Changes in Levels of Seminal Nitric Oxide Synthase, Macrophage Migration Inhibitory Factor, Sperm DNA Integrity and Caspase-3 in Fertile Men after Scrotal Heat Stress

Effect of bioactive peptides on heat stress-induced testiculopathies in mature rats: immunohistopathological evidence

Exposure to extreme temperature conditions such as occurs in certain occupations is known to induce male infertility. In humans and most of the mammals, it has been shown that whole-body heat stress (HS) decreases fertility and produces defective embryos. Hence, the present study aimed at gaining some insights into the mechanisms producing defects after HS. In the present study, 56 mature male Wistar rats were randomly categorized into eight groups (n = 7), including group 1: Control, groups 2: Bioactive peptides (BPs; 10.00 mg kg-1), groups 3, 4, and 5: Heat-stressed (37.00, 39.00, and 43.00 ˚C for 20 min, respectively), and groups 6, 7, and 8: Heat-stressed along with BPs (10.00 mg kg-1), respectively. All treatments were administered orally once per day. The HS was induced through the immersion of rat scrotums in a water bath. After 45 days, rats were sacrificed and left testes were removed, fixed, and used for histological and immunohistochemical studies. Harvested right testes were also used for oxidative stress assessments and molecular analyses. Heat stress increased testicular tissue damage, elevated oxidative stress and reactive oxygen species production, and increased germ cells apoptosis, p53 and caspase 3 expressions, and Bax/Bcl-2 ratio. Treatment with BPs as a substance with anti-oxidant properties ameliorated the damage caused by HS. The results of this study highlight the protective role of BPs in the reproductive tract under HS. Bioactive peptides may have potential function against testicular tissue oxidative stress and apoptosis.

The sitting men: A systematic review of spare and working time exposure to sedentariness in relation to semen parameters

BACKGROUND

Over the past few decades, several studies have found that semen quality parameters have steadily declined over time. Many hypotheses have been made to explain this finding, among which a sedentary lifestyle has been investigated. To synthesize the current evidence, we performed a systematic review of published papers reporting on the relationship between sedentary habits and semen parameters.

METHODS

Embase and PubMed were systematically searched for papers published in English up to May 2023. We included all full-text observational papers that reported the relationship between sedentariness and semen parameters. Article selection adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines.

RESULTS

Sixteen observational studies were ultimately included, six in healthy men and ten in men from Fertility Clinics. They encompassed a total of 13,509 men, with 9877 being healthy men and 3632 presenting at Fertility Clinics for initial assessment. In terms of semen volume, no association emerged in the six studies involving healthy men: however, results in men referring to fertility clinics mainly showed no association, with one indicating a decline and one higher volume. Twelve studies did not report differences in sperm concentration, while one study in men from Fertility Clinics and two in healthy men observed a decline in this parameter with increasing time spent on TV watching or sedentary posture in spare time. Total sperm count was found to be similar across groups of inactivity, except for one study that showed a significant decrease when men from Fertility Clinics spent more time watching TV. No significant differences were reported in sperm motility across all studies, with only one study, among those addressing sperm morphology, indicating a lower percentage of normal forms in men watching TV more than 3 h per day. Finally, three studies conducted in men referring to Fertility Clinics analyzed the sperm DNA fragmentation index. Two of these studies found a higher DNA fragmentation index in men spending more time per day in a sitting posture.

CONCLUSIONS

This review suggests a weak association between time spent sitting during spare time and sperm concentration, but the findings are inconsistent, highlighting the need for further research.

Phytochemical Evaluation of Lepidium meyenii, Trigonella foenum-graecum, Spirulina platensis, and Tribulus arabica, and Their Potential Effect on Monosodium Glutamate Induced Male Reproductive Dysfunction in Adult Wistar Rats

Monosodium glutamate (MSG), a sodium salt derived from glutamic acid, is widely used in commercial food products to improve taste, quality, and preservation. However, its consumption may have detrimental effects on male reproductive function. Nevertheless, plant extracts, such as Lepidium meyenii (Maca), Trigonella foenum-graecum (Fenugreek), Spirulina platensis (Spirulina), and Tribulus arabica (Tribulus), may ameliorate these adverse effects. To this effect, the phytochemical properties of Lepidium meyenii, Trigonella foenum-graecum, Spirulina platensis, and Tribulus arabica were assessed, and their potential impact on MSG-induced impairment of reproductive parameters was examined. The phytochemical composition (steroids, terpenes, phenols, flavonoids) of the plants was profiled through spectrophotometry and the antioxidant activity was assessed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Thirty-six male Wistar rats were divided into six groups at random: a control group receiving distilled water, and five experimental groups (MSG, Maca, Fenugreek, Spirulina, and Tribulus) receiving 900 mg/kg/day of MSG dissolved in water for 45 days. Subsequently, the animals in the experimental groups were administered 500 mg/kg/day of the respective plant extract via oral gavage for an additional 35 days, while the MSG group continued to receive water only. Following the treatment period, the animals were sacrificed, and their reproductive tract organs were collected, weighed, and subjected to further analysis. Phytochemical analysis revealed the presence of diverse bioactive elements in the plant extracts, including phenolic and flavonoid compounds. Exposure to MSG negatively impacted total and progressive sperm motility, which was ameliorated by Lepidium meyenii treatment. Sperm morphology showed no significant differences among groups. Treatment of the phytochemical agents diminished histomorphometric alternations of the testicular length, germinal epithelium height, and number of cells in seminiferous tubules, which were caused by the initial administration of MSG. Testosterone and LH levels were reduced in the MSG group but improved in extract-treated groups. The study suggests Lepidium meyenii as a potential remedy for reproductive dysfunction. However, further investigation into its mechanisms and human safety and efficacy is warranted.

Oxidative Stress Biomarkers in Male Infertility: Established Methodologies and Future Perspectives

Male fertility can be affected by oxidative stress (OS), which occurs when an imbalance between the production of reactive oxygen species (ROS) and the body's ability to neutralize them arises. OS can damage cells and influence sperm production. High levels of lipid peroxidation have been linked to reduced sperm motility and decreased fertilization ability. This literature review discusses the most commonly used biomarkers to measure sperm damage caused by ROS, such as the high level of OS in seminal plasma as an indicator of imbalance in antioxidant activity. The investigated biomarkers include 8-hydroxy-2-deoxyguanosine acid (8-OHdG), a marker of DNA damage caused by ROS, and F2 isoprostanoids (8-isoprostanes) produced by lipid peroxidation. Furthermore, this review focuses on recent methodologies including the NGS polymorphisms and differentially expressed gene (DEG) analysis, as well as the epigenetic mechanisms linked to ROS during spermatogenesis along with new methodologies developed to evaluate OS biomarkers. Finally, this review addresses a valuable insight into the mechanisms of male infertility provided by these advances and how they have led to new treatment possibilities. Overall, the use of biomarkers to evaluate OS in male infertility has supplied innovative diagnostic and therapeutic approaches, enhancing our understanding of male infertility mechanisms.

Implications of Exposure to Air Pollution on Male Reproduction: The Role of Oxidative Stress

Air pollution, either from indoor (household) or outdoor (ambient) sources, occurs when there is presence of respirable particles in the form of chemical, physical, or biological agents that modify the natural features of the atmosphere or environment. Today, almost 2.4 billion people are exposed to hazardous levels of indoor pollution, while 99% of the global population breathes air pollutants that exceed the World Health Organization guideline limits. It is not surprising that air pollution is the world's leading environmental cause of diseases and contributes greatly to the global burden of diseases. Upon entry, air pollutants can cause an increase in reactive oxygen species (ROS) production by undergoing oxidation to generate quinones, which further act as oxidizing agents to yield more ROS. Excessive production of ROS can cause oxidative stress, induce lipid peroxidation, enhance the binding of polycyclic aromatic hydrocarbons (PAHs) to their receptors, or bind to PAH to cause DNA strand breaks. The continuous and prolonged exposure to air pollutants is associated with the development or exacerbation of pathologies such as acute or chronic respiratory and cardiovascular diseases, neurodegenerative and skin diseases, and even reduced fertility potential. Males and females contribute to infertility equally, and exposure to air pollutants can negatively affect reproduction. In this review, emphasis will be placed on the implications of exposure to air pollutants on male fertility potential, bringing to light its effects on semen parameters (basic and advanced) and male sexual health. This study will also touch on the clinical implications of air pollution on male reproduction while highlighting the role of oxidative stress.

Trend of change of sperm count and concentration over the last two decades: A systematic review and meta-regression analysis

BACKGROUND

Since the 1970s, several studies found that sperm concentration (SC) and total sperm count (TSC) constantly worsened over time, mainly in high-income countries.

OBJECTIVES

To evaluate whether the decreasing trend in sperm count is continuing in Western European countries and USA, we performed a systematic review and meta-regression analysis.

MATERIALS AND METHODS

Embase and Pubmed/Medline were searched papers published in English in the 2000-2020 period limiting the search to data collected in the USA and Western European countries.

RESULTS

We identified 62 articles and pooled information on 24,196 men (range 10-2,523), collected from 1993 to 2018. Considering all the studies, random-effects meta-regression analyses showed no significant trend for SC (slope per year -0.07 mil/mL, p-value = 0.86). Negative trends of SC were detected in Scandinavian countries (slope per year -1.11 mil/mL, 95% CI: -2.40 to +0.19; p-value = 0.09), but the findings were statistically not significant. No significant trends of SC were detected in Central Europe (slope per year +0.23, 95% CI -2.51 to +2.96; p-value = 0.87), the USA (slope per year +1.08, 95% CI -0.42 to +2.57; p-value = 0.16), and Southern Europe (slope per year +0.19, 95% CI -0.99 to +1.37; p-value = 0.75). We have analyzed separately findings from studies including sperm donors, fertile men, young unselected men (unselected men, study mean age < 25 years) and unselected men (unselected men, study mean age ≥ 25 years). No significant trends of SC were observed among sperm donors (slope per year -2.80, 95% CI -6.76 to +1.17; p-value 0.16), unselected men (slope per year -0.23, 95% CI -1.58 to +1.12; p-value 0.73), young unselected men (slope per year -0.49, 95% CI -1.76 to +0.79; p-value 0.45), fertile men (slope per year +0.29, 95% CI -1.09 to +1.67; p-value 0.68).

DISCUSSION AND CONCLUSION

The results of this analysis show no significant trends in SC, in USA, and selected Western European countries.

High-fat diet in mice led to increased severity of spermatogenesis impairment by lead exposure: perspective from gut microbiota and the efficacy of probiotics

BACKGROUND

The mechanism of multifactorial spermatogenesis impairment is unclear. This study aimed to investigate the reproductive toxicity of lead (Pb) in mice fed a high-fat diet (HFD) and to delineate the important role of gut microbiota.

RESULTS

Results showed that, compared with mice fed a normal diet (ND), Pb exposure caused more severe spermatogenesis impairment in HFD-fed mice, including decreased sperm count and motility, seminiferous tubule injury, serum and intratesticular testosterone decline, and downregulated expression level of spermatogenesis-related genes. Besides, 16S sequencing indicated that HFD-fed mice had increased severity of gut microbiota dysbiosis by Pb exposure compared to ND-fed mice. With fecal microbiota transplantation, the same trend of spermatogenesis impairment occurred in recipient mice, which confirmed the important role of gut microbiota. Moreover, probiotics supplementation restored the gut microbial ecosystem, and thus improved spermatogenic function.

CONCLUSION

Our work suggested that a population with HFD might face more reproductive health risks upon Pb exposure, and revealed an intimate linkage between microbiota dysbiosis and spermatogenesis impairment, accompanied by the potential usefulness of probiotics as prophylactic and therapeutic. © 2022 Society of Chemical Industry.

The Impact of High Ambient Temperature on Human Sperm Parameters: A Meta-Analysis

Background

Global warming, lifestyle, or working in a high temperature environment leads to have increased health risk factors. This meta-analysis was conducted to determine the impact of high ambient temperature on male reproductive function.

Methods

Scientific articles were screened in the database including MEDLINE, EMBASE, National center for biotechnology information (NCBI) or Web of Science with relating keywords. Impact data of high ambient temperature on semen parameters were extracted and analyzed by STATA software according to the Random Effects Model. The high ambient temperature exposure group and Non-exposure group were compared using the standard mean difference (SMD). Publications were evaluated for publication bias by Egger test.

Results

Nine articles were finally selected from databases examining the effect of high ambient temperature on male reproductive health of 356 men from Iran, Italy, Thailand, China, Egypt. High ambient temperature showed a significant decrease in the seminal parameters, semen volume during each ejaculation (SMD = -0.74; 95% CI -1.11, -0.36), sperm concentration (SMD = -1.07; 95% CI -1.42, -0.72), total sperm count (SMD = -1.52; 95% CI -2.96, -0.08), sperm motility (SMD = -1.93; 95% CI -2.83, -1.04), sperm progressive motility (SMD = -1.65; 95% CI -2.39, -0.91) and normal morphology (SMD = -2.41; 95% CI -3.30, -1.52).

Conclusion

High ambient temperature negatively affects sperm quality, including decreased semen volume, sperm count, sperm concentration, motility and normal morphology. This might lead to protective strategies to avoid the adverse effects of high ambient temperature on male fertility.

Beyond conventional sperm parameters: the role of sperm DNA fragmentation in male infertility

Infertility is a condition that widely affects the couples all over the world. In this regard, sperm DNA fragmentation can lead to harmful reproductive consequences, including male infertility and poor outcomes after assisted reproductive techniques. The investigation of SDF in male infertility diagnostics has constantly increased over time, becoming more common in clinical practice with the recent publication of several guidelines regarding its testing. This narrative review aims to provide a comprehensive overview of the pathogenesis and causes of sperm DNA fragmentation, as well as the assays which are more commonly performed for testing. Moreover, we discussed the most recently published evidence regarding the use of SDF testing in clinical practice, highlighting the implications of high sperm DNA fragmentation rate on human reproduction, and the therapeutic approaches for the clinical management of infertile patients. Our review confirms a significant harmful impact of sperm DNA fragmentation on reproduction, and points out several interventions which can be applied in clinics to reduce sperm DNA fragmentation and improve reproductive outcomes. Sperm DNA fragmentation has been shown to adversely impact male fertility potential. As high sperm DNA fragmentation levels have been associated with poor reproductive outcomes, its testing may significantly help clinicians in defining the best therapeutic strategy for infertile patients.

Examination of clinical data and semen analysis results of patients undergoing orchiectomy for testicular tumor

OBJECTIVE

Testicular tumor constitutes 1% of male neoplasms. Infertility can be determined in patients with testicular tumors before orchiectomy due to the deterioration of spermatogenesis. The aim of this study was to show the clinical, radiological, and pathological characteristics and spermiogram results of patients with testicular tumor and their relationship with each other.

METHODS

The data of patients who underwent orchiectomy due to testicular tumor between 2016 and 2019 were reviewed retrospectively. These data included sociodemographic data of the patients, pretreatment spermiogram characteristics, level of serum tumor markers, characteristics of the ultrasonography, type of orchiectomy, and histopathological examination.

RESULTS

This study included 53 male patients, with a mean age of 33.51±12.86 years. The mean levels of all tumor markers were above the reference levels. The mean tumor size was 34.68±23.32 mm. Multiple localizations and microlithiasis were detected in 11.3 and 13.2% of the tumors, respectively. The most common masses were hypoechoic (n=37; 69.8%) and hypervascular (n=47; 81%). Spermiogram and cryopreservation were performed in 29 (54.7%) of 53 patients preoperatively. The mean sperm concentration before orchiectomy was 24.21×106 /mL and group A sperm motility 0.79%, group B sperm motility 39.10%, group C sperm motility 9.83%, and group D sperm motility 22.69% in testicular tumors.

CONCLUSION

Spermatogenesis adversely affected before the treatment due to local and systemic effects of testicular cancer. Fertility expectations can be increased in the subsequent years by semen analysis and referral to cryopreservation.

Sperm Parameters, ASAs and Apoptosis After Processing by the Double Tube and Swim up Methods

The aim of this study was to improve the quality of semen samples by using a novel double-tube (DT) method. The DT method was developed to select sperm and compared with traditional swim-up (SU) technique for 31 semen samples. Sperm DNA integrity were tested with TUNEL and SCSA. Content of antisperm antibodies (ASA) in the semen was measured by ELISA and MAR. Levels of the caspase-3 in the sperm were assessed by western blotting. After SU and DT, 15 couples and 16 couples were underwent IVF-ET. The number of RCDs, the percentage of SDF and DFI, ASA and the level of caspase-3 were significantly decreased after DT and SU (p = .001 and p< .001). When the DT and SU compared, there were significant changes in the number of RCD, the percentage of SDF and DFI, ASA and the level of caspase-3 (p< 0.05-0.001). There was a higher cleavage rate (p = .017) and a lower abortion rate (p< .05) in DT-IVF group than in SU-IVF group. DT selection yielded spermatozoa with low RCDs, DFI, ASA, and caspase-3 which would be benefit for ART.

Effect of diclofenac on semen quality: A review

Diclofenac is an effective nonsteroidal anti-inflammatory drug and one of the most prescribed medicines worldwide. So far, there are many published articles that directly link between diclofenac and semen quality; however, hitherto, there is no collective review or comprehensive discussion that reveal such imperative link. Therefore, this work reviews and judges the association between diclofenac administration and semen quality, henceforth male infertility. As a tool to accomplish this scientific input, Scopus, Embase and PubMed databases have been searched for all original articles using the keywords "diclofenac" versus "semen" and "sperm" since August 1987 through November 2020. In summary, diclofenac appears to induce negative effects on both qualitative and quantitative measures of sperm; however, this conclusion requires confirmation by human studies. The detected negative effects of diclofenac on semen quality measures may be owed to reduced levels of gonadal hormones, decreased antioxidant defence mechanism, increased oxidative stress, altered concentrations of nitric oxide that are required to maintain normal sperm physiology and reduced synthesis of prostaglandins.

The current status and future of andrology: A consensus report from the Cairo workshop group

BACKGROUND

In attempting to formulate potential WHO guidelines for the diagnosis of male infertility, the Evidence Synthesis Group noted a paucity of high-quality data on which to base key recommendations. As a result, a number of authors suggested that key areas of research/evidence gaps should be identified, so that appropriate funding and policy actions could be undertaken to help address key questions.

OBJECTIVES

The overall objective of this Consensus workshop was to clarify current knowledge and deficits in clinical laboratory andrology, so that clear paths for future development could be navigated.

MATERIALS AND METHODS

Following a detailed literature review, each author, prior to the face-to-face meeting, prepared a summary of their topic and submitted a PowerPoint presentation. The topics covered were (a) Diagnostic testing in male fertility and infertility, (b) Male fertility/infertility in the modern world, (c) Clinical management of male infertility, and (d) The overuse of ICSI. At the meeting in Cairo on February 18, 2019, the evidence was presented and discussed and a series of consensus points agreed.

RESULTS

The paper presents a background and summary of the evidence relating to these four topics and addresses key points of significance. Following discussion of the evidence, a total of 36 consensus points were agreed.

DISCUSSION

The Discussion section presents areas where there was further debate and key areas that were highlighted during the day.

CONCLUSION

The consensus points provide clear statements of evidence gaps and/or potential future research areas/topics. Appropriate funding streams addressing these can be prioritized and consequently, in the short and medium term, answers provided. By using this strategic approach, andrology can make the rapid progress necessary to address key scientific, clinical, and societal challenges that face our discipline now and in the near future.

High quality human sperm selection for IVF: A study on sperm chromatin condensation

The study consisted of semen samples of 20 male individuals who applied to Abant Izzet Baysal University Faculty of Medicine and participated in a spermiogram. The aim of this study was to determine how to obtain the healthiest spermatozoa by employing a variety of swim-up methods over differing time periods and without the use of centrifuge. Ejaculate samples were taken from the 20 patients and each patient's homogenized semen sample was divided into 4 groups without centrifugation. Group 1 was taken as the sample of untreated semen. For the other 3 groups, 250 μl of medium was added in the semen samples. Afterwards, the samples were kept at 37 °C for different time periods, 30 min for Group 2, 60 min for Group 3 and 90 min for Group 4 in order for the spermatozoa to swim to the media in the upper layer. At the end of the periods, 10 μl of propagation preparations were prepared from the swim-up fluid. Using Aniline Blue for chromatin condensation analysis, two hundred cells were immunostained by Caspase 3 for apoptotic analysis. Subsequently, the result of the four groups were compared for each test. The spermatozoa obtained at the end of the 30 min. of swim-up was compared to the spermatozoa obtained from the swim-up of 60 min., the swim-up of 90 min. It was found that the control group had statistically significant lower rates of apoptosis and was healthier in terms of chromatin integrity. The swim-up method without centrifugation is the best suited sperm preparation, based on sperm DNA integrity and sperm chromatin condensation.

High temperature suppressed SSC self-renewal through S phase cell cycle arrest but not apoptosis

BACKGROUND

High temperature has a very adverse effect on mammalian spermatogenesis and eventually leads to sub- or infertility through either apoptosis or DNA damage. However, the direct effects of heat stress on the development of spermatogonial stem cells (SSCs) are still unknown because SSCs are rare in the testes.

METHODS

In the present study, we first used in vitro-cultured SSCs to study the effect of heat shock treatment on SSC development. Then, we used RNA-Seq analysis to identify new genes or signalling pathways implicated in the heat stress response.

RESULTS

We found that 45 min of 43 °C heat shock treatment significantly inhibited the proliferation of SSCs 2 h after treatment but did not lead to apoptosis. In total, 17,822 genes were identified by RNA-Seq after SSC heat shock treatment. Among these genes, we found that 200 of them had significantly changed expression, with 173 upregulated and 27 downregulated genes. The number of differentially expressed genes in environmental information processing pathways was 37, which was the largest number. We screened the candidate JAK-STAT signalling pathway on the basis of inhibition of cell cycle progression and found that the JAK-STAT pathway was inhibited after heat shock treatment. The flow cytometry results further confirmed that heat stress caused S phase cycle arrest of SSCs.

CONCLUSION

Our results showed that heat shock treatment at 43 °C for 45 min significantly inhibited SSC self-renewal through S phase cell cycle arrest but not apoptosis.

Protective effects of Astragalin on spermatogenesis in streptozotocin-induced diabetes in male mice by improving antioxidant activity and inhibiting inflammation

Spermatogenic dysfunction is a common complication in men with diabetes and is the most important manifestation of diabetes-related male reproduction damage. Astragalin (AG) is one of the main flavonoids from Cuscuta chinensis, which has rich pharmacological activities. This study aimed to establish whether AG may contribute to the recovery from spermatogenic dysfunction. AG (3.3, 10 and 30 mg/kg) and Clomiphene (5 mg/kg) were orally administered to streptozotocin-induced diabetic male mice for 8 weeks. After the experiments performed, reproductive organs, sperm parameters and histomorphological changes were analysed. Antioxidant and anti-inflammatory capacity were estimated in testicular tissues. The results revealed that AG significantly improved the reproductive organs, sperm parameters and testicular morphology to different degrees in diabetic mice. Nitric oxide (NO) and malondialdehyde (MDA) levels were significantly reduced, and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), markedly increased in the testicular tissue after AG was administered. Interestingly, AG also downregulated the protein expressions of tumour necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) in testes. In conclusion, AG is a potential beneficial agent to protect diabetic-induced spermatogenic dysfunction in male mice by increasing antioxidant enzymes activities and inhibiting inflammation.

Type of underwear worn and markers of testicular function among men attending a fertility center

STUDY QUESTION

Is self-reported type of underwear worn associated with markers of testicular function among men at a fertility center?

SUMMARY ANSWER

Men who reported most frequently wearing boxers had higher sperm concentration and total count, and lower FSH levels, compared to men who did not.

WHAT IS KNOWN ALREADY

Elevated scrotal temperatures are known to adversely affect testicular function. However, the epidemiologic literature on type of underwear, as a proxy of scrotal temperature, and male testicular function is inconsistent.

STUDY DESIGN, SIZE, DURATION

This is a cross-sectional study including 656 male partners of couples seeking infertility treatment at a fertility center (2000-2017).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Self-reported information on type of underwear worn was collected from a take-home questionnaire. Semen samples were analyzed following World Health Organization guidelines. Enzyme immunoassays were used to assess reproductive hormone levels and neutral comet assays for sperm DNA damage. We fit linear regression models to evaluate the association between underwear type and testicular function, adjusting for covariates and accounting for multiple semen samples.

MAIN RESULTS AND THE ROLE OF CHANCE

Men had a median (interquartile range) age of 35.5 (32.0, 39.3) years and BMI of 26.3 (24.4, 29.9) kg/m2. About half of the men (53%; n = 345) reported usually wearing boxers. Men who reported primarily wearing boxers had a 25% higher sperm concentration (95% CI = 7, 31%), 17% higher total count (95% CI = 0, 28%) and 14% lower serum FSH levels (95% CI = -27, -1%) than men who reported not primarily wearing boxers. Sperm concentration and total count were inversely related to serum FSH. Furthermore, the differences in sperm concentration and total count according to type of underwear were attenuated after adjustment for serum FSH. No associations with other measured reproductive outcomes were observed.

LIMITATIONS, REASONS FOR CAUTION

Our results may not be generalizable to men from the general population. Underwear use was self-reported in a questionnaire and there may be misclassification of the exposure. The cross-sectional design limits causal inference, and residual confounding is still possible owing to lack of information on other modifiable life styles that can also modify scrotal heat (e.g. type of trousers worn, textile fabric of the underwear). Blood sampling was not limited to the morning and, as a result, we may have missed associations with testosterone or other hormones with significant circadian variation despite statistical adjustment for time of blood draw.

WIDER IMPLICATIONS OF THE FINDINGS

Certain styles of male underwear may impair spermatogenesis and this may result in a compensatory increase in gonadotrophin secretion, as reflected by higher serum FSH levels among men who reported most frequently wearing tight underwear. Confirmation of these findings, and in particular the findings on FSH levels suggesting a compensatory mechanism, is warranted.

STUDY FUNDING/COMPETING INTEREST(S)

The project was financed by Grants (R01ES022955, R01ES009718, P30ES000002, and K99ES026648) from the National Institutes of Health. None of the authors has any conflicts of interest to declare.

Environmental Toxins and Male Fertility

PURPOSE OF REVIEW

Global industrialization has increased population exposure to environmental toxins. A global decline in sperm quality over the last few decades raises questions about the adverse impact of environmental toxins on male reproductive health.

RECENT FINDINGS

Multiple animal- and human-based studies on exposure to environmental toxins suggest a negative impact on semen quality, in terms of sperm concentration, motility, and/or morphology. These toxins may exert estrogenic and/or anti-androgenic effects, which in turn alter the hypothalamic-pituitary-gonadal axis (HPGA), induce sperm DNA damage, or cause sperm epigenetic changes. This chapter will discuss the most recent literature about the most common environmental toxins and their impact on spermatogenesis and its consequences on male fertility. Understanding the presence and underlying mechanism of these toxins will help us preserve the integrity of the male reproduction system and formulate better regulations against their indiscriminate use.

Temporal trends in sperm count: a systematic review and meta-regression analysis

BACKGROUND

Reported declines in sperm counts remain controversial today and recent trends are unknown. A definitive meta-analysis is critical given the predictive value of sperm count for fertility, morbidity and mortality.

OBJECTIVE AND RATIONALE

To provide a systematic review and meta-regression analysis of recent trends in sperm counts as measured by sperm concentration (SC) and total sperm count (TSC), and their modification by fertility and geographic group.

SEARCH METHODS

PubMed/MEDLINE and EMBASE were searched for English language studies of human SC published in 1981-2013. Following a predefined protocol 7518 abstracts were screened and 2510 full articles reporting primary data on SC were reviewed. A total of 244 estimates of SC and TSC from 185 studies of 42 935 men who provided semen samples in 1973-2011 were extracted for meta-regression analysis, as well as information on years of sample collection and covariates [fertility group ('Unselected by fertility' versus 'Fertile'), geographic group ('Western', including North America, Europe Australia and New Zealand versus 'Other', including South America, Asia and Africa), age, ejaculation abstinence time, semen collection method, method of measuring SC and semen volume, exclusion criteria and indicators of completeness of covariate data]. The slopes of SC and TSC were estimated as functions of sample collection year using both simple linear regression and weighted meta-regression models and the latter were adjusted for pre-determined covariates and modification by fertility and geographic group. Assumptions were examined using multiple sensitivity analyses and nonlinear models.

OUTCOMES

SC declined significantly between 1973 and 2011 (slope in unadjusted simple regression models -0.70 million/ml/year; 95% CI: -0.72 to -0.69; P < 0.001; slope in adjusted meta-regression models = -0.64; -1.06 to -0.22; P = 0.003). The slopes in the meta-regression model were modified by fertility (P for interaction = 0.064) and geographic group (P for interaction = 0.027). There was a significant decline in SC between 1973 and 2011 among Unselected Western (-1.38; -2.02 to -0.74; P < 0.001) and among Fertile Western (-0.68; -1.31 to -0.05; P = 0.033), while no significant trends were seen among Unselected Other and Fertile Other. Among Unselected Western studies, the mean SC declined, on average, 1.4% per year with an overall decline of 52.4% between 1973 and 2011. Trends for TSC and SC were similar, with a steep decline among Unselected Western (-5.33 million/year, -7.56 to -3.11; P < 0.001), corresponding to an average decline in mean TSC of 1.6% per year and overall decline of 59.3%. Results changed minimally in multiple sensitivity analyses, and there was no statistical support for the use of a nonlinear model. In a model restricted to data post-1995, the slope both for SC and TSC among Unselected Western was similar to that for the entire period (-2.06 million/ml, -3.38 to -0.74; P = 0.004 and -8.12 million, -13.73 to -2.51, P = 0.006, respectively).

WIDER IMPLICATIONS

This comprehensive meta-regression analysis reports a significant decline in sperm counts (as measured by SC and TSC) between 1973 and 2011, driven by a 50-60% decline among men unselected by fertility from North America, Europe, Australia and New Zealand. Because of the significant public health implications of these results, research on the causes of this continuing decline is urgently needed.

Impact of a mild scrotal heating on sperm chromosomal abnormality, acrosin activity and seminal alpha-glucosidase in human fertile males

The aim of this study was to observe sperm aneuploidy, DNA integrity, seminal alpha-glucosidase (NAG) and acrosin activity (AA) under testicular heat stress (SH). Spermatozoa were obtained from 30 healthy adult volunteers subjected to scrotal warming at 43°C for 30-40 min on two successive days per week for 3 months between February 2012 and September 2016. Aniline blue (AB), acridine orange (AO) staining, TUNEL assay and FISH analysis to evaluate sperm function, sperm DNA integrity and chromosomal abnormalities were carried on before, during and after SH. Sperm AA and NAG was measured by microplate reader. The mean parameters of sperm parameters, AA and NAG were significantly decreased. In contrast, the mean percentage of sperm DNA fragmentation and the proportion of aneuploidy of chromosomes 13, 18, 21, X and Y were significantly increased for spermatozoa collected during SH versus before SH (p < .01-.001). After stopping scrotal heating for 3 months, most parameters were completely restored to pre-SH levels. Sperm parameters, sperm DNA integrity, chromosomes, AA and NAG are affected by scrotal exposure to constant SH temperatures several degrees over normal physiological temperature, and after treatment, these parameters were reversibly restored to the level before SH in adult men.

Effect of lansoprazole on human sperm motility, sperm viability, seminal nitric oxide production, and seminal calcium chelation

Lansoprazole is a proton-pump inhibitor that is commonly used to treat many gastric illnesses. However, little is known about its effect on sperm function. Here, we investigated the in vitro effect of LP on human sperm motility, viability, nitric oxide (NO) production, and the ability of LP to chelate seminal calcium. Seventy-two semen samples from normozoospermic men were tested in this study. The effects of LP at 0.375, 0.75, 1.5, and 3 μg/mL on sperm motility and viability as well as at 3 μg/mL on NO production and calcium chelation in semen were assessed. Lansoprazole at 3 μg/mL significantly decreased total and progressive sperm motility (P = 0.0021, P = 0.0256, respectively), but not sperm viability (P = 0.8763). In addition, semen samples supplemented with 3 μg/mL LP had insignificant changes (P = 0.9085) in nitrite concentrations. Moreover, LP exhibited a significant (P < 0.0001) calcium chelation effect in semen. In conclusion, LP reduced sperm motility, but not viability. The reduction in sperm motility may be due to the calcium chelating effect of LP and/or decreased Na⁺/K⁺-ATPase activity, but not an alteration in NO production. Besides, none of the tested parameters was found to be correlated with male age.

Selected sperm traits are simultaneously altered after scrotal heat stress and play specific roles in in vitro fertilization and embryonic development

Improvements in the estimation of male fertility indicators require advances in laboratory tests for sperm assessment. The aims of the present work were (1) to apply a multivariate analysis to examine sperm set of alterations and interactions and (2) to evaluate the importance of sperm parameters on the outcome of standard IVF and embryonic development. Bulls (n = 3) were subjected to scrotal insulation, and ejaculates were collected before (preinsulation = Day 0) and through 56 days (Days 7, 14, 21, 28, 35, 42, 49, and 56) of the experimental period. Sperm head morphometry and chromatin variables were assessed by a computational image analysis, and IVF was performed. Scrotal heat stress induced alterations in all evaluated sperm head features, as well as cleavage and blastocyst rates. A principal component analysis revealed three main components (factors) that represented almost 89% of the cumulative variance. In addition, an association of factor scores with cleavage (factor 1) and blastocyst (factor 3) rates was observed. In conclusion, several sperm traits were simultaneously altered as a result of a thermal insult. These sperm traits likely play specific roles in IVF and embryonic development.