Gonadotrophin control of testicular germ cell development

Thiopurines exert harmful effects on spermatogenesis in Nudt15R138C knock-in mice

BACKGROUND

The association between thiopurine use and testicular reproductive functions remains unclear. In this study, we investigated whether thiopurines affect testicular functions based on the NUDT15 genotypes using Nudt15R138C knock-in mice.

METHODS

The male Nudt15R138C knock-in mice (9-12 weeks) were treated with mercaptopurine (MP: 0.5 mg/kg/day) for 4 or 12 weeks. To examine reversibility, some mice were maintained for a further 12 weeks under MP-free condition.

RESULTS

After MP treatment for 4 weeks, Nudt15R138C/R138C mice exhibited a significant reduction of testis weight compared to Nudt15+/+ mice and Nudt15+/R138C mice. The epithelial height and diameter of seminiferous tubules were significantly reduced in Nudt15R138C/R138C mice compared to Nudt15+/+ and Nudt15+/R138C mice. Apoptotic cells were significantly increased in Nudt15R138C/R138C mice, and most of apoptotic cells were spermatogonia. There were no significant changes in sperm counts and sperm morphology in MP-treated Nudt15R138C/R138C mice after 4-week MP treatment. On the other hand, after MP treatment for 12 weeks, the Nudt15+/R138C mice, but not Nudt15+/+ mice, exhibited a significant reduction in the testis weight and atrophic changes of seminiferous tubules, but these changes disappeared after 12-week rearing under MP-free condition. Despite a significant increase in abnormal sperm rate, there were no changes in the ability to conceive. No differences in serum levels of follicle-stimulating hormone or testosterone were observed between MP-treated Nudt15+/R138C and Nudt15+/+ mice after 12-week MP treatment.

CONCLUSIONS

Thiopurines exert harmful effects on testicular reproductive function according to host NUDT15 genotypes.

Reproductive hormones, organophosphate esters and semen quality: Exploring associations and mediation effects among men from an infertility clinic

Accumulating evidence indicates that organophosphate esters (OPEs) exposure may affect semen quality. As a crucial factor in male reproduction, reproductive hormones might be linked organophosphate esters (OPEs) exposure and semen quality. This study aimed to explore the mediating role of reproductive hormones on the association between OPEs exposure and semen quality. Five serum reproductive hormones, semen quality, and 16 urinary OPE metabolites were measured among 491 reproductive-aged men from a reproductive center. The associations of urinary OPE metabolites with reproductive hormones and semen quality were assessed using multivariable linear regression models, and the mediating role of reproductive hormones was evaluated by mediation analyses. We found that follicle stimulating hormone (FSH) was positively associated with diphenyl phosphate (DPHP) that in turn was negatively associated with sperm total count. In addition, inverse associations were exhibited between serum FSH and sperm concentration, sperm total count, total motility, and progressive motility (all Ptrend <0.05). Mediation analysis further showed that FSH mediated 13.7% of the inverse association of DPHP and sperm total count. Although further investigations are required, our results suggest that FSH was an intermediate mechanism in the associations between OPEs exposure and impaired semen quality.

Sex-dependent changes of hippocampal synaptic plasticity and cognitive performance in C57BL/6J mice exposed to neonatal repeated maternal separation

The repeated maternal separation (RMS) is a useful experimental model useful in rodents to study the long-term influence of early-life stress on brain neurophysiology. We here investigated the influence of RMS exposure on hippocampal inhibitory and excitatory synaptic transmission, long-term synaptic plasticity and the related potential alterations in learning and memory performance in adult male and female C57Bl/6J mice. Mice were separated daily from their dam for 360 min, from postnatal day 2 (PND2) to PND17, and experiments were performed at PND 60. Patch-clamp recordings in hippocampal CA1 pyramidal neurons revealed a significant enhancement of GABAergic miniature IPSC (mIPSC) frequency, and a decrease in the amplitude of glutamatergic mEPSCs in male mice exposed to RMS. Only a slight but significant reduction in the amplitude of GABAergic mIPSCs was observed in females exposed to RMS compared to the relative controls. A marked increase in long-term depression (LTD) at CA3-CA1 glutamatergic synapses and in the response to the CB1r agonist win55,212 were detected in RMS male, but not female mice. An impaired spatial memory and a reduced preference for novelty was observed in males exposed to RMS but not in females. A single injection of β-ethynyl estradiol at PND2, prevented the changes observed in RMS male mice, suggesting that estrogens may play a protective role early in life against the exposure to stressful conditions. Our findings strengthen the idea of a sex-dependent influence of RMS on long-lasting modifications in synaptic transmission, effects that may be relevant for cognitive performance.

Comparative study of the reproductive toxicity and modulation of enzyme activities by crude oil-contaminated soil before and after bioremediation

Contamination of soil with crude oil is a serious ecological problem with potential adverse public health effects. This study assessed the germ cell toxicity of simulated leachates from crude oil-contaminated soil before and after bioremediation using the murine sperm abnormality assay, sperm count, and testes histopathology. The levels of Total Testosterone (TT), Follicle Stimulating Hormone (FSH), and Luteinizing Hormone (LH); and activities of catalase (CAT), alkaline phosphatase (ALP), superoxide dismutase (SOD), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were determined. The physicochemical, Total Petroleum Hydrocarbon (TPH), and heavy metal analyses of the leachates were also carried out. Male mice were exposed to 50, 25, 10, 5, and 1% (v/v; leachate:distilled water) of the leachate samples for five consecutive days, and were sacrificed after 35 days. The result showed a statistically significant (p < 0.05), concentration-dependent increase in abnormal sperm cells in exposed mice, with aberrations such as folded sperm, amorphous head, wrong tail attachment, distal droplet, no hook, and looped tail. Data further showed a concentration-dependent significant reduction in mean sperm count in the exposed mice. Alterations of seminiferous tubules with different lesions and activities of ALT, AST, ALP, FSH, LH, and TT were also recorded. The high level of selected heavy metals (As, Cr, Cd, Cu, and Pb) and TPH was believed to contribute to the observed reproductive toxicity and modulated enzyme activities in the treated mice. It is therefore concluded that the microbial remediation of the crude oil contaminated soil produced a reduction in the levels of heavy metals and TPH in the soil, reduced reproductive toxicity, and modulation of enzyme activities. However, the induced reproductive toxicity by the bioremediated soil is still significant, hence, further work could be done to employ a consortium of bacteria and extend the period of the bioremediation process to ensure complete removal of the contaminants.

Environmental and occupational exposures associated with male infertility

The upsurge in male infertility over the last two decades, possibly due to environmental exposure, has raised significant interest, particularly boosted by reports from fertility clinics, which showed that chronic diseases and hereditary or other medical conditions might only partially explain current incidence of male infertility. Both environmental and occupational settings may have a significant role in exposure to complex mixtures of endocrine disruptors (ED), which play a major role in fertility disorders. The aim of this review is to give an insight into the current knowledge on exposure settings which may be associated with male infertility. Our study relied on a systematic search of PubMed, Scopus, and Web of Science for articles published between January 2000 and September 2020. It showed that some well documented factors associated with male infertility include smoking, and physiological disturbances or chronic diseases such as obesity and diabetes, which in turn, may also reflect lifestyle choices and environmental exposures, especially to EDs such as phthalates, bisphenols, pesticides, and flame retardants. However, the number of studies on the aetiology of male infertility is still too low in comparison with the size of affected population. Occupational health follow-ups and medical surveillance do not collect any data on male infertility, even though ED chemicals are part of many technological processes.

Circulating sex hormone levels in relation to male sperm quality

BACKGROUND

Although sex hormones play critical roles in spermatogenesis and sperm maturation, it remains inconclusive whether circulating sex hormones can serve as non-invasive biomarkers to improve the assessment of sperm quality.

METHODS

We systematically evaluated the association of various sex hormones in serum with sperm quality among 338 men in subfertile couples. Concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), total testosterone (TT), total estradiol (E2), and sex hormone-binding globulin (SHBG) were detected by chemiluminescent immunoassay. Free testosterone and estradiol were calculated using a validated algorithm. A generalized liner regression model controlling for lifestyle factors was used to evaluate the associations with sperm count, concentration, motility, and morphology.

RESULTS

After adjusting for age, body mass index, current smoking and alcohol drinking, LH, FSH, and TT levels were all inversely associated with sperm motility (all P for trend < 0.05); however, in mutual adjustment analysis, only LH remained an inverse association with sperm motility after adjusting for FSH and TT levels (P for trend = 0.04). Higher concentrations of LH were also associated with lower sperm progressive motility (P for trend = 0.04). Moreover, LH and FSH levels were both inversely associated with normal sperm morphology (P for trend = 0.04 and 0.02, respectively).

CONCLUSIONS

Increased levels of LH are associated with poor sperm motility and morphology, suggesting that LH may play a central role in sperm maturation. Future studies are warranted to assess potential clinical utility of LH for risk stratification and tailed prevention of male infertility.

Protective effects of Lycium barbarum polysaccharide on male sexual dysfunction and fertility impairments by activating hypothalamic pituitary gonadal axis in streptozotocin-induced type-1 diabetic male mice

Diabetes-associated male sexual dysfunction and fertility impairments are both common clinical complications with limited therapeutic options; hence it seriously affects the quality of life of the patients, in particular, the patients of reproductive age. Lycium barbarum polysaccharide (LBP) has long being believed to maintain and to promote reproductive functions in the traditional medical practice in China. The current study was to investigate if LBP may contribute to recovery of male sexual dysfunction and fertility impairments in diabetic individuals. The effects of LBP on sexual behaviors and histological changes of testis were studied in the type-1 diabetes male mice induced by intra-peritoneal (i.p.) injection of streptozotocin (STZ). After oral administration of LBP (10, 20 or 40 mg/kg), sildenafil citrate (SC, 5 mg/kg) or saline for 62 consecutive days, the typical abnormal changes in the sperm parameters, in relative weight of reproductive organs and in morphology of testis were observed in diabetic mice. LBP treatment of the diabetic mice considerably reversed those changes and Johnsen's testicular score, serum testosterone (T), follicular stimulating hormone (FSH) and luteinizing hormone (LH) level were also increased to different degrees. Moreover, our data have also shown that a marked improvement in sexual behavior and fertility level after administration of LBP (40 mg/kg) compared to the diabetic group. These results suggested that LBP can exert functional recovery of male sexual dysfunction and fertility damages induced by diabetes in male mice, which is likely to be mediated through regulating the hypothalamus- pituitary-gonadal axis endocrine activity.

Stress alters the expression of cancer-related genes in the prostate

Background

Prostate cancer is a major contributor to mortality worldwide, and significant efforts are being undertaken to decipher specific cellular and molecular pathways underlying the disease. Chronic stress is known to suppress reproductive function and promote tumor progression in several cancer models, but our understanding of the mechanisms through which stress contributes to cancer development and progression is incomplete. We therefore examined the relationship between stress, modulation of the gonadotropin-releasing hormone (GnRH) system, and changes in the expression of cancer-related genes in the rat prostate.

Methods

Adult male rats were acutely or repeatedly exposed to restraint stress, and compared to unstressed controls and groups that were allowed 14 days of recovery from the stress. Prostate tissue was collected and frozen for gene expression analyses by PCR array before the rats were transcardially perfused; and brain tissues harvested and immunohistochemically stained for Fos to determine neuronal activation.

Results

Acute stress elevated Fos expression in the paraventricular nucleus of the hypothalamus (PVH), an effect that habituated with repeated stress exposure. Data from the PCR arrays showed that repeated stress significantly increases the transcript levels of several genes associated with cellular proliferation, including proto-oncogenes. Data from another array platform showed that both acute and repeated stress can induce significant changes in metastatic gene expression. The functional diversity of genes with altered expression, which includes transcription factors, growth factor receptors, apoptotic genes, and extracellular matrix components, suggests that stress is able to induce aberrant changes in pathways that are deregulated in prostate cancer.

Conclusions

Our findings further support the notion that stress can affect cancer outcomes, perhaps by interfering with neuroendocrine mechanisms involved in the control of reproduction.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3635-4) contains supplementary material, which is available to authorized users.

The effect of red wine consumption on hormonal reproductive parameters and total antioxidant status in young adult male rats

Very little is known about the effects of red wine consumption on male reproductive functions. Here we report the effect of regular drinking of different types of red wine on hormonal reproductive parameters and total antioxidant status in young adult male rats. Dry red wine (D-RW) exerted higher antioxidant activity and was characterized by higher concentration of phenolic compounds compared to semi-dry (SD-RW), sweet (S-RW) and semi-sweet (SS-RW) wines. No differences in total antioxidant status of rat plasma after six weeks of drinking of the wines were detected. Increased plasma follicle-stimulating hormone levels in S-RW versus control and D-RW (5.26 vs. 3.06 and 3.21 ng mL(-1)) groups were found. The plasma testosterone concentration was lower in D-RW compared to control, SD-RW, S-RW and SS-RW groups (0.25 vs. 1.12, 1.09, 1.54 and 1.25 ng mL(-1)). Higher plasma 17β-estradiol level in S-RW versus SD-RW and SS-RW (10.94 vs. 7.18 and 6.72 pg mL(-1)) group was stated. The prolactin level was higher in plasma of S-RW versus D-RW and SS-RW (17.35 vs. 9.74 and 8.59 ng mL(-1)) rats. The effects of red wine drinking on the hormonal regulation of the male reproductive system depend on the type and the dose of red wine. Chemical compounds naturally occurring in red wines (i.e. phenolics) may modulate the effects of ethyl alcohol, but also directly affect the male reproduction.

RiboTag analysis of actively translated mRNAs in Sertoli and Leydig cells in vivo

Male spermatogenesis is a complex biological process that is regulated by hormonal signals from the hypothalamus (GnRH), the pituitary gonadotropins (LH and FSH) and the testis (androgens, inhibin). The two key somatic cell types of the testis, Leydig and Sertoli cells, respond to gonadotropins and androgens and regulate the development and maturation of fertilization competent spermatozoa. Although progress has been made in the identification of specific transcripts that are translated in Sertoli and Leydig cells and their response to hormones, efforts to expand these studies have been restricted by technical hurdles. In order to address this problem we have applied an in vivo ribosome tagging strategy (RiboTag) that allows a detailed and physiologically relevant characterization of the "translatome" (polysome-associated mRNAs) of Leydig or Sertoli cells in vivo. Our analysis identified all previously characterized Leydig and Sertoli cell-specific markers and identified in a comprehensive manner novel markers of Leydig and Sertoli cells; the translational response of these two cell types to gonadotropins or testosterone was also investigated. Modulation of a small subset of Sertoli cell genes occurred after FSH and testosterone stimulation. However, Leydig cells responded robustly to gonadotropin deprivation and LH restoration with acute changes in polysome-associated mRNAs. These studies identified the transcription factors that are induced by LH stimulation, uncovered novel potential regulators of LH signaling and steroidogenesis, and demonstrate the effects of LH on the translational machinery in vivo in the Leydig cell.

Evaluation of FSH, LH and testosterone levels in different subgroups of infertile males

Gonadotropins (FSH, LH) and testosterone are the prime regulators of germ cell development. Abnormal spermatogenesis is often associated with altered serum gonadotropins and testosterone. FSH, LH and testosterone levels were estimated in 96 infertile men of whom 35 were azoospermic, 35 were oligozoospermic, 11 were with varicocele and 15 were with histopathological abnormalities like hypospermatogenesis, spermatid arrest and sertoli-cell only syndrome. Results showed statistically significant (p<0.05), increase in the mean FSH and LH levels in all the infertile males studied when compared with the fertile controls (n=35). However, there is no significant difference in the mean levels of testosterone between the infertile and fertile men.

Withania somnifera improves semen quality by regulating reproductive hormone levels and oxidative stress in seminal plasma of infertile males

OBJECTIVE

To investigate the impact of Withania somnifera roots on semen profile, oxidative biomarkers, and reproductive hormone levels of infertile men.

DESIGN

Prospective study.

SETTING

Departments of Biochemistry and Urology, Chhatrapati Shahuji Maharaj Medical University, Lucknow, India.

PATIENT(S)

Seventy-five normal healthy fertile men (control subjects) and 75 men undergoing infertility screening.

INTERVENTION(S)

High-performance liquid chromatography assay procedure for quantization of vitamin A and E in seminal plasma. Biochemical parameters in seminal plasma were estimated by standard spectrophotometric procedures. Estimation of T, LH, FSH, and PRL in blood serum by RIA methods.

MAIN OUTCOME MEASURES(S)

Before and after the treatment, seminal plasma biochemical parameters, antioxidant vitamins, and serum T, LH, FSH, and PRL levels were measured.

RESULT(S)

Withania somnifera inhibited lipid peroxidation and protein carbonyl content and improved sperm count and motility. Treatment of infertile men recovered the seminal plasma levels of antioxidant enzymes and vitamins A, C, and E and corrected fructose. Moreover, treatment also significantly increased serum T and LH and reduced the levels of FSH and PRL.

CONCLUSION(S)

The treatment with W. somnifera effectively reduced oxidative stress, as assessed by decreased levels of various oxidants and improved level of diverse antioxidants. Moreover, the levels of T, LH, FSH and PRL, good indicators of semen quality, were also reversed in infertile subjects after treatment with the herbal preparation.

beta-estradiol 3-benzoate affects spermatogenesis in the adult mouse

beta-estradiol 3-benzoate (E(2)B) (10, 16, 20, 40, 80 and 160 microg/kg body weight) was administered daily to experimental groups of adult mice for the following periods; 2, 3 days, 1, 2, 4, and 8 weeks. Morphological changes in the testes were observed by both light and electron microscopy. Exfoliation of the germ cells was observed in the lumen of the seminiferous tubule. The spermatogenic cycle, especially stage XII, was disordered. Spermatids older than step 6 were severely affected. Detected abnormalities in the spermatids were deformation of the nucleus and acrosome. Partial deletion in the Sertoli-spermatid ectoplasmic specialization was also observed. Germ cells younger than step 7 spermatids were not affected morphologically. These abnormalities were not detected in the mice treated with the chemical at less than 16 microg/kg body weight. It is concluded that the chemical seems to affect round spermatids metabolically, but the morphological effect can be detected only from the spermatids older than step 6. The effects of the chemical on adult mice were reversible.

Reproduction: Effect of GNRH and HCG administration on plasma LH and testosterone concentrations in normal stallions, aged stallions and stallions with lack of libido

Gonadotrophin-releasing hormone (GnRH) (a single intravenous injection with 0.042 mg busereline acetate) was administered to control stallions (n=5), aged stallions (n=5) and stallions with lack of libido (n=5). Jugular blood samples were taken at -10, 0, 10, 20, 40 and 80 minutes after treatment and measured for luteinizing hormone (LH) and testosterone concentrations. A single intravenous injection of hCG (3000 IE) was given 1 day later. Venous blood samples were taken at -60, 0, 15, 30, 60, 120, and 240 minutes after treatment and measured for the testosterone concentration. The experiment was performed in the breeding season. There was a wide variation between stallions in basal concentrations of LH and testosterone. The treatment groups all showed a significant increase in LH and testosterone concentrations after treatment with GnRH. There was a significant difference (P<0.05) between the control, the lack of libido stallions and the aged stallions in the production of LH before and after stimulation with GnRH. The aged stallions had higher basal LH concentrations. GnRH induced a rise in plasma LH in all groups, but the greatest response was observed in aged stallions. No response to GnRH was seen with respect to plasma testosterone. There was an increase in plasma testosterone following hCG; however, this increase was very small in aged stallions. After stimulation with hCG the control and lack of libido stallions had a significant increase (P<0.05) in testosterone production. In conclusion, stimulation with either GnRH or hCG can be a valuable method to test whether the function of the stallion's reproductive endocrine system is optimal.

Morphometric studies on the testes of rats treated neonatally with oestrogen and subsequently with gonadotrophins and testosterone

The experiments involved male rats, which were given a single subcutaneous dose of 1 mg stilboestrol on the first day of life. Beginning on day 28, subgroups of the rats received either gonadotrophins or testosterone for 39 days. The weight of the testes, serum luteinizing hormone and testosterone levels were determined while sections of the testes were subjected to morphological analysis and morphometric measurements, based on computerized techniques. The results demonstrated that a single dose of oestrogen caused a reduction in the cross-sectional area of the seminiferous tubules and a reduction in the thickness of the seminiferous epithelium, accompanied by inhibition of spermatogenesis. The number of and area occupied by Leydig cells, as well as the size of their cell nuclei, were also diminished, and the levels of serum testosterone decreased by 73%. All the experimental animals manifested significantly increased serum luteinizing hormone levels. Stimulation with gonadotrophins markedly increased the number of Leydig cells, their size and the size of their cell nuclei. This was associated with significantly increased levels of serum testosterone. Under these conditions, the cross-sectional area of the seminiferous tubules and the thickness of seminiferous epithelium remained less than those in the untreated controls. Following stimulation with testosterone the pattern of the seminiferous tubules resembled that noted after stimulation with gonadotrophins; the number of Leydig cells was markedly reduced but the size of both the cells themselves and of their nuclei approached normal values.