decreased, while follicle-stimulating hormone, luteinizing hormone, triiodothyronine, thyroxine, testosterone, immunoglobulin M, tumor necrosis factor-alpha, and interleukin-6 in blood serum and glutathione peroxidase in the liver increased in all groups (p < .05). Garlic extract (100 mg/kg diet) increased adenosine triphosphate and glutathione in the liver tissues. All treatments significantly increased net semen volume, percentages of progressive motility, livability, curled tail, and intact acrosomes of spermatozoa, sperm cell concentration, and outputs of total and motile spermatozoa, while significantly decreased percentage of sperm abnormality. In conclusion, dietary supplementation of turmeric or garlic extract can be used as a suitable tool for enhancing the hepatic antioxidant activity, immunity, and semen quality in rabbit bucks.

Hsa-miR-100-3p Controls the Proliferation, DNA Synthesis, and Apoptosis of Human Sertoli Cells by Binding to SGK3

Human Sertoli cell is required for completing normal spermatogenesis, and significantly, it has important applications in reproduction and regenerative medicine because of its great plasticity. Nevertheless, the molecular mechanisms underlying the fate decisions of human Sertoli cells remain to be clarified. Here, we have demonstrated the expression, function, and mechanism of Homo sapiens-microRNA (hsa-miR)-100-3p in human Sertoli cells. We revealed that miR-100-3p was expressed at a higher level in human Sertoli cells by 10% fetal bovine serum (FBS) than 0.5% FBS. MiR-100-3p mimics enhanced the DNA synthesis and the proliferation of human Sertoli cells, as indicated by 5-ethynyl-2′-deoxyuridine (EdU) and Cell Counting Kit-8 (CCK-8) assays. Flow cytometry showed that miR-100-3p mimics reduced the apoptosis of human Sertoli cells, and notably, we predicted and further identified serum/glucocorticoid regulated kinase family member 3 (SGK3) as a direct target of MiR-100-3p. SGK3 silencing increased the proliferation and decreased the apoptosis of human Sertoli cells, while SGK3 siRNA 3 assumed a similar role to miR-100-3p mimics in human Sertoli cells. Collectively, our study indicates that miR-100-3p regulates the fate decisions of human Sertoli cells by binding to SGK3. This study is of great significance, since it provides the novel epigenetic regulator for the proliferation and apoptosis of human Sertoli cells and it may offer a new clue for gene therapy of male infertility.

Neurokinin 3 Receptor Antagonism Ameliorates Key Metabolic Features in a Hyperandrogenic PCOS Mouse Model

Polycystic ovary syndrome (PCOS) is a prevalent endocrine condition characterized by a range of endocrine, reproductive, and metabolic abnormalities. At present, management of women with PCOS is suboptimal as treatment is only symptomatic. Clinical and experimental advances in our understanding of PCOS etiology support a pivotal role for androgen neuroendocrine actions in PCOS pathogenesis. Hyperandrogenism is a key PCOS trait and androgen actions play a role in regulating the kisspeptin-/neurokinin B-/dynorphin (KNDy) system. This study aimed to investigate if targeted antagonism of neurokinin B signaling through the neurokinin 3 receptor (NK3R) would reverse PCOS traits in a dihydrotestosterone (DHT)-induced mouse model of PCOS. After 3 months, DHT exposure induced key reproductive PCOS traits of cycle irregularity and ovulatory dysfunction, and PCOS-like metabolic traits including increased body weight; white and brown fat pad weights; fasting serum triglyceride and glucose levels, and blood glucose incremental area under the curve. Treatment with a NK3R antagonist (MLE4901) did not impact the observed reproductive defects. In contrast, following NK3R antagonist treatment, PCOS-like females displayed decreased total body weight, adiposity, and adipocyte hypertrophy, but increased respiratory exchange ratio, suggesting NK3R antagonism altered the metabolic status of the PCOS-like females. NK3R antagonism did not improve circulating serum triglyceride or fasted glucose levels. Collectively, these findings demonstrate that NK3R antagonism may be beneficial in the treatment of adverse metabolic features associated with PCOS and support neuroendocrine targeting in the development of novel therapeutic strategies for PCOS.

Slit/Robo signaling regulates Leydig cell steroidogenesis

BACKGROUND

First identified as a regulator of neuronal axon guidance, Slit/Robo signaling has since been implicated in additional physiologic and pathologic processes, such as angiogenesis, organogenesis and cancer progression. However, its roles in the regulation of testis function have been little explored.

METHODS

Immunohistochemistry and RT-qPCR analyses were performed to detect the expression of Slit/Robo signaling effectors in the adult mouse testis. To identify the roles and mechanisms of Slit/Robo signaling in the regulation of steroidogenesis, RT-qPCR, immunoblotting and hormone measurements were carried out using Leydig cells (primary cultures and the MA10 cell line) treated with exogenous SLIT ligands, and testes from Robo1-null mice.

RESULTS

Slit1, -2 and -3 and Robo1 and -2 expression was detected in the adult mouse testis, particularly in Leydig cells. In vitro treatment of Leydig cells with exogenous SLIT ligands led to a decrease in the expression of the steroidogenic genes Star, Cyp11a1, and Cyp17a1. SLIT2 treatment decreased the phosphorylation of the key steroidogenic gene regulator CREB, possibly in part by suppressing AKT activity. Furthermore, SLIT2 treatment reduced the responsiveness of MA10 cells to luteinizing hormone by decreasing the expression of Lhcgr. Consistent with these in vitro results, an increase in testicular Star mRNA levels and intra-testicular testosterone concentrations were found in Robo1-null mice. Finally, we showed that the expression of the Slit and Robo genes in Leydig cells is enhanced by testosterone treatment in vitro, by an AR-independent mechanism.

CONCLUSION

Taken together, these results suggest that Slit/Robo signaling represents a novel mechanism that regulates Leydig cell steroidogenesis. It may act in an autocrine/paracrine manner to mediate negative feedback by testosterone on its own synthesis. Video Abstract.

The role of gonadotrophins in gonocyte transformation during minipuberty

PURPOSE

Postnatal surge of gonadotrophins, Luteinizing hormone (LH) and Follicle-Stimulating hormone (FSH) known as minipuberty, is critical for gonocyte maturation into spermatogonial stem cells (SSC) in the testis. Gonadotrophins are essential for optimum fertility in men, but very little is known how they regulate germ cells during minipuberty. This study examined whether gonadotrophins play a role on gonocyte transformation in vivo.

METHODS

Testes from hypogonadal (hpg) mice and their wild type (WT) littermates (n = 6/group) were weighed, and processed in paraffin at postnatal days (D) 0, 3, 6 and 9. Mouse VASA homologue (germ cell marker), anti-Müllerian hormone (Sertoli cell marker) antibodies and DAPI (nuclei marker) were used for immunofluorescence followed by confocal imaging. Germ cells on or off basement membrane (BM) and Sertoli cells/tubule were counted using Image J and analyzed with GraphPad.

RESULTS

Comparing to WT littermates, there were significantly fewer germ cells on BM/tubule (p < 0.05) in D9 hpg mice, whereas there was no significant difference for germ cells off BM/tubule and Sertoli cells/tubule between littermates. However, testicular weight was significantly reduced in D3-D9 hpg mice comparing to WT littermates.

CONCLUSION

Gonadotrophin deficiency reduced D9 germ cells on BM indicating impaired gonocyte transformation into SSC. This suggests that gonadotrophins may mediate gonocyte transformation during minipuberty.

Defining the impact of dietary macronutrient balance on PCOS traits

Lifestyle, mainly dietary, interventions are first-line treatment for women with polycystic ovary syndrome (PCOS), but the optimal diet remains undefined. We combined a hyperandrogenized PCOS mouse model with a systematic macronutrient approach, to elucidate the impact of dietary macronutrients on the development of PCOS. We identify that an optimum dietary macronutrient balance of a low protein, medium carbohydrate and fat diet can ameliorate key PCOS reproductive traits. However, PCOS mice display a hindered ability for their metabolic system to respond to diet variations, and varying macronutrient balance did not have a beneficial effect on the development of metabolic PCOS traits. We reveal that PCOS traits in a hyperandrogenic PCOS mouse model are ameliorated selectively by diet, with reproductive traits displaying greater sensitivity than metabolic traits to dietary macronutrient balance. Hence, providing evidence to support the development of evidence-based dietary interventions as a promising strategy for the treatment of PCOS, especially reproductive traits.

Role of Antioxidant Natural Products in Management of Infertility: A Review of Their Medicinal Potential

Infertility, a couple's inability to conceive after one year of unprotected regular intercourse, is an important issue in the world. The use of natural products in the treatment of infertility has been considered as a possible alternative to conventional therapies. The present study aimed to investigate the effects and the mechanisms of various natural products on infertility. We collected articles regarding infertility and natural products using the research databases PubMed and Google Scholar. Several natural products possess antioxidant properties and androgenic activities on productive factors and hormones. Antioxidants are the first defense barrier against free radicals produced by oxidative stress (OS). They remove reactive oxygen stress (ROS), reducing insulin resistance, total cholesterol, fat accumulation, and cancer growth. Moreover, various natural products increase endometrial receptivity and fertility ability showing androgenic activities on productive factors and hormones. For example, Angelica keiskei powder and Astragalus mongholicus extract showed anti-infertility efficacies in males and females, respectively. On the other hand, adverse effects and acute toxicity of natural products were also reported. Tripterygium glycoside decreased fertility ability both in males and females. Results indicate that management of infertility with natural products could be beneficial with further clinical trials to evaluate the safety and effect.

Age and Genetic Background Modify Hybrid Male Sterility in House Mice

Hybrid male sterility (HMS) contributes to reproductive isolation commonly observed among house mouse (Mus musculus) subspecies, both in the wild and in laboratory crosses. Incompatibilities involving specific Prdm9 alleles and certain Chromosome (Chr) X genotypes are known determinants of fertility and HMS, and previous work in the field has demonstrated that genetic background modifies these two major loci. We constructed hybrids that have identical genotypes at Prdm9 and identical X chromosomes, but differ widely across the rest of the genome. In each case, we crossed female PWK/PhJ mice representative of the M. m. musculus subspecies to males from a classical inbred strain representative of M. m. domesticus: 129S1/SvImJ, A/J, C57BL/6J, or DBA/2J. We detected three distinct trajectories of fertility among the hybrids using breeding experiments. The PWK129S1 males were always infertile. PWKDBA2 males were fertile, despite their genotypes at the major HMS loci. We also observed age-dependent changes in fertility parameters across multiple genetic backgrounds. The PWKB6 and PWKAJ males were always infertile before 12 weeks and after 35 weeks. However, some PWKB6 and PWKAJ males were transiently fertile between 12 and 35 weeks. This observation could resolve previous contradictory reports about the fertility of PWKB6. Taken together, these results point to multiple segregating HMS modifier alleles, some of which have age-related modes of action. The ultimate identification of these alleles and their age-related mechanisms will advance understanding both of the genetic architecture of HMS and of how reproductive barriers are maintained between house mouse subspecies.

Histone H2A.Z is required for androgen receptor-mediated effects on fear memory

Epigenetic factors translate environmental signals into stable outcomes, but how they are influenced by regulators of plasticity remain unclear. We previously showed that androgen receptor overexpression inhibited fear memory in male mice and increased expression of the histone variant H2A.Z, a novel epigenetic regulator of memory. Here, we used conditional-inducible H2A.Z knockout mice to investigate how H2A.Z deletion influences androgenic regulation of fear memory. We showed that conditional inducible H2A.Z deletion blocked memory-enhancing effects of androgen depletion (induced by gonadectomy), and of pharmacological inhibition of the androgen receptor with flutamide. Similarly, H2A.Z deletion blocked the memory-reducing effects of DHT, and DHT treatment in cultured hippocampal neurons altered H2A.Z binding, suggesting that AR is an H2A.Z regulator in neurons. Overall, these data show that fear memory formation is regulated by interactions between sex hormones and epigenetic factors, which has implications for sex differences in fear-related disorders.

Testosterone Supplementation Rescues Spermatogenesis and In Vitro Fertilizing Ability of Sperm in Kiss1 Knockout Mice

Restoration of spermatogenesis and fertility is a major issue to be solved in male mammals with hypogonadotropic hypogonadism. Kiss1 knockout (KO) male mice are postulated to be a suitable animal model to investigate if hormonal replacement rescues spermatogenesis in mammals with this severe reproductive hormone deficiency, because KO mice replicate the hypothalamic disorder causing hypogonadism. The present study investigated whether testosterone supplementation was able to restore spermatogenesis and in vitro fertilization ability in Kiss1 KO mice. To this end, spermatogenesis, in vitro fertilization ability of Kiss1 KO sperm, and preimplantation development of wild-type embryos inseminated with Kiss1 KO sperm, were examined. The newly generated Kiss1 KO male mice showed infertility with cryptorchidism. Subcutaneous testosterone supplementation for 6 weeks restored plasma and intratesticular testosterone levels, elicited testicular descent, and induced complete spermatogenesis from spermatocytes to elongated spermatids in the testis, resulting in an increase in epididymal sperm number in testosterone-supplemented Kiss1 KO male mice. Epididymal sperm derived from the testosterone-supplemented Kiss1 KO mice showed normal in vitro fertilization ability, and the fertilized eggs showed normal preimplantation development, while the males failed to impregnate females. These results suggest that the failure of spermatogenesis in Kiss1 KO mice is mainly due to a lack of testosterone production, and that Kiss1 KO sperm are capable of fertilizing eggs if the animals receive the appropriate testosterone supplementation without local kisspeptin signaling in the testis and epididymis. Thus, testosterone supplementation would restore spermatogenesis of male mammals showing hypogonadotropic hypogonadism with genetic inactivation of the KISS1/Kiss1 gene.

Dihydrotestosterone (DHT) Enhances Wound Healing of Major Burn Injury by Accelerating Resolution of Inflammation in Mice

Androgens have been known to inhibit cutaneous wound healing in men and male mice. However, in children with major burn injuries, a synthetic androgen was reported clinically to improve wound healing. The aim of this study is to investigate the role of dihydrotestosterone (DHT) as a new therapeutic approach in treating major burn injury. In the present study, mice received systemic androgen treatment post major burn injury. Wound healing rate and body weight were monitored over 21 days. The serum level of inflammatory cytokines/chemokines were measured using multiplex immunoassays. In addition, splenocyte enumeration was performed by flow cytometry. Healing phases of inflammation, re-epithelialization, cell proliferation and collagen deposition were also examined. In results, DHT treated mice lost less weight and displayed accelerated wound healing but has no impact on hypermetabolism. Mice, after burn injury, displayed acute systemic inflammatory responses over 21 days. DHT treatment shortened the systemic inflammatory response with reduced splenic weight and monocyte numbers on day 14 and 21. DHT treatment also reduced wound infiltrating macrophage numbers. In conclusion, DHT treatment facilitates local wound healing by accelerating the resolution of inflammation, but not through alterations of post-burn hypermetabolic response.

Androgen Action in Adipose Tissue and the Brain are Key Mediators in the Development of PCOS Traits in a Mouse Model

Polycystic ovary syndrome (PCOS) is a complex disorder characterized by endocrine, reproductive, and metabolic abnormalities. Despite PCOS being the most common endocrinopathy affecting women of reproductive age, the etiology of PCOS is poorly understood, so there is no cure and symptomatic treatment is suboptimal. Hyperandrogenism is the most consistent feature observed in PCOS patients, and recently aberrant neuroendocrine signaling and adipose tissue function have been proposed as playing a role in the development of PCOS. To investigate the role of adipose tissue and the brain as key sites for androgen receptor (AR)-mediated development of PCOS, we combined a white and brown adipose and brain-specific AR knockout (AdBARKO) mouse model with a dihydrotestosterone (DHT)-induced mouse model of PCOS. As expected, in wildtype (WT) control females, DHT exposure induced the reproductive PCOS traits of cycle irregularity, ovulatory dysfunction, and reduced follicle health, whereas in AdBARKO females, DHT did not produce the reproductive features of PCOS. The metabolic PCOS characteristics of increased adiposity, adipocyte hypertrophy, and hepatic steatosis induced by DHT in WT females were not evident in DHT-treated AdBARKO females, which displayed normal white adipose tissue weight and no adipocyte hypertrophy or liver steatosis. Dihydrotestosterone treatment induced increased fasting glucose levels in both WT and AdBARKO females. These findings demonstrate that adipose tissue and the brain are key loci of androgen-mediated actions involved in the developmental origins of PCOS. These data support targeting adipocyte and neuroendocrine AR-driven pathways in the future development of novel therapeutic strategies for PCOS.

Establishing the lower limits of total serum testosterone among Chinese proven fertile men who received treatment of assisted reproductive technology

Testosterone (T) plays a crucial role in spermatogenesis because extremely low levels of intratesticular T lead to correspondingly low serum levels of total T (tT), severe disorders of spermatogenesis, and male sterility. However, there is little consensus on the lower limits of serum tT in proven fertile men undergoing assisted reproductive technology treatments in Chinese or other Asian populations. We aimed to establish the reference range of serum tT based on a population of 868 fertile Chinese men undergoing in vitro fertilization or intracytoplasmic sperm injection and embryo transfer (IVF/ICSI-ET) treatments. We defined a fertile man as having had a live baby with his partner as recorded in our IVF registration system. The lower limits of serum tT were established using a Siemens IMMULITE 2000 chemiluminescent system. The 1st, 2.5th, and 5th percentiles and their 95% confidence intervals (CIs) were 3.6 (95% CI: 2.7-4.1) nmol l-1, 4.3 (95% CI: 4.1-5.0) nmol l-1, and 5.6 (95% CI: 4.8-5.8) nmol l-1, respectively. Using the linear correlation of serum tT between the Siemens platform and a liquid chromatography-tandem mass spectrometry platform, the calculated lower limits of serum tT were also established for fertile Chinese men undergoing IVF/ICSI-ET treatments, which will benefit the clinical diagnosis and treatment of male infertility during such procedures.

Rate and Extent of Recovery from Reproductive and Cardiac Dysfunction Due to Androgen Abuse in Men

CONTEXT

Androgen abuse impairs male reproductive and cardiac function, but the rate, extent, and determinants of recovery are not understood.

OBJECTIVE

To investigate recovery of male reproductive and cardiac function after ceasing androgen intake in current and past androgen abusers compared with healthy non-users.

METHODS

Cross-sectional, observational study recruited via social media 41 current and 31 past users (≥3 months since last use, median 300 days since last use) with 21 healthy, eugonadal non-users. Each provided a history, examination, and serum and semen sample and underwent testicular ultrasound, body composition analysis, and cardiac function evaluation.

RESULTS

Current abusers had suppressed reproductive function and impaired cardiac systolic function and lipoprotein parameters compared with non- or past users. Past users did not differ from non-users, suggesting full recovery of suppressed reproductive and cardiac functions after ceasing androgen abuse, other than residual reduced testicular volume. Mean time to recovery was faster for reproductive hormones (anti-Mullerian hormone [AMH], 7.3 months; luteinizing hormone [LH], 10.7 months) than for sperm variables (output, 14.1 months) whereas spermatogenesis (serum follicle-stimulating hormone [FSH], inhibin B, inhibin) took longer. The duration of androgen abuse was the only other variable associated with slower recovery of sperm output (but not hormones).

CONCLUSION

Suppressed testicular and cardiac function due to androgen abuse is effectively fully reversible (apart from testis volume and serum sex hormone binding globulin) with recovery taking between 6 to 18 months after ceasing androgen intake with possible cumulative effects on spermatogenesis. Suppressed serum AMH, LH, and FSH represent convenient, useful, and underutilized markers of recovery from androgen abuse.

Androgens Stimulate EPC-Mediated Neovascularization and Are Associated with Increased Coronary Collateralization

Endothelial progenitor cells (EPCs) play a key role in neovascularization and have been linked to improved cardiovascular outcomes. Although there is a well-established inverse relationship between androgen levels and cardiovascular mortality in men, the role of androgens in EPC function is not fully understood. In this study, we investigated the effects of androgens on 2 subpopulations of EPCs, early EPCs (EEPCs) and late outgrowth EPCs (OECs), and their relationships with coronary collateralization. Early EPCs and OECs were isolated from the peripheral blood of young healthy men and treated with dihydrotestosterone (DHT) with or without androgen receptor (AR) antagonist, hydroxyflutamide, in vitro. Dihydrotestosterone treatment enhanced AR-mediated proliferation, migration, and tubulogenesis of EEPCs and OECs in a dose-dependent manner. Furthermore, DHT augmented EPC sensitivity to extracellular stimulation by vascular endothelial growth factor (VEGF) via increased surface VEGF receptor expression and AKT activation. In vivo, xenotransplantation of DHT pretreated human EPCs augmented blood flow recovery and angiogenesis in BALB/c nude male mice, compared to mice receiving untreated EPCs, following hindlimb ischemia. In particular, DHT pretreated human OECs exhibited higher reparative potential than EEPCs in augmenting postischemic blood flow recovery in mice. Furthermore, whole blood was collected from the coronary sinus of men with single vessel coronary artery disease (CAD) who underwent elective percutaneous intervention (n = 23). Coronary collateralization was assessed using the collateral flow index. Serum testosterone and EPC levels were measured. In men with CAD, circulating testosterone was positively associated with the extent of coronary collateralization and the levels of OECs. In conclusion, androgens enhance EPC function and promote neovascularization after ischemia in mice and are associated with coronary collateralization in men.

New frontiers in fertility preservation: a hypothesis on fertility optimization in men with hypergonadotrophic hypogonadism

Strategies exist that can mitigate the risk of causing iatrogenic infertility when men require testosterone replacement therapy (TRT). This article reviews the current medical therapies that preserve spermatogenesis when TRT is indicated. Furthermore, we highlight the re-emerging concept of hypothalamic-pituitary-gonadal (HPG) axis reset in hypergonadotrophic, hypogonadal infertile men who are planning sperm retrieval procedures. Finally, we present our hypothesis for a novel protocol to optimize hypergonadotrophic hypogonadal men before sperm extraction surgeries hormonally.

New insights of CYP1A in endogenous metabolism: a focus on single nucleotide polymorphisms and diseases

Cytochrome P450 1A (CYP1A), one of the major CYP subfamily in humans, not only metabolizes xenobiotics including clinical drugs and pollutants in the environment, but also mediates the biotransformation of important endogenous substances. In particular, some single nucleotide polymorphisms (SNPs) for CYP1A genes may affect the metabolic ability of endogenous substances, leading to some physiological or pathological changes in humans. This review first summarizes the metabolism of endogenous substances by CYP1A, and then introduces the research progress of CYP1A SNPs, especially the research related to human diseases. Finally, the relationship between SNPs and diseases is discussed. In addition, potential animal models for CYP1A gene editing are summarized. In conclusion, CYP1A plays an important role in maintaining the health in the body.

Freeze-Dried Royal Jelly Proteins Enhanced the Testicular Development and Spermatogenesis in Pubescent Male Mice

Simple Summary

Spermatogenesis and hormones secretions are serious life-threating and complicated process, which can be improve through science-based approaches. Royal jelly is a thick white milky fluid secreted by the hypopharyngeal and mandibular glands of young nurse worker bees (Apis mellifera) and used to feed their queen to expand their life. The results of the study revealed that, the growth performance of testis in exposed mice to freeze-dried Royal Jelly for 35 consecutive days were significantly enhanced in moderate dose among other treated doses. However, at Post Natal Days (PNDs 14 and PNDs 21), obviously changes were observed in histological examination of the testis while at PNDs-07 no major changes were observed. The Tunnel assay showed that, less apoptotic cells were detected in the testis of mice in high dose of freeze-dried RJ and oral administration of freeze-dried royal jelly can aggravate adverse effects via tempestuous on sexual hormone secretion at both PNDs 21 and PNDs 35 respectively.

Abstract

Spermatogenesis and hormones secretions are crucial endocrine and physiological process for maintaining the life. Royal Jelly (RJ) bioactive components are Major Royal Jelly Proteins (MRJPs), owing exceptional biological properties. However, the effects of RJ on pup’s testicular development during neonatal and pubertal period exposure hasn’t been adequately studied. The aim of the study was to detect neonatal sexual hormones concentration and histopathological changes on testicular development of the male progeny after oral exposure to freeze-dried RJ for 35 consecutive days. After mice give birth, male pups were collected together, separated by sex, and randomly standardized to seven (7) male pups per dam. Male pups were assigned to control diet (CON group), low dose RJ (L-RJ group) diet (control diet + 125 mg/kg/day RJ), moderate dose RJ (M-RJ group) diet (control diet + 250 mg/kg/day RJ) and high dose of RJ (H-RJ group) diet (control diet + 500 mg/kg/day RJ). After weaning, male pups were continuously fed with freeze-dried RJ until the age of PNDs 35. The results revealed that, oral M-RJ (250 mg/kg/day) administration significantly (p < 0.05) increased the testis weight, the diameter of seminiferous tubule and the height of seminiferous epithelium of offspring mice at PNDs 14. However, high-dose RJ (500 mg/kg/day) decreased the diameter of seminiferous tubule but increased the height of seminiferous epithelium of male offspring (p < 0.05) at the same time point. Furthermore, oral M-RJ treatment significantly (p < 0.05) increased the testis weight and spermatogenesis at PNDs 21. Whereas, oral H-RJ treatment significantly (p < 0.05) reduced the diameter of seminiferous tubule and the height of seminiferous epithelium at PNDs 21. At PNDs 35, oral M-RJ treatment increased the testis weight, the diameter of seminiferous tubule and the level of FSH. While, high-dose of RJ reduced testis weight and size (diameter of seminiferous tubule and height of seminiferous epithelium), ratio of apoptotic germ cells and incomplete spermatogenesis collectively. In addition, sexual hormone secretions (FSH, LH, E2) were decreased after RJs treatment (L-RJ, M-RJ, H-RJ) at PNDs 21 respectively. In conclusion, the results concluded that oral administration of low and moderate doses of RJ could enhance the development of testis at neonate period until pubescent, whereas unfavorable adverse effects induced by high dose of RJ might remain.

Endocrine and local signaling interact to regulate spermatogenesis in zebrafish: follicle-stimulating hormone, retinoic acid and androgens

Retinoic acid (RA) is crucial for mammalian spermatogonia differentiation, and stimulates Stra8 expression, a gene required for meiosis. Certain fish species, including zebrafish, have lost the stra8 gene. While RA still seems important for spermatogenesis in fish, it is not known which stage(s) respond to RA or whether its effects are integrated into the endocrine regulation of spermatogenesis. In zebrafish, RA promoted spermatogonia differentiation, supported androgen-stimulated meiosis, and reduced spermatocyte and spermatid apoptosis. Follicle-stimulating hormone (Fsh) stimulated RA production. Expressing a dominant-negative RA receptor variant in germ cells clearly disturbed spermatogenesis but meiosis and spermiogenesis still took place, although sperm quality was low in 6-month-old adults. This condition also activated Leydig cells. Three months later, spermatogenesis apparently had recovered, but doubling of testis weight demonstrated hypertrophy, apoptosis/DNA damage among spermatids was high and sperm quality remained low. We conclude that RA signaling is important for zebrafish spermatogenesis but is not of crucial relevance. As Fsh stimulates androgen and RA production, germ cell-mediated, RA-dependent reduction of Leydig cell activity may form a hitherto unknown intratesticular negative-feedback loop.

Importance of the Androgen Receptor Signaling in Gene Transactivation and Transrepression for Pubertal Maturation of the Testis

Androgens are key for pubertal development of the mammalian testis, a phenomenon that is tightly linked to Sertoli cell maturation. In this review, we discuss how androgen signaling affects Sertoli cell function and morphology by concomitantly inhibiting some processes and promoting others that contribute jointly to the completion of spermatogenesis. We focus on the molecular mechanisms that underlie anti-Müllerian hormone (AMH) inhibition by androgens at puberty, as well as on the role androgens have on Sertoli cell tight junction formation and maintenance and, consequently, on its effect on proper germ cell differentiation and meiotic onset during spermatogenesis.

Androgens sensitise mice to glucocorticoid-induced insulin resistance and fat accumulation

AIMS/HYPOTHESIS

Chronic glucocorticoid therapy causes insulin resistance, dyslipidaemia, abnormal fat accumulation, loss of muscle mass and osteoporosis. Here we describe a hitherto unknown sexual dimorphism in the metabolic response to chronic glucocorticoid exposure in mice. This led us to investigate whether glucocorticoid-induced insulin resistance and obesity were dependent on sex hormones.

METHODS

Male and female CD1 mice were treated for 4 weeks with supraphysiological doses (~250 μg/day) of corticosterone, the main glucocorticoid in rodents, or equivalent volume of vehicle (drinking water without corticosterone). To investigate the effects of sex hormones, a separate group of mice were either orchidectomised or ovariectomised prior to corticosterone treatment, with or without dihydrotestosterone replacement. Body composition was determined before and after corticosterone treatment, and insulin tolerance was assessed after 7 and 28 days of treatment. Adipocyte morphology was assessed in white and brown adipose tissues by immunohistochemistry, and fasting serum concentrations of NEFA, triacylglycerols, total cholesterol and free glycerol were measured using colorimetric assays. Obesity- and diabetes-related hormones were measured using multiplex assays, and RNA and protein expression in adipose tissues were measured by RT-PCR and immunoblotting, respectively.

RESULTS

Chronic corticosterone treatment led to insulin resistance, fasting hyperinsulinaemia, increased adiposity and dyslipidaemia in male, but not female mice. In males, orchidectomy improved baseline insulin sensitivity and attenuated corticosterone-induced insulin resistance, but did not prevent fat accumulation. In androgen-deficient mice (orchidectomised males, and intact and ovariectomised females) treated with dihydrotestosterone, corticosterone treatment led to insulin resistance and dyslipidaemia. In brown adipose tissue, androgens were required for corticosterone-induced intracellular lipid accumulation ('whitening'), and dihydrotestosterone specifically exacerbated corticosterone-induced accumulation of white adipose tissue by increasing adipocyte hypertrophy. Androgens also suppressed circulating adiponectin concentrations, but corticosterone-induced insulin resistance did not involve additional suppression of adiponectin levels. In white adipose tissue, androgens were required for induction of the glucocorticoid target gene Gilz (also known as Tsc22d3) by corticosterone.

CONCLUSIONS/INTERPRETATION

In mice, androgens potentiate the development of insulin resistance, fat accumulation and brown adipose tissue whitening following chronic glucocorticoid treatment.

Neonatal Estrogen Causes Irreversible Male Infertility via Specific Suppressive Action on Hypothalamic Kiss1 Neurons

Aberrant exposure to estrogen-like compounds during the critical developmental period may cause improper hypothalamic programming, thus resulting in reproductive dysfunction in adulthood in male mammals. Kisspeptin-neurokinin B-dynorphin A (KNDy) neurons in the arcuate nucleus (ARC) have been suggested to govern tonic GnRH/gonadotropin release to control reproduction in male mammals. In this study, we report that chronic exposure to supraphysiological levels of estrogen during the neonatal period caused an irreversible suppression of KNDy genes in the ARC, resulting in reproductive dysfunction in male rats. Daily estradiol benzoate (EB) administration from days 0 to 10 postpartum caused smaller seminiferous tubules, abnormal spermatogenesis, and a decrease in plasma testosterone in adult male rats. The neonatal EB treatment profoundly suppressed LH pulse and ARC KNDy gene expression at adulthood, but it failed to affect the number of GnRH gene-expressing cells in male rats. The EB treatment failed to affect gene expression of other neuropeptides, such as GHRH, proopiomelanocortin, and agouti-related protein in the ARC, suggesting that ARC KNDy neurons would be a specific target of neonatal estrogen to cause male reproductive dysfunction. Because LH secretory responses to kisspeptin challenge and GnRH expression were spared in male rats with the EB treatment, LH pulse suppression is most probably due to ARC KNDy deficiency. Taken together, the current study indicates that chronic exposure to estrogenic chemicals in the developing brain causes a defect of ARC KNDy neurons, resulting in an inhibition of pulsatile GnRH/LH release and the failure of spermatogenesis and steroidogenesis.

Androgens Ameliorate Impaired Ischemia-Induced Neovascularization Due to Aging in Male Mice

There is abundant evidence that low circulating testosterone levels in older men are associated with adverse cardiovascular outcomes; however, the direction of causality is unclear. Although there is burgeoning interest in the potential of androgen therapy in older men, the effect of androgens on cardiovascular regeneration in aging males remains poorly defined. We investigated the role of androgens in age-related impairment in ischemia-induced neovascularization. Castrated young (2 months) and old (24 months) male mice were subjected to unilateral hindlimb ischemia and treated with subdermal DHT or placebo Silastic implants. Blood flow recovery was enhanced by DHT treatment in young and old mice compared with age-matched placebo controls. DHT augmented angiogenesis in young mice and ameliorated age-related impairment in neovascularization in old mice. Administration of DHT was associated with increased hypoxia inducible factor-1α (HIF-1α) and stromal cell‒derived factor-1 expression in young mice, but not in old mice. In vitro, DHT-induced HIF-1α transcriptional activation was attenuated in fibroblasts from old mice. Interaction between androgen receptor (AR) and importins, key proteins that facilitate nuclear translocation of AR, was impaired with age. In contrast, DHT treatment stimulated the production and mobilization of Sca1+/CXCR4+ circulating progenitor cells in both young and old mice. DHT stimulated the migration and proangiogenic paracrine effect of ex vivo cultured bone marrow‒derived angiogenic cells from young and old mice. In conclusion, androgens ameliorated age-related impairment in ischemia-induced neovascularization. Although age-dependent dysfunction in androgen signaling attenuated some androgen effects on angiogenesis, provasculogenic effects of androgens were partially preserved with age.

Androgen receptor expression is required to ensure development of adult Leydig cells and to prevent development of steroidogenic cells with adrenal characteristics in the mouse testis

Background

The interstitium of the mouse testis contains Leydig cells and a small number of steroidogenic cells with adrenal characteristics which may be derived from the fetal adrenal during development or may be a normal subset of the developing fetal Leydig cells. Currently it is not known what regulates development and/or proliferation of this sub-population of steroidogenic cells in the mouse testis. Androgen receptors (AR) are essential for normal testicular function and in this study we have examined the role of the AR in regulating interstitial cell development.

Results

Using a mouse model which lacks gonadotropins and AR (hpg.ARKO), stimulation of luteinising hormone receptors in vivo with human chorionic gonadotropin (hCG) caused a marked increase in adrenal cell transcripts/protein in a group of testicular interstitial cells. hCG also induced testicular transcripts associated with basic steroidogenic function in these mice but had no effect on adult Leydig cell-specific transcript levels. In hpg mice with functional AR, treatment with hCG induced Leydig cell-specific function and had no effect on adrenal transcript levels. Examination of mice with cell-specific AR deletion and knockdown of AR in a mouse Leydig cell line suggests that AR in the Leydig cells are likely to regulate these effects.

Conclusions

This study shows that in the mouse the androgen receptor is required both to prevent development of testicular cells with adrenal characteristics and to ensure development of an adult Leydig cell phenotype.

Electronic supplementary material

The online version of this article (10.1186/s12861-019-0189-5) contains supplementary material, which is available to authorized users.

Androgen action augments ischemia-induced, bone marrow progenitor cell-mediated vasculogenesis

Bone marrow-derived progenitor cell-mediated vasculogenesis is a key process for vascular repair and regeneration. However, the role of androgens in the mechanism of ischemia-induced vasculogenesis remains unclear. In this study, a gender-mismatch murine bone marrow transplant model was used to allow tissue tracking of transplanted cells. Bone marrow from 2-month-old male mice was transplanted into irradiated age-matched female recipients. Following the transplantation, ovariectomized female recipients were subjected to unilateral hindlimb ischemia and immediately implanted with either dihydrotestosterone (DHT) or placebo pellets. Laser Doppler perfusion imaging revealed that DHT significantly augmented blood flow recovery, with increased capillary density compared to placebo-treated female recipient controls. Flow cytometry analysis showed that DHT modulated vasculogenesis by increasing Sca1+/CXC4+ progenitor cell production in bone marrow and spleen and enhancing cell mobilization in circulating blood following hindlimb ischemia. Bone marrow cell homing was examined by detecting expression levels of male-specific SRY gene in the ischemic female tissues. DHT treatment promoted bone marrow cell homing to ischemic tissue shown by significantly higher SRY expression compared to placebo-treated females as well as reduced apoptotic features in DHT-treated females, including increased Bcl-2 expression, reduced Bax levels and decreased TUNEL staining. In conclusion, the gender-mismatched bone marrow transplant study shows that androgens directly enhance bone marrow cell-mediated vasculogenesis that contributes to ischemia-induced neovascularization.

Circulating Testosterone as the Hormonal Basis of Sex Differences in Athletic Performance

Elite athletic competitions have separate male and female events due to men's physical advantages in strength, speed, and endurance so that a protected female category with objective entry criteria is required. Prior to puberty, there is no sex difference in circulating testosterone concentrations or athletic performance, but from puberty onward a clear sex difference in athletic performance emerges as circulating testosterone concentrations rise in men because testes produce 30 times more testosterone than before puberty with circulating testosterone exceeding 15-fold that of women at any age. There is a wide sex difference in circulating testosterone concentrations and a reproducible dose-response relationship between circulating testosterone and muscle mass and strength as well as circulating hemoglobin in both men and women. These dichotomies largely account for the sex differences in muscle mass and strength and circulating hemoglobin levels that result in at least an 8% to 12% ergogenic advantage in men. Suppression of elevated circulating testosterone of hyperandrogenic athletes results in negative effects on performance, which are reversed when suppression ceases. Based on the nonoverlapping, bimodal distribution of circulating testosterone concentration (measured by liquid chromatography-mass spectrometry)-and making an allowance for women with mild hyperandrogenism, notably women with polycystic ovary syndrome (who are overrepresented in elite athletics)-the appropriate eligibility criterion for female athletic events should be a circulating testosterone of <5.0 nmol/L. This would include all women other than those with untreated hyperandrogenic disorders of sexual development and noncompliant male-to-female transgender as well as testosterone-treated female-to-male transgender or androgen dopers.

Hormonal Regulation of Testicular Development in the Finless Porpoise Neophocaena asiaeorientalis sunameri: Preliminary Evidence from Testicular Histology and Immunohistochemistry

Yang Xiao, Ghulam Nabi, Jiwei Yang, Yujiang Hao, and Ding Wang (2018) Sex hormones play a crucial role in regulating testicular development and maintaining spermatogenesis in the male reproductive system. Knowledge of hormonal regulation in odontocetes is limited to captive species. In this study, the characteristics of hormonal regulation during the testicular development were assessed by histological and immunohistochemical methods in the East Asian finless porpoise (Neophocaena asiaeorientalis sunameri), native to the Chinese Yellow/Bohai Sea coast, China. The testes mass, seminiferous tubule cross section diameter, thickness of the tunica albuginea, and the level of testosterone (T) expression increased abruptly at the age of 3-3.5 years (body length 140-145 cm). However, the estradiol (E₂) expression level decreased with age after 3 years. Therefore, we inferred that the male East Asian finless porpoise (EAFP) > 3 years old (body length > 140 cm) could be classified as the age of puberty onset. Immuno-localization with T was only observed in the interstitial fluid of all animals at all ages. In contrast, a positive reaction for E₂ and its receptor could be observed in the Leydig, myoid, Sertoli, and germ cells at different developmental stages. T is presumed to maintain the tubular microenvironment for spermatogenesis while E₂ may directly regulate spermatogenesis at the level of germ cells. Our findings provide useful information for understanding reproductive status and hormonal regulation in the male EAFP.

MECHANISMS IN ENDOCRINOLOGY: Hormonal regulation of spermatogenesis: mutant mice challenging old paradigms

The two pituitary gonadotrophins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and in particular LH-stimulated high intratesticular testosterone (ITT) concentration, are considered crucial for spermatogenesis. We have revisited these concepts in genetically modified mice, one being the LH receptor (R)-knockout mouse (LuRKO), the other a transgenic mouse expressing in Sertoli cells a highly constitutively active mutated Fshr (Fshr-CAM). It was found that full spermatogenesis was induced by exogenous testosterone treatment in LuRKO mice at doses that restored ITT concentration to a level corresponding to the normal circulating testosterone level in WT mice, ≈5 nmol/L, which is 1.4% of the normal high ITT concentration. When hypogonadal LuRKO and Fshr-CAM mice were crossed, the double-mutant mice with strong FSH signaling, but minimal testosterone production, showed near-normal spermatogenesis, even when their residual androgen action was blocked with the strong antiandrogen flutamide. In conclusion, our findings challenge two dogmas of the hormonal regulation of male fertility: (1) high ITT concentration is not necessary for spermatogenesis and (2) strong FSH stimulation can maintain spermatogenesis without testosterone. These findings have clinical relevance for the development of hormonal male contraception and for the treatment of idiopathic oligozoospermia.

Conditional Deletion of FOXL2 and SMAD4 in Gonadotropes of Adult Mice Causes Isolated FSH Deficiency

The glycoprotein FSH, a product of pituitary gonadotrope cells, regulates ovarian follicle development in females and spermatogenesis in males. FSH is a heterodimer of the common α gonadotropin subunit and the hormone-specific FSHβ subunit (a product of the Fshb gene). Using a conditional knockout approach (Cre-lox), we previously demonstrated that Fshb expression in mice depends on the transcription factors forkhead box L2 (FOXL2) and SMAD4. Deletion of Foxl2 or Smad4 alone led to FSH deficiency, female subfertility, and oligozoospermia in males. Simultaneous deletion of the two genes yielded a greater suppression of FSH and female sterility. The Cre-driver used previously was first active during embryonic development. Therefore, it is unclear whether FOXL2 and SMAD4 play important roles in the development or adult function of gonadotropes, or both. To address this question, we developed a tamoxifen-inducible Cre-driver line, which enabled Foxl2 and Smad4 gene deletions in gonadotropes of adult mice. After tamoxifen treatment, females with previously demonstrated fertility exhibited profound reductions in FSH levels, arrested ovarian follicle development, and sterility. FSH levels were comparably reduced in males 1 or 2 months after treatment; however, spermatogenesis was unaffected. These data indicate that (1) FOXL2 and SMAD4 are necessary to maintain FSH synthesis in gonadotrope cells of adult mice, (2) FSH is essential for female reproduction but appears to be unnecessary for the maintenance of spermatogenesis in adult male mice, and (3) the inducible Cre-driver line developed here provides a powerful tool to interrogate gene function in gonadotrope cells of adult mice.

Testosterone Retention Mechanism in Sertoli Cells: A Biochemical Perspective

Mechanism(s) involved in regulating Intratesticular Testosterone levels (iT) have assumed importance in recent years, from the point of view of hormonal contraception. Contraceptives using Testosterone (T) in combination with Progestins (P), for more effective suppression of pituitary gonadotropins thereby iT, are not 100% effective in suppressing spermatogenesis in human males, likely due to pesrsistence of Intratesticular Dihydrotestosterone (iD) in poor-responders. Several lacunae pertaining to the mechanism of action of principal male hormone T during spermatogenesis remain to be resolved. Notably, the mechanism through which T brings about the stage-specific differentiation of germ cells lacking Androgen Receptors (AR). Testosterone is a highly anabolic steroid with a rapid tissue clearance rate. T is intratesticular substrate for synthesis of Dihydrotestosterone (DHT) and Estradiol (E2) involved in spermtaogenesis. Therefore, it is important to delineate the mechanism(s) for retention of iT, in order to understand regulation of its bioavailability in testis. In depth studies, pertaining to the role of androgen-binding protein(s) in sequestration, retention and bioavailability of T/DHT are required to understand male fertility regulation. The appropriate approach to overcome this lacuna would be development of mice lacking functional testicular Androgen-Binding Protein (ABPKO), but not deficient T/DHT, Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH), in order to understand its physiological functions. Insights gained about androgen retention mechanism(s) from the ABPKO murine model will be of immense help in improving the efficacy of male hormonal contraceptives and infertility management.

Reintroducing testosterone in the db/db mouse partially restores normal glucose metabolism and insulin resistance in a leptin-independent manner

BACKGROUND

Testosterone signals through the androgen receptor (AR) and AR knockout mice develop obesity, suggesting a functional association between AR and leptin signaling. Furthermore, physiological blood concentrations of testosterone have been found to inhibit the development of arteriosclerosis, obesity and diabetes. However, these findings have not been verified by testosterone replacement in animal models and whether or not testosterone acts directly by activating AR to enhance leptin signaling, or indirectly by its conversion into estrogen remains unclear. Therefore, we investigated the effect of exogenously supplemented testosterone on glucose and lipid metabolism.

METHODS

Four-week-old male leptin receptor-knockout db/db mice were used as controls for a model of obesity retaining low testosterone. Mice were divided into sham-operated, castrated, or castrated and testosterone-supplemented groups and fed a high-fat diet (HFD) for 2 weeks from 5 weeks of age. Testosterone concentrations, blood glucose, plasma insulin levels, and intraperitoneal glucose tolerance and insulin tolerance were measured. At 7 weeks, triglyceride and glycogen content were measured in the liver and muscle. Lipid accumulation in the liver and soleus muscle was determined by immunohistochemistry with Oil Red O. Statistical analyses were performed using the Student's t-test or ANOVA where applicable.

RESULTS

Lower testosterone levels in db/db mice compared with wild type (WT) db/+ mice were associated with glucose intolerance and fatty liver. Furthermore, castrated male db/db mice at 4 weeks of age progressively developed glucose intolerance accompanying a 15% increase in liver fat. Male mice fed a HFD had lower levels of testosterone compared with those fed a normal diet. We found that exogenous testosterone replacement injected subcutaneously into castrated male db/db mice alleviated the exacerbation of fatty liver and glucose intolerance, suggesting a leptin-independent mechanism. This mechanism is most likely mediated through gonadal axis suppression in this mouse model.

CONCLUSIONS

In summary, testosterone may use a novel pathway to complement leptin signaling to regulate glucose and lipid metabolism, and thus offers a new therapeutic target to treat metabolic disorders.