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

Beneficial effect of residential greenness on sperm quality and the role of air pollution: A multicenter population-based study

BACKGROUND

Poor sperm quality is a major cause of male infertility. However, evidence remains scarce on how greenness affects male sperm quality.

OBJECTIVES

To assess the associations of residential greenness with male sperm quality and the modification effect of air pollution exposure on the relationship.

METHODS

A total of 78,742 samples from 33,184 sperm donors from 6 regions across China during 2014-2020 were included and analyzed. Individual residential greenness exposures of study subjects were estimated using the Normalized Difference Vegetation Index (NDVI) during the entire (0-90 lag days) and two key stages (0-37, and 34-77 lag days) of sperm development. Contemporaneous personal exposure levels to air pollutants were estimated using a spatio-temporal deep learning method. Linear mixed models were employed to assess the impact of greenspace in relation to sperm quality. The modification effect of air pollution on the greenspace-sperm quality relationship was also estimated.

RESULTS

Per IQR increment in NDVI exposure throughout spermatogenesis were statistically associated with increasing sperm count by 0.0122 (95 % CI: 0.0007, 0.0237), progressive motility by 0.0162 (95 % CI: 0.0045, 0.0280), and total motility by 0.0147 (95 % CI: 0.0014, 0.0281), respectively. Similar results were observed when the model added air pollutants (PM1, PM2.5 or O3) for adjustment. Additionally, specific air pollutants, including PM1, PM2.5, and O3, were found to modify this association. Notably, the protective effects of greenness exposure were more pronounced at higher concentrations of PM1 and PM2.5 and lower concentrations of O3 (all Pinteraction < 0.05). Statistically significant positive effects of NDVI were observed on sperm motility in early spermatogenesis and sperm count in late spermatogenesis.

CONCLUSIONS

Exposure to residential greenness may have beneficial effects on sperm quality and air pollution modifies their relationship. These findings highlight the importance of adopting adaptable urban greenspace planning and policies to safeguard male fertility against environmental factors.

Association between body mass index and semen quality: a systematic review and meta-analysis

The continuous decline of human semen quality during the past decades has drawn much concern globally. Previous studies have suggested a link between abnormal BMI and semen quality decline, but the results remain inconsistent. This systematic review and meta-analysis aimed to evaluate the association between body mass index (BMI) and semen quality. We searched PubMed, Embase, and Web of Science for eligible studies from inception to April 17, 2022. We considered men with BMI < 25.0 kg/m2 as the reference and calculated the pooled weighted mean difference of men with overweight (BMI 25.0-29.9 kg/m2), obesity (BMI ≥ 30.0 kg/m2), class I obesity (BMI 30.0-34.9 kg/m2), and class II/III obesity (BMI ≥ 35.0 kg/m2). A total of 5070 articles were identified, of which 50 studies were included (71,337 subjects). Compared with men with BMI < 25.0 kg/m2, men with obesity had an average reduction of 0.24 ml in semen volume, 19.56 × 106 in total sperm number, 2.21% in total motility, 5.95% in progressive motility, and 1.08% in normal forms, respectively, while men with overweight had an average reduction of 0.08 ml in semen volume and 2.91% in progressive motility, respectively. The reduction of semen quality was more pronounced among men with obesity than that among men with overweight. Moreover, significant reductions in semen quality were identified in men with different classes of obesity, which were more pronounced in men with class II/III obesity than that in men with class I obesity. Across men from the general population, infertile or subfertile men, and suspiciously subfertile men, we identified significant semen quality reductions in men with obesity/overweight. In conclusion, obesity and overweight were significantly associated with semen quality reductions, suggesting that maintaining normal weight may help prevent semen quality decline.

Diabetes and male fertility disorders

Couple infertility is a common condition, defined as being unable to conceive after 12 months of regular unprotected sexual intercourse. Male Factor Infertility (MFI) is responsible, alone or in combination with female factors, for about half of the overall cases of couple infertility. MFI is gradually increasing in prevalence, with a notable decline in semen parameters over the last decades. The aetiologies behind the finding of decreasing sperm counts are difficult to pinpoint but might be due in part to increasing rates of overweight and obesity in men of childbearing age. Diabetes mellitus (DM) is a common and chronic metabolic disease, whose prevalence is also gradually increasing, rising up to 10% of the population. The International Diabetes Federation estimates that there are currently more than 500 million people living with DM worldwide, the vast majority of whom suffering from type 2 DM (T2DM). There is growing awareness of the relationship between unhealthy lifestyle, in particular unhealthy diet, and MFI. Starting from all these premises, the aim of this narrative review is to describe the current evidence on the link between DM and MFI, both in terms of DM as a cause of/a risk factor for MFI and of MFI as a possible predictive marker for T2DM. Finally, we will discuss the risk of DM as a consequence of the therapy of MFI or assisted reproductive techniques.

Decline in reproductive health and its transgenerational lag effect

In the last two decades, there has been a fast-growing prevalence of infertility reported in China. Moreover, Chinese reproductive health has shown a clear decline. Thus, it is imperative to determine the precipitating causes and the root causes of this decline. Environmental and climate risks (ECRs) may cause the decline in reproductive health. Experimental findings have shown that the impact of ECRs on reproductive health can be passed down from both males and females to their offspring, demonstrating an intergenerational and transgenerational lag effect. We perceive that the declined reproductive health may lead to negative demographic consequences in China; therefore, we suggest the following five regulations be implemented: (i) prevent Chinese of childbearing age from exposure to ECRs; (ii) further develop and promote assisted reproductive technology and set up sperm and ovum banks on a national scale; (iii) quantitatively establish the causality between fathers and mothers who suffer from ECRs and the impaired reproductive health in their progeny; (iv) teach ECRs-health knowledge in psychotherapeutic training and continuing education; and (v) propagate and further promote common prosperity.

High-fat diet led to testicular inflammation and ferroptosis via dysbiosis of gut microbes

The disorder of gut microbiota has negative impact on male reproductive, and testicular damage is associated with obesity. However, the detailed mechanism of gut microbiota on the obesity-induced testis injury are still unknown. Therefore, we constructed a mouse model to investigate the effects of obesity on testis injury. In this study, we found that HFD-induced obesity could disorder gut microbiota homeostasis, which increased the abundance of Brevundimonas, Desulfovibrionaceae_unclassified and Ralstonia, ultimately leading to the overproduction of lipopolysaccharides (LPS). Meanwhile, HFD-feeding promoted intestinal permeability via inhibiting expression of tight junction proteins (ZO-1, Occludin and Claudin) and reducing excretion of mucus, leading to translocation of LPS. The over-accumulation of LPS in the bloodstream triggered an inflammatory response by activating TLR4/NF-κB pathway in testis. On the other hand, the gut microbiota produced-LPS also could induce ferroptosis in testis, as reflected by enhancing iron content and lipid peroxidation (MDA), as well as decreasing ferroptosis-related proteins, including GPX4, FTH1 and SLC1A11. Moreover, inhibition of LPS ligand (TLR4) with Resatorvid (TAK-242) alleviated obesity-induced testis injury through suppression of inflammation and ferroptosis. In conclusion, this study provides novel insights into the underlying mechanisms of obesity-related testis injury induced by gut microbiota disorder via the gut-testis axis, thus offering potential targets to counteract obesity-induced male reproductive disorder.

Dipeptide metabolite, glutamyl-glutamate mediates microbe-host interaction to boost spermatogenesis

The decrease in sperm count and infertility is a global issue that remains unresolved. By screening environmental bacterial isolates, we have found that a novel lactic acid bacterium, Lactiplantibacillus plantarum SNI3, increased testis size, testosterone levels, sperm count, sexual activity and fertility in mice that have consumed the bacteria for four weeks. The abundance of L. plantarum in the colon microbiome was positively associated with sperm count. Fecal microbiota transplantation (FMT) from L. plantarum SNI3-dosed mice improved testicular functions in microbiome-attenuated recipient animals. To identify mediators that confer pro-reproductive effects on the host, untargeted in situ mass spectrometry metabolomics was performed on testis samples of L. plantarum SNI3-treated and control mice. Enrichment pathway analysis revealed several perturbed metabolic pathways in the testis of treated mice. Within the testis, a dipeptide, glutamyl-glutamate (GluGlu) was the most upregulated metabolite following L. plantarum SNI3 administration. To validate the pro-reproductive feature of GluGlu, systemic and local injections of the dipeptide have been performed. γ-GluGlu increased sperm count but had no effect on testosterone. These findings highlight the role of γ-GluGlu in mediating spermatogenetic effects of L. plantarum on the male mouse host and -following relevant human clinical trials- may provide future tools for treating certain forms of male infertility.

Male Fertility as a Proxy for Health

Male fertility is affected by a wide range of medical conditions that directly and indirectly affect spermatogenesis. As such, it can be useful as both an indicator of current health and a predictive factor for future health outcomes. Herein, we discuss the current literature regarding the association between male fertility and systemic health conditions and exposures. We review the connection between male fertility and genetics, medications, diet, and environmental pollutants, as well as its effects on future oncologic, cardiovascular, and autoimmune conditions. Understanding this interplay will allow more health care providers to engage in health counseling that will not only improve men's reproductive outcomes but also their overall health.

Associations between exposure to pesticides mixture and semen quality among the non-occupationally exposed males: Four statistical models

Most epidemiological studies on the associations between pesticides exposure and semen quality have been based on a single pesticide, with inconsistent major results. In contrast, there was limited human evidence on the potential effect of pesticides mixture on semen quality. Our study aimed to investigate the relationship of pesticide profiles with semen quality parameters among 299 non-occupationally exposed males aged 25-50 without any clinical abnormalities. Serum concentrations of 21 pesticides were quantified by gas chromatography-tandem mass spectrometry (GC-MS/MS). Semen quality parameters were abstracted from medical records. Generalized linear regression models (GLMs) and three mixture approaches, including weighted quantile sum regression (WQS), elastic net regression (ENR) and Bayesian kernel machine regression (BKMR), were applied to explore the single and mixed effects of pesticide exposure on semen quality. In GLMs, as the serum levels of Bendiocarb, β-BHC, Clomazone, Dicrotophos, Dimethenamid, Paclobutrazole, Pentachloroaniline and Pyrimethanil increased, the straight-line velocity (VSL), linearity (LIN) and straightness (STR) decreased. This negative association also occurred between the concentration of β-BHC, Pentachloroaniline, Pyrimethanil and progressive motility, total motility. In the WQS models, pesticides mixture was negatively associated with total motility and several sperm motility parameters (β: -3.07∼-1.02 per decile, FDR-P<0.05). After screening the important pesticides derived from the mixture by ENR model, the BKMR models showed that the decreased qualities for VSL, LIN, and STR were also observed when pesticide mixtures were at ≥ 70th percentiles. Clomazone, Dimethenamid, and Pyrimethanil (Posterior inclusion probability, PIP: 0.2850-0.8900) were identified as relatively important contributors. The study provides evidence that exposure to single or mixed pesticide was associated with impaired semen quality.

Impact of heat waves on semen quality: A retrospective study in Argentina between 2005 and 2023

Heat waves, defined as periods with daily temperatures surpassing the historical average for a specific region, have become more frequent worldwide in recent years. Previous studies have reported a negative association between temperature and semen quality, but the focus has mainly been on Asian and European populations. The study included 54,926 men (18-60 years) undergoing routine semen analysis between 2005 and 2023 at CEUSA-LAEH andrology unit, in Buenos Aires, Argentina. Hourly temperature readings were provided by the Servicio Meteorológico Nacional. R programming (R Studio v2022.07.2) was used to define heat waves, calculate key characteristics, visualize results, and perform statistical tests at the IBYME laboratory. During the period studied, a total of 124 days had heat waves (defined after at least 3 consecutive days with 32.3 °C and 22 °C). Men exposed to heat waves during spermatogenesis exhibited lower sperm number (concentration and count; P < 0.0001) and decreased normal morphology (percentage of normal sperm and normal motile count; P < 0.05) compared to those not exposed. These differences were most pronounced between semen samples from years with several heat waves (2013, 2023) and none (2005, 2007, 2016), displaying 4-5 times higher fold changes (P < 0.05). Further analysis employing multiple regression revealed a significantly negative association between semen quality and heat wave length, suggesting that a prolonged exposure may be more detrimental than an acute exposure. Subsequent analysis focusing on prolonged exposure (≥6-days heat wave) during spermatogenesis revealed a negative (P < 0.05) association between early exposure (spermatocytogenesis: 64-90 days prior semen collection) and semen quality. This study underscores the negative association between early exposure to heat waves during sperm development and semen quality, raising concerns about its possible association with the worldwide declining male fertility. A comprehensive collaborative approach is crucial, involving global governmental policies, sustainable practices, and coordinated efforts across scientific, healthcare, and policy domains.

Male infertility and perfluoroalkyl and poly-fluoroalkyl substances: evidence for alterations in phosphorylation of proteins and fertility-related functional attributes in bull spermatozoa†

BACKGROUND

Perfluoroalkyl and poly-fluoroalkyl substances (PFAS) are pervasive environmental pollutants and potential threats to reproductive health. Epidemiological studies have established an association between PFAS and male infertility, but the underlying mechanisms are unclear.

OBJECTIVES

Investigate the effect of perfluorooctane sulfonic acid (PFOS), the most prevalent and representative PFAS, on bull sperm protein phosphorylation and function.

METHODS

We exposed bull sperm to PFOS at 10 (average population exposure) and 100 μM (high-exposure scenario), and analyzed global proteomic and phosphoproteomic analysis by TMT labeling and Nano LC-MS/MS. We also measured sperm fertility functions by flow cytometry.

RESULTS

PFOS at 10-μM altered sperm proteins linked to spermatogenesis and chromatin condensation, while at 100 μM, PFOS affected proteins associated with motility and fertility. We detected 299 phosphopeptides from 116 proteins, with 45 exhibiting differential expression between control and PFOS groups. PFOS dysregulated phosphorylation of key proteins (ACRBP, PRKAR2A, RAB2B, SPAG8, TUBB4B, ZPBP, and C2CD6) involved in sperm capacitation, acrosome reaction, sperm-egg interaction, and fertilization. PFOS also affected phosphorylation of other proteins (AQP7, HSBP9, IL4I1, PRKAR1A, and CCT8L2) related to sperm stress resistance and cryotolerance. Notably, four proteins (PRM1, ACRBP, TSSK1B, and CFAP45) exhibited differential regulation at both proteomic and phosphoproteomic levels. Flow cytometric analysis confirmed that PFOS increased protein phosphorylation in sperm and also decreased sperm motility, viability, calcium, and mitochondrial membrane potential and increased mitochondrial ROS in a dose-dependent manner.

CONCLUSIONS

This study demonstrates that PFOS exposure negatively affects phosphorylation of proteins vital for bull sperm function and fertilization.

Differentiation between nonobstructive azoospermia and obstructive azoospermia: then and now

Male infertility has seen an increase in prevalence with cases of azoospermia estimated to affect 10%-15% of infertile men. Confirmation of azoospermia subsequently necessitates an early causal differentiation between obstructive azoospermia (OA) and nonobstructive azoospermia (NOA). Although less common when compared to NOA, OA can represent upward 20%-40% of cases of azoospermia. While there are a multitude of etiologies responsible for causing NOA and OA, correctly distinguishing between the two types of azoospermia has profound implications in managing the infertile male. This review represents an amalgamation of the current guidelines and literature which will supply the reproductive physician with a diagnostic armamentarium to properly distinguish between NOA and OA, therefore providing the best possible care to the infertile couple.

Association between spectrum of mycotoxins and semen quality: A cross-sectional study in Beijing, China

Exposure to mycotoxins is unavoidable in daily life through ingestion, dermal, and inhalation routes. Toxicological studies found that exposure to mycotoxins might affect male reproductive function. However, there is still a lack of population evidence. We aimed to assess the association of individual and joint exposure to spectrum of mycotoxins with semen quality. The present study included 192 participants in Beijing, China. We measured conventional semen parameters and assessed semen quality. Sixty-seven traditional or emerging mycotoxins were determined to describe the spectrum of mycotoxins. The participants were widely exposed to multiple mycotoxins, and nearly half were simultaneously exposed to more than six mycotoxins. After adjusting potential confounders, logistic regression indicated that the number and concentration of plasma mycotoxin were correlated to the risk of low semen quality. Plasma beauvericin and citrinin concentrations were associated with lower semen quality. The least absolute shrinkage and selection operator regression showed similar results to logistic regression. Quantile-based g-computation and Bayesian kernel machine regression models found that the mixture of mycotoxins was harmful to semen quality, especially in sperm motility. In conclusion, both individual and mixture of mycotoxin exposure were correlated with lower semen quality. More regulations and measures should be taken to reduce mycotoxin contamination.

Vitamin B12 Is Associated with Higher Serum Testosterone Concentrations and Improved Androgenic Profiles Among Men with Infertility

BACKGROUND

Infertility impacts 16% of North American couples, with male factor infertility contributing to ∼30% of cases. Reproductive hormones, especially testosterone, are essential for spermatogenesis. An age-independent population-level decline in testosterone concentrations over the past few decades has been proposed to be a consequence of diet and lifestyle changes. Vitamin B12 is present in the testes and has been suggested as an adjuvant nutritional therapy for male infertility due to its potential to improve sperm parameters. However, evidence examining the relationship between vitamin B12 and reproductive hormones is limited.

OBJECTIVES

The objective was to cross-sectionally examine the relationship between serum vitamin B12 and male reproductive hormones (luteinizing hormone, follicular stimulating hormone, total testosterone, estradiol, and prolactin).

METHODS

Men with infertility (n = 303) were recruited from Mount Sinai Hospital in Toronto, Canada. Serum was analyzed for vitamin B12 and reproductive hormones. Statistical analyses included nonparametric Spearman's rank correlation coefficient, linear regression, logistic regression, and effect modification by age and BMI linear regressions.

RESULTS

An independent monotonic relationship between serum vitamin B12 and total testosterone (ρ = 0.19, P = 0.001) was observed. Serum vitamin B12 was linearly associated with total testosterone (unadjusted β = 0.0007, P = 0.008 and adjusted β = 0.0005, P = 0.03). Compared to individuals in the lowest tertile of serum vitamin B12, those in the middle tertile (adjusted odds ratio [OR] = 0.48; 95% confidence interval [CI]: 0.25, 0.93, P = 0.03) and the highest tertile (unadjusted OR = 0.41; 95% CI: 0.22, 0.77, P = 0.005 and adjusted OR = 0.44; 95% CI: 0.22, 0.87, P = 0.02) had reduced odds of testosterone deficiency.

CONCLUSIONS

These findings suggest that among men with infertility, low serum vitamin B12 is associated with a higher risk of testosterone deficiency and impaired androgenic hormonal profiles that impact spermatogenesis and consequently, fertility.

An in vitro testicular organoid model for the study of testis morphogenesis, somatic cell maturation, endocrine function, and toxicological assessment of endocrine disruptors

Male reproductive capacity has fallen considerably in recent decades; in addition, the incidence of testicular cancer has increased in many developed countries. The cause of this phenomenon is unknown, but environmental toxicants are considered a major contributing factor. To study potential reproductive toxicants, robust in vitro testis models are needed. We have recently established a porcine testis organoid system with a high resemblance to the architectures of innate testis tissue. Here, we further investigated the testis morphogenesis, cell maturation, and endocrine function of the testis organoids. We also challenged this system with abiraterone, a steroidogenic inhibitor, to validate its suitability as an in vitro platform for endocrine toxicology tests. Our results showed that the testis cells in the organoids reorganize into testis cordal structures, and the cordal relative areas increase in the organoids over time of culture. Moreover, the diameters and cell numbers per cross-section of the cordal structures increased over time. Interestingly, Sertoli cells in the organoids gradually underwent maturational changes by showing increased expression of androgen receptors, decreased expression of the anti-müllerian hormone, and formation of the blood-testis barrier. Next, we confirmed that the organoids respond to hormonal stimulation and release multiple sex hormones, including testosterone, estradiol, and progesterone. Finally, we showed that the production of testosterone and estradiol in this system can be inhibited in response to the steroidogenic inhibitor. Taken together, our organoid system provides a promising in vitro platform for male reproductive toxicology studies on testis morphogenesis, somatic cell maturation, and endocrine production.

The emergence of natural products as potential therapeutics for male infertility

Infertility is a major reproductive health problem. Approximately 50% of all documented cases of infertility are attributable to male factors, such as poor testicular function and semen quality. The recent significant global decline in sperm counts has serious implications for male fertility, but the armamentarium for improving testicular function and semen quality is limited. Natural products have a wide range of activities and are a major source of drugs for disease prevention and treatment. To provide ideas and a theoretical basis for the research and development of therapeutic drugs for male infertility, this review summarizes natural products (mostly monomers) that have been shown to improve testicular function and semen quality and their possible mechanisms of action. These natural products primarily improve testicular function and semen quality via antioxidant, antiapoptotic, and anti-inflammatory effects, in addition to increasing serum testosterone and reducing DNA damage in spermatozoa and testicular cells. Prospects for the application of natural products in the treatment of male infertility are discussed.

Episodic ozone exposure in Long-Evans rats has limited effects on cauda sperm motility and non-coding RNA populations

Epidemiological evidence suggests the potential for air pollutants to induce male reproductive toxicity. In experimental studies, exposure to ozone during sensitive windows in the sperm lifecycle has been associated with impaired sperm motility. Subsequently, we sought to investigate the effects of episodic exposure to ozone during sperm maturation in the rat. Long-Evans rats were exposed to either filtered air or ozone (0.4 or 0.8 ppm) for five non-consecutive days over two weeks. Ozone exposure did not impact male reproductive organ weights or sperm motility ∼24 hours following the final exposure. Furthermore, circulating sex hormones remained unchanged despite increased T3 and T4 in the 0.8 ppm group. While there was indication of altered adrenergic signaling attributable to ozone exposure in the testis, there were minimal impacts on small non-coding RNAs detected in cauda sperm. Only two piwi-interacting RNAs (piRNAs) were altered in the mature sperm of ozone-exposed rats (piR-rno-346434 and piR-rno-227431). Data across all rats were next analyzed to identify any non-coding RNAs that may be correlated with reduced sperm motility. A total of 7 microRNAs (miRNAs), 8 RNA fragments, and 1682 piRNAs correlated well with sperm motility. Utilizing our exposure paradigm herein, we were unable to substantiate the relationship between ozone exposure during maturation with sperm motility. However, these approaches served to identify a suite of non-coding RNAs that were associated with sperm motility in rats. With additional investigation, these RNAs may prove to have functional roles in the acquisition of motility or be unique biomarkers for male reproductive toxicity.

Endocrine disruption and male reproductive disorders: unanswered questions

Maternal exposure to endocrine-disrupting chemicals (EDCs) in human pregnancy is widely considered as an important cause of adverse changes in male reproductive health due to impaired foetal androgen production/action. However, the epidemiological evidence supporting this view is equivocal, except for certain phthalates, notably diethyl hexyl phthalate (DEHP). Maternal phthalate exposure levels associated with adverse reproductive changes in epidemiological studies are several thousand-fold lower than those needed to suppress foetal androgen production in rats, and direct studies using human foetal testis tissue show no effect of high phthalate exposure on androgen production. This conundrum is unexplained and raises fundamental questions. Human DEHP exposure is predominantly via food with highest exposure associated with consumption of a Western style (unhealthy) diet. This diet is also associated with increased exposure to the most common EDCs, whether persistent (chlorinated or fluorinated chemicals) or non-persistent (phthalates, bisphenols) compounds, which are found at highest levels in fatty and processed foods. Consequently, epidemiological studies associating EDC exposure and male reproductive health disorders are confounded by potential dietary effects, and vice versa. A Western diet/lifestyle in young adulthood is also associated with low sperm counts. Disentangling EDC and dietary effects in epidemiological studies is challenging. In pregnancy, a Western diet, EDC exposure, and maternal living in proximity to industrial sites are all associated with impaired foetal growth/development due to placental dysfunction, which predisposes to congenital male reproductive disorders (cryptorchidism, hypospadias). While the latter are considered to reflect impaired foetal androgen production, effects resulting from foetal growth impairment (FGI) are likely indirect. As FGI has numerous life-long health consequences, and is affected by maternal lifestyle, research into the origins of male reproductive disorders should take more account of this. Additionally, potential effects on foetal growth/foetal testis from the increasing use of medications in pregnancy deserves more research attention.

Seminal plasma S100A8/A9 as a potential biomarker of genital tract inflammation

ABSTRACT

Infections and inflammatory reactions in the male genital tract are the leading causes of male infertility with a prevalence of 6%-10%, primarily affecting testicular and epididymal function and ultimately compromising sperm quality. However, most infertile patients with genital infection/inflammation are asymptomatic and easily overlooked. Traditional indicators, including white blood cells, elastase, and other components in semen, can reflect inflammation of the genital tract, but there is still a lack of a uniform standard method of detection. Therefore, it is necessary to explore reliable markers in semen that reflect the inflammatory status of the genital tract. Using the experimental autoimmune orchitis (EAO) model to simulate noninfectious chronic orchitis, we successfully collected ejaculated seminal fluid from EAO rats using optimized electrical stimulation devices. Proteomic analysis was performed using isobaric tags for relative and absolute quantification (iTRAQ). Compared to the control group, 55 upregulated and 105 downregulated proteins were identified in seminal plasma samples from the EAO group. In a preliminary screening, the inflammation-related protein S100A8/A9 was upregulated. We further verified that S100A8/A9 was increased in seminal plasma and highly expressed in testicular macrophages of the EAO model. In patients with oligoasthenospermia and genital tract infections, we also found that S100A8/A9 levels were remarkably increased in seminal plasma and testicular macrophages. S100A8/A9 in semen may be a potential biomarker for chronic genital inflammation. Our study provides a new potential biomarker for early diagnosis and further understanding of male infertility caused by genital inflammation.

The relationship between semen quality in male infertility clinic patients and bisphenol A：A Chinese cross-sectional study

Bisphenol A (BPA) is a growing concern as an endocrine-disrupting chemical due to its adverse health effects. However, the association between BPA and sperm quality in adult human males remains unclear. The aim of this study was to assess the daily life exposure level of BPA and analyze its correlation with sperm quality in males. Patients who sought treatment in Chinese infertility clinics between May and October 2023 were selected as study subjects. We determined participants' serum BPA content using high-performance liquid chromatography. Sperm count and motility were assessed using a computer-aided sperm analysis system, while sperm morphology was analyzed using an improved Papanicolaou stain. A total of 405 participants, averaging 33.01 ± 5.44 years old, were included. We observed low semen quality among participants in infertility clinics. Principal component analysis was performed for each semen quality index, and three principal components reflecting sperm motility, count, and morphology were extracted. The participants' mean serum BPA level was 6.96 ng/mL. Negative correlations were observed between serum BPA content and total sperm count, sperm density, forward motility rate, and non-forward motility rate. A positive correlation was found between the non-motile sperm rate and the head deformity rate. Morphological abnormalities were the predominant adverse effects observed. Despite low daily life BPA exposure, long-term low-dose exposure in the general population may damage semen quality. This study provides a scientific basis for managing health risks associated with BPA exposure.

Longitudinal trends and correlation between autism spectrum disorder prevalence and sperm quality parameters (2000-2024): a comprehensive statistical analysis

Introduction

Over the past few decades, there has been growing concern about the concurrent trends of increasing Autism Spectrum Disorder (ASD) prevalence and declining sperm quality. These trends represent significant public health challenges that warrant thorough investigation of their underlying causes and implications.

Objectives

The primary objectives of this study are to analyze trends in ASD prevalence and sperm quality parameters from 2000 to 2024, assess the statistical significance and effect size of these trends, explore potential correlations between ASD prevalence and sperm quality parameters, and identify significant predictors among sperm quality parameters that influence ASD prevalence.

Methods

This study employed a longitudinal approach using multiple regression, time series analysis, ANOVA, Principal Component Analysis (PCA), hierarchical clustering, logistic regression, and cross-correlation analysis. Data on ASD prevalence were sourced from the CDC Autism and Developmental Disabilities Monitoring Network, while sperm quality data were collected from various published studies.

Results

The findings reveal significant negative associations between ASD prevalence and sperm quality parameters such as sperm concentration and motility, suggesting that better sperm quality is linked to lower ASD rates. Conversely, parameters like sperm DNA fragmentation (SDF), volume of ejaculate, pH level, and semen viscosity show positive associations with ASD prevalence, indicating higher values in these parameters correlate with higher ASD rates.

Conclusion

The study highlights the importance of maintaining reproductive health to potentially mitigate ASD risk and calls for further research to elucidate the underlying mechanisms driving these trends. These findings support the hypothesis that reproductive health factors play a crucial role in ASD etiology and suggest potential biological markers for assessing ASD risk.

Sperm concentration remains stable among fertile American men: a systematic review and meta-analysis

IMPORTANCE

Findings from several high profile meta-analyses have raised concerns about an ongoing global decline in sperm concentration and male fertility. However, these studies exhibit considerable heterogeneity in key variables including study population, methodology, fertility status, and geographic region.

OBJECTIVE

To perform a systematic review and meta-analysis exploring temporal trends in sperm concentration among fertile men and men unselected for fertility status in the United States.

DATA SOURCES

A literature search performed in Scopus and PubMed databases for studies published between 1970 and 2023. Additional studies were included from citations of prior global meta-analyses and reviews evaluating temporal trends in sperm count.

STUDY SELECTION AND SYNTHESIS

Studies were included if they presented original data on sperm concentration in US men without known infertility from 1970 to 2023. Aggregate data were assessed across all study populations, with additional subgroup analyses stratified by fertility status and US region.

MAIN OUTCOMES

Weighted generalized linear models were generated to evaluate the association between mean sperm concentration and sample collection year.

RESULTS

A total of 874 articles were screened, with 58 meeting the inclusion criteria. These represented 75 unique study populations totaling 11,787 men in the United States. Across all study populations, no change in sperm concentration was observed between 1970 and 2018 in unadjusted models (β = 0.14 million/mL per year). When adjusting for US region, no statistically significant decline in sperm concentration was seen. When adjusting for both region and fertility status, a modest annual decline was observed to meet statistical significance (β = -0.35 million/mL per year). Of the 49 study populations reporting adequate data to determine mean total sperm count, there was a significant increase in total sperm count of 2.9 million per year between 1970 and 2018. Subgroup analysis found no statistically significant change in mean sperm concentration among any US census region or fertility status cohort.

CONCLUSION AND RELEVANCE

In contrast to prior global studies, this analysis suggests no clinically significant decline in sperm concentration among confirmed fertile men and the general male US population without known infertility. Although these findings provide some reassurance against a widespread rapid decline, further studies are necessary to better understand this important topic.

Schisandrin B alleviates testicular inflammation and Sertoli cell apoptosis via AR-JNK pathway

Bacterial testicular inflammation is one of the important causes of male infertility. Using plant-derived compounds to overcome the side effects of antibiotics is an alternative treatment strategy for many diseases. Schizandrin B (SchB) is a bioactive compound of herbal medicine Schisandra chinensis which has multiple pharmacological effects. However its effect and the mechanism against testicular inflammation are unknown. Here we tackled these questions using models of lipopolysaccharide (LPS)-induced mice and -Sertoli cells (SCs). Histologically, SchB ameliorated the LPS-induced damages of the seminiferous epithelium and blood-testicular barrier, and reduced the production of pro-inflammatory mediators in mouse testes. Furthermore, SchB decreased the levels of pro-inflammatory mediators and inhibited the nuclear factor kB (NF-κB) and MAPK (especially JNK) signaling pathway phosphorylation in LPS-induced mSCs. The bioinformatics analysis based on receptor prediction and the molecular docking was further conducted. We targeted androgen receptor (AR) and illustrated that AR might bind with SchB in its function. Further experiments indicate that the AR expression was upregulated by LPS stimulation, while SchB treatment reversed this phenomenon; similarly, the expression of the JNK-related proteins and apoptotic-related protein were also reversed after AR activator treatment. Together, SchB mitigates LPS-induced inflammation and apoptosis by inhibiting the AR-JNK pathway.

Influence of male body mass index on semen analysis parameters and in vitro fertilization outcomes

Concurrent global increase of prevalence of obesity and male fertility implies link between overweight and obesity with male subfertility. This hypothesis is supported by numerous population-based epidemiological studies. Increase in body mass index (BMI) is associated with poor sperm quality in fertile, and more noticeable in infertile men. Nevertheless, some studies disprove damaging effect of BMI on semen quality. To examine the influence of men's BMI in infertile couples undergoing in vitro fertilization (IVF) on semen analysis parameters and IVF outcomes. Study encompassed all couples who underwent IVF at Gynecology and Obstetrics Clinic Narodni Front in Belgrade during 2018 and 2019. Exclusion criteria were azoospermia, conditions and diseases that could affect the semen analysis parameters (diabetes, malignant diseases treated with radiation and/or chemotherapy, trauma or surgery of the genital organs, mumps or undescended testicles in childhood). Evaluated semen analysis parameters included semen ejaculate volume, sperm pH, sperm count, sperm motility, and sperm morphology. IVF outcomes comprised total number of embryos, number and percentage of obtained good-quality embryos and clinical pregnancy rates. Based on BMI value, participants were divided into a group of underweight (Group 1), normally weight (Group 2), overweight (Group 3), and obese men (Group 4). After applying inclusion and exclusion criteria, 411 men (couples) were included in the analysis. The largest number of men were overweight, while the smallest belonged to the group of underweight participants. There are no significant differences in the semen analysis parameters between study groups. Correlation analysis shown weak and insignificant correlation between BMI and semen analysis parameters. The number and proportion of good quality embryos is significantly lower in overweight and obese study groups compared to normal weight and underweight groups (2.89, 2.91, 2.42, and 2.36, respectively, P = .041). The differences in other IVF outcomes: total number of embryos (3.61, 3.74, 3.21, and 3.37, respectively) and clinical pregnancy rates (41.26%, 43.09%, 42.78%, and 39.95%, respectively) between study groups were not significant (P > .05). BMI does not significantly affect semen analysis parameters, but a higher BMI is associated with a lower number and proportion of good quality embryos in IVF outcomes.

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.

Impact of chronic sleep deprivation on male reproductive health: Insights from testicular and epididymal responses in mice

BACKGROUND

Sleep deprivation (SD) can cause damage to the male reproductive system. However, the duration required for such damage and the specific sequence and severity of damage to the testis and epididymis remain unclear.

OBJECTIVE

To investigate the effects of different durations of SD on different parts of the testis and epididymis caput, corpus, and cauda.

METHODS

Adult ICR mice were randomly assigned to five groups: the SD group (SD for 18 h/day for 1, 2, 3, or 4 weeks), the SD + Vit E group (supplemented with Vit E 50 mg/kg/d during 4 weeks of SD, the SD+NS group (saline supplementation during 4 weeks of SD), the SD + RS group (5 weeks of recovery sleep after 4 weeks of SD), and a normal sleep control (Ctrl) group. Following the interventions, sperm parameters, testicular and epididymal histopathology, inflammatory response, and oxidative stress markers were compared between the groups.

RESULTS

Compared to the Ctrl group, the SD group showed a decrease in sperm motility and concentration from SD 2 W and SD 3 W, respectively. Decreases in sperm concentration and motility were more pronounced in the cauda compared to the caput and corpus. Pathological damage was less severe in the epididymis caput than in the corpus and cauda. After 4 weeks of SD, inflammation and oxidative stress increased in both testes and epididymis. Both sleep recovery and vitamin E supplementation showed significant improvements, though they did not fully reach the level of the Ctrl group.

CONCLUSION

Chronic SD for more than 2 weeks causes varying degrees of damage to the testis, epididymis caput, corpus, and cauda in male mice. This damage is not fully reversible after 5 weeks of sleep recovery and antioxidant stress treatment. These findings help us to identify and prevent SD damage to the male reproduction at an early stage.

Recent decline in sperm motility among donor candidates at a sperm bank in Denmark

STUDY QUESTION

Has there been variation in semen quality among men applying to be sperm donors (i.e. donor candidates) in Denmark in recent years (2017-2022)?

SUMMARY ANSWER

The motile sperm concentration and total motile sperm count (TMSC) in ejaculates-both measures of sperm quality-declined by as much as 22% from 2019 to 2022.

WHAT IS KNOWN ALREADY

Questions remain about whether human semen quality has declined in recent years. Whilst some studies provide evidence for a decline in human semen quality, these findings have been disputed owing to potential biases in the populations studied or in the methods used to measure semen quality. Resolution of this issue has important implications for human fertility, as well as for those involved in the recruitment of sperm donors for use in medically assisted reproduction.

STUDY DESIGN, SIZE, DURATION

We obtained data on the semen quality of ejaculates previously collected from 2017 to 2022 at sperm bank locations in four cities in Denmark: Aarhus, Aalborg, Copenhagen, and Odense. Our study focuses on the single semen samples provided by 6758 donor candidates aged between 18 and 45 years old to determine whether their sperm quality met a minimum criterion for them to be accepted as sperm donors.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All ejaculates were analyzed within 1 hour of production. Semen volume (ml) was estimated by weight and both the concentration (106/ml) of sperm as well as the concentration of motile sperm (World Health Organization grades a and b) were measured using the same protocols and computer-assisted semen analysis system across all years at each site. Statistical analyses of the semen variables were controlled for age and donation site, as well as the average monthly high temperature when the ejaculate was produced.

MAIN RESULTS AND THE ROLE OF CHANCE

From 2017 to 2019, semen volume, sperm concentration, and total sperm count in the ejaculates of donor candidates increased by 2-12%. Then, from 2019 to 2022, sperm concentration and total sperm count changed by 0.1-5% from year to year, but none of those changes were statistically significant. In contrast, both motile sperm concentration and TMSC declined significantly, by 16% and 22%, respectively, between 2019 and 2022. Thus, the concentration of motile sperm in donor candidates declined from 18.4 [95% CL: 17.0, 20.0] million/ml in 2019 to 15.5 [14.4, 16.7] million/ml in 2022, and TMSC declined from 61.4 [55.8, 67.5] million per ejaculate in 2019 to 48.1 [44.1, 52.4] million in 2022.

LIMITATIONS, REASONS FOR CAUTION

We cannot determine from the available data the causes of the decline in semen quality of donor candidates from 2019 to 2022. However, as this period coincides with lockdowns and changes in work patterns during the coronavirus disease 2019 pandemic, it is possible that changes in motile sperm concentration and TMSC were the result of changes in the lifestyles of the men whose semen was analyzed.

WIDER IMPLICATIONS OF THE FINDINGS

Men providing initial semen samples at sperm banks, when applying to be sperm donors, are a useful population in which to monitor changes in human semen quality over time. Our results have implications for human fertility and the recruitment of sperm donors for medically assisted reproduction, where motile sperm concentration is an essential selection criterion because it influences fertility. We suggest that gathering health and lifestyle data on donor candidates at sperm banks might help to identify causal factors for the decline of sperm quality that could be addressed and intervention, if desired, could be personalized for each accepted donor.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was obtained for this study. E.L. and A.-B.S. are employees of Cryos International. AP reports paid consultancy for Cryos International, Cytoswim Ltd, Exceed Health, and Merck Serono in the last 2 years of this study, but all monies were paid to the University of Sheffield (former employer). AP is also an unpaid trustee of the Progress Educational Trust (Charity Number 1139856). RM declares support from Cryos International to present results of this research at ESHRE 2023. None of the authors were directly involved in the collection or physical analysis of semen samples.

TRIAL REGISTRATION NUMBER

N/A.

The effects of radiofrequency exposure on male fertility: A systematic review of human observational studies with dose-response meta-analysis

BACKGROUND

The World Health Organization (WHO) is bringing together evidence on radiofrequency electromagnetic field (RF-EMF) exposure in relation to health outcomes, previously identified as priorities for research and evaluation by experts in the field, to inform exposure guidelines. A suite of systematic reviews have been undertaken by a network of topic experts and methodologists to collect, assess and synthesise data relevant to these guidelines. Following the WHO handbook for guideline development and the COSTER conduct guidelines, we systematically reviewed the evidence on the potential effects of RF-EMF exposure on male fertility in human observational studies.

METHODS

We conducted a broad and sensitive search for potentially relevant records within the following bibliographic databases: MEDLINE; Embase; Web of Science and EMF Portal. We also conducted searches of grey literature through relevant databases including OpenGrey, and organisational websites and consulted RF-EMF experts. We hand searched reference lists of included study records and for citations of these studies. We included quantitative human observational studies on the effect of RF-EMF exposure in adult male participants on infertility: sperm concentration; sperm morphology; sperm total motility; sperm progressive motility; total sperm count; and time to pregnancy. Titles and abstracts followed by full texts were screened in blinded duplicate against pre-set eligibility criteria with consensus input from a third reviewer as required. Data extraction from included studies was completed by two reviewers, as was risk of bias assessment using the Office of Health Assessment and Translation (OHAT) tool. We conducted a dose-response meta-analysis as possible and appropriate. Certainty of the evidence was assessed by two reviewers using the OHAT GRADE tool with input from a third reviewer as required.

RESULTS

We identified nine studies in this review; seven were general public studies (with the general public as the population of interest) and two were occupational studies (with specific workers/workforces as the population of interest). General public studies. Duration of phone use: The evidence is very uncertain surrounding the effects of RF-EMF on sperm concentration (10/6 mL) (MD (mean difference) per hour of daily phone use 1.6 106/mL, 95 % CI -1.7 to 4.9; 3 studies), sperm morphology (MD 0.15 percentage points of deviation of normal forms per hour, 95 % CI -0.21 to 0.51; 3 studies), sperm progressive motility (MD -0.46 percentage points per hour, 95 % CI -1.04 to 0.13; 2 studies) and total sperm count (MD per hour -0.44 106/ejaculate, 95 % CI -2.59 to 1.7; 2 studies) due to very low-certainty evidence. Four additional studies reported on the effect of mobile phone use on sperm motility but were unsuitable for pooling; only one of these studies identified a statistically significant effect. All four studies were at risk of exposure characterisation and selection bias; two of confounding, selective reporting and attrition bias; three of outcome assessment bias and one used an inappropriate statistical method. Position of phone: There may be no or little effect of carrying a mobile phone in the front pocket on sperm concentration, total count, morphology, progressive motility or on time to pregnancy. Of three studies reporting on the effect of mobile phone location on sperm total motility and, or, total motile count, one showed a statistically significant effect. All three studies were at risk of exposure characterisation and selection bias; two of confounding, selective reporting and attrition bias; three of outcome assessment bias and one used inappropriate statistical method. RF-EMF Source: One study indicates there may be little or no effect of computer or other electric device use on sperm concentration, total motility or total count. This study is at probably high risk of exposure characterisation bias and outcome assessment bias. Occupational studies. With only two studies of occupational exposure to RF-EMF and heterogeneity in the population and exposure source (technicians exposed to microwaves or seamen exposed to radar equipment), it was not plausible to statistically pool findings. One study was at probably or definitely high risk of bias across all domains, the other across domains for exposure characterisation bias, outcome assessment bias and confounding.

DISCUSSION

The majority of evidence identified was assessing localised RF-EMF exposure from mobile phone use on male fertility with few studies assessing the impact of phone position. Overall, the evidence identified is very uncertain about the effect of RF-EMF exposure from mobile phones on sperm outcomes. One study assessed the impact of other RF-EMF sources on male fertility amongst the general public and two studies assessed the impact of RF-EMF exposure in occupational cohorts from different sources (radar or microwave) on male fertility. Further prospective studies conducted with greater rigour (in particular, improved accuracy of exposure measurement and appropriate statistical method use) would build the existing evidence base and are required to have greater certainty in any potential effects of RF-EMF on male reproductive outcomes. Prospero Registration: CRD42021265401 (SR3A).

Impact of Climate Change on Reproductive Health and Pregnancy Outcomes: A Systematic Review

Climate change has emerged as a significant global health challenge, with growing evidence linking environmental factors to adverse reproductive health outcomes. The primary objective of this review is to assess the effects of climate change-driven environmental factors, such as air pollution and temperature extremes, on reproductive health outcomes, including fertility rates, miscarriage, preterm birth, and congenital anomalies. A comprehensive search of PubMed, Google Scholar, and Web of Science was conducted until July 2024. Studies included in the review were observational, experimental, and randomized controlled trials that reported quantitative data on reproductive outcomes in relation to climate-related environmental exposures. A total of 49 studies were selected for qualitative synthesis. The review found that increased exposure to particulate matter (PM2.5), extreme temperatures, and proximity to traffic were consistently associated with reduced fertility, increased risks of miscarriage, preterm birth, and low birth weight. Adverse effects were particularly pronounced among vulnerable populations, such as pregnant women of lower socioeconomic status and those living in disaster-prone areas. The studies also highlighted potential transgenerational effects, with prenatal exposure to environmental stressors influencing the long-term health of offspring. The findings underscore the urgent need for public health interventions and policies to mitigate environmental exposures that negatively impact reproductive health. Future research should focus on longitudinal and interventional studies to establish causal relationships and inform effective public health strategies.

Thiacloprid impairs reproductive functions of male Wistar rats

Global male infertility correlated to the rise of endocrine-disrupting chemicals, including insecticides, has grown into a pressing problem. Thiacloprid is one of the most commonly used neonicotinoids that accounts for more than 25% of the global pesticide industry. However, its impact on the reproductive system and male fertility has not been fully elucidated. The object of this study was to explore the adverse effects of thiacloprid on male Wistar rats' reproductive system. Thirty healthy male rats were separated into one of three groups: control group, and two groups that were orally administered with low (22.5 mg/kg) and high dose (62.1 mg/kg) of thiacloprid for 56 days. Thiacloprid significantly (p<0.05) reduced body weight and relative testicular weight, as well as sperm quality (count, motility, viability, and morphology), in a dose-dependent manner. THIA-treated groups revealed a large effect (d > 0.8) on semen quality with Cohen's d of (6.57, 8.82), (20.14, 23.54), and (2.81, 9.10) for count, motility, and viability respectively. Meanwhile, the serum testosterone level dropped while the levels of luteinizing and follicle-stimulating hormones increased. 17ꞵ-hydroxy steroid dehydrogenase and 3ꞵ-hydroxy steroid dehydrogenase levels were significantly decreased in a dose-dependent manner. The activity of the tested antioxidant enzymes catalase (CAT), glutathione reduced (GSH), and superoxide dismutase (SOD) exhibited a considerable decrease compared to the control group with a significant elevation in the lipid peroxidation activity as indicated by malondialdehyde (MDA) level. The testicular histology revealed degenerative changes in spermatogenic cells and interstitial tissue. Comet assay revealed DNA fragmentation in treated groups' testicular tissue. Thiacloprid exposure interferes with reproductive function and impairs male Wistar rat fertility. Such harmful consequences may also develop in humans frequently exposed to thiacloprid.

IMPACT OF REAL-LIFE ENVIRONMENTAL EXPOSURES ON REPRODUCTION: Biosolids and male reproduction

Over the past 50 years, there has been a concerning decline in male reproductive health and an increase in male infertility which is now recognised as a major health concern globally. While male infertility can be linked to some genetic and lifestyle factors, these do not fully explain the rate of declining male reproductive health. Increasing evidence from human and animal studies suggests that exposure to chemicals found ubiquitously in the environment may in part play a role. Many studies on chemical exposure, however, have assessed the effects of exposure to individual environmental chemicals (ECs), usually at levels not relevant to everyday human exposure. There is a need for study models which reflect the 'real-life' nature of EC exposure. One such model is the biosolids-treated pasture (BTP) sheep model which utilises biosolids application to agricultural land to examine the effects of exposure to low-level mixtures of chemicals. Biosolids are the by-product of the treatment of wastewater from industrial and domestic sources and so their composition is reflective of the ECs to which humans are exposed. Over the last 20 years, the BTP sheep model has published multiple effects on offspring physiology including consistent effects on the male reproductive system in fetal, neonatal, juvenile, and adult offspring. This review focuses on the evidence from these studies which strongly suggests that low-level EC exposure during gestation can alter several components of the male reproductive system and highlights the BTP model as a more relevant model to study real-life EC exposure effects.

Innovative Approach for Human Semen Quality Assessment Based on Volatilomics

The volatilome profile of some biofluids (blood, urine, and human semen) identified by Solid-Phase Microextraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS) and collected from young men living in two high-pollution areas in Italy, i.e., Land of Fires and Valley of Sacco River, have been coupled to sperm parameters obtained by spermiogram analysis to build general multiple regression models. Panels of volatile organic compounds (VOCs) have been selected to optimize the models and used as predictive variables to estimate the different sperm quality parameters (sperm cell concentration, total and progressive motility/immotile cells, total/head/neck/tail morphology anomalies, semen round cell concentration). The results of the multiple linear regression models based on the different subgroups of data joining VOCs from one/two or three biofluids have been compared. Surprisingly, the models based on blood and urine VOCs have allowed an excellent estimate of spermiogram values, paving the way towards a new method of indirect evaluation of semen quality and preventive screening. The significance of VOCs in terms of toxicity and dangerousness was discussed with the support of chemical databases available online.

Metabolomics analysis of human spermatozoa reveals impaired metabolic pathways in asthenozoospermia

BACKGROUND

Infertility is a major health issue, affecting 15% of reproductive-age couples with male factors contributing to 50% of cases. Asthenozoospermia (AS), or low sperm motility, is a common cause of male infertility with complex aetiology, involving genetic and metabolic alterations, inflammation and oxidative stress. However, the molecular mechanisms behind low motility are unclear. In this study, we used a metabolomics approach to identify metabolic biomarkers and pathways involved in sperm motility.

METHODS

We compared the metabolome and lipidome of spermatozoa of men with normozoospermia (n = 44) and AS (n = 22) using untargeted LC-MS and the metabolome of seminal fluid using 1H-NMR. Additionally, we evaluated the seminal fluid redox status to assess the oxidative stress in the ejaculate.

RESULTS

We identified 112 metabolites and 209 lipids in spermatozoa and 27 metabolites in the seminal fluid of normozoospermic and asthenozoospermic men. PCA analysis of the spermatozoa's metabolomics and lipidomics data showed a clear separation between groups. Spermatozoa of asthenozoospermic men presented lower levels of several amino acids, and increased levels of energetic substrates and lysophospholipids. However, the metabolome and redox status of the seminal fluid was not altered inAS.

CONCLUSIONS

Our results indicate impaired metabolic pathways associated with redox homeostasis and amino acid, energy and lipid metabolism in AS. Taken together, these findings suggest that the metabolome and lipidome of human spermatozoa are key factors influencing their motility and that oxidative stress exposure during spermatogenesis or sperm maturation may be in the aetiology of decreased motility in AS.

Downward trend in male reproductive health and fertility in Eastern Iran

This study aimed to assess the ten-year trend in semen quality among couples referred to the Infertility Center in Kerman between 2008 and 2017. The study included 2952 semen samples from men 18 to 60 years old referred to the infertility center as infertile couples living in Kerman province, Iran, whether they had normal or abnormal semen analysis. A total of 2952 sperm samples were included. Statistically significant changes were observed in semen parameters. Particularly, significant changes were observed for volume (-0.08 mL/year), sperm concentration (-2.34 (mio/mL)/year), total sperm count (-13.17 (mio/ejaculate)/year), progressive motility (-2.62%/year), non-progressive motility (-0.59%/year), immotile sperm (2.49%/year), and normal morphology (-0.134%/year). In bivariate analysis, the prevalence of oligozoospermia in this study showed a statistically significant association with age (OR = 1.019; 95% CI = 1.007-1.032; p = 0.003). Likewise, there was a statistically significant association with the year (OR = 1.087; 95% CI = 1.050-1.125; p = 0.000). Semen quality parameters showed a downtrend during the last 10 years in this study, emphasizing the importance of male reproductive health monitoring and warning public health coordinators to pay more attention to this important issue.

The effect of Chinese herbal medicine on male factor infertility: study protocol for a randomized controlled trial

Background

The global prevalence of infertility is 9%, with male factors potentially accounting for 40% to 60% of cases. Conventional treatments can be ineffective, invasive, costly, and linked to adverse effects and high risks. Previous studies have shown that, Chinese herbal medicine (CHM) can regulate the hypothalamus-pituitary-testis axis, improve sperm abnormalities and quality, mitigate oxidative stress, and decrease DNA fragmentation index (DFI). Yet, the evidence backing the use of Chinese herbal medicine (CHM) for treating male factor infertility lacks conviction due to study design limitations, and there remains a scarcity of studies on the live birth rate following CHM treatment for male factor infertility. Here, we describe the rationale and design of a randomized waitlist-controlled trial to evaluate the effect of CHM on the live birth rate among males with infertility.

Methods

This study is a single-center, randomized, waitlist-controlled study. A total of 250 couples diagnosed with male factor infertility will be enrolled in this study and then randomly allocated into two groups in a 1:1 ratio. Male participants in CHM group (treatment group) will receive CHM once a day for 3 months. Male participants in the waitlist group (control group) will not receive any treatment for 3 months. After 3 months, participants in both groups need to be followed up for another 12 months. The primary outcome will be the live birth rate; secondary outcomes include semen quality parameters, DFI and pregnancy related outcomes. Safety will also be assessed.

Discussion

The purpose of this trial is to explore the effects and safety of CHM on the live birth rate among couples dealing with male factor infertility. The outcome of this trial may provide a viable treatment option for male factor infertility.

Trial registration

Chinese Clinical Trial Registry: ChiCTR2200064416. Registered on 7 October 2022, https://www.chictr.org.cn.

The use of time-dynamic patterns of temperature and flexible generalized models to clarify the relations between temperature and semen quality

BACKGROUND

Sperm quality has decreased over the last decades worldwide. It is affected, among others, by season and heat. This study aimed to address the association between ambient temperature and sperm quality by assessing its shape using flexible multivariate models and identifying distinct time-dynamic patterns of temperature change based on unsupervised analysis.

MATERIAL AND METHODS

A retrospective population-based study has been conducted, including all samples of males attending the Fertility and In-Vitro-Fertilization unit at a single medical center during 2016-2022. Flexible generalized models were fitted to characterize the relations between sperm quality and temperature while accounting for patients characteristics, and to identify temperature levels that correspond with the optimal sperm quality. This information was then used to estimate adjusted slope coefficients at specified time-windows.

RESULTS

In total, 4555 sperm samples were provided by 3229 individuals. Sperm concentration, motility and progressive motility were higher by 8 %, 11 % and 16 %, respectively, during the spring versus the fall season. Furthermore, their quality during early spermatogenesis improved with temperature, until a certain optimum around 23 °C-24 °C. Increasing temperature at later developmental stages was associated with lower sperm concentration and higher motility. Sperm concentration and motility were highest following a period of moderate gradual warming. Motility was higher and sperm concentration was lower, following a period with heatwaves or summer.

CONCLUSIONS

This study assessed temperature role in sperm production quality by considering both average and time-dynamic temperatures. It identified several temperature change patterns over time and stratified the analysis by them. The differences in the relations across stages of spermatogenesis were addressed. Several mechanisms may explain the associations found, including heat-induced apoptosis of the sperm cells, and destruction of sperm cells DNA integrity by over-production of reactive oxygen species. The gradual global warming necessitates exploration of individual response to outdoor temperature in relations to genetic predisposition, lifestyle, and other health characteristics.

Oral exposure to phenanthrene during gestation disorders endocrine and spermatogenesis in F1 adult male mice

Phenanthrene (Phe), a typical low-molecular-weight polycyclic aromatic hydrocarbon (PAH) of three benzene rings, is one of the most abundant PAHs detected in daily diets. Pregnant women and infants are at great risk of Phe exposure. In the present study, Phe was administered to pregnant mice at a dose of 0, 60, or 600 μg/kg body weight six times, and the F1 male mice showed significant reproductive disorders: the testicular weight and testis somatic index were significantly reduced; the levels of serum testosterone, GnRH and SHBG were increased, while the FSH levels were reduced; histological analysis showed that the amount of Sertoli cells and primary spermatocytes in seminiferous tubules was increased, while the amount of secondary spermatocytes and spermatids were decreased in Phe groups. The protein levels of PCNA and androgen receptor were reduced. Differently expressed genes in the testis screened by RNA sequence were enriched in antioxidant capacity, reproduction et al.. Further biochemical tests confirmed that the antioxidant capacity in the F1 testis was significantly inhibited by treatment with Phe during pregnancy. Those results suggested that gestational Phe exposure disordered hypothalamic-pituitary-gonadal (HPG) hormones on the one hand, and on the other hand reduced testicular antioxidant capacity and further arrested cell cycle in F1 adult male mice, which co-caused the inhibition of spermatogenesis.

Ursolic acid attenuates oligospermia in busulfan-induced mice by promoting motor proteins

Background

Oligospermia is one of the most common reasons for male infertility which is troubling numerous couples of child-bearing age. This investigation scrutinizes the implications and mechanistic underpinnings of ursolic acid's effect on busulfan-induced oligospermia in mouse models.

Methods

A singular intraperitoneal injection of busulfan at a dosage of 30 mg/kg induced oligospermia. Two weeks subsequent to this induction, mice were subjected to various dosages of ursolic acid (10, 30, and 50 mg/kg body weight, respectively) on a daily basis for four consecutive weeks. Following this treatment period, a meticulous analysis of epididymal sperm parameters, encompassing concentration and motility, was conducted using a computer-assisted sperm analysis system. The histopathology of the mice testes was performed utilizing hematoxylin and eosin staining, and the cytoskeleton regeneration of the testicular tissues was analyzed via immunofluorescent staining. Serum hormone levels, including testosterone, luteinizing hormone, and follicle-stimulating hormone, as well as reactive oxygen species levels (inclusive of reactive oxygen species and malondialdehyde), were gauged employing specific enzyme-linked immunosorbent assay kits. Differentially expressed genes of testicular mRNA between the oligospermia-induced group and the various ursolic acid treatment groups were identified through RNA sequencing analysis.

Results

The results revealed that a dosage of 50 mg/kg ursolic acid treatment could increase the concentration of epididymal sperm in oligospermia mice, promote the recovery of testicular morphology, regulate hormone levels and ameliorate oxidative damage. The mechanism research results indicated that ursolic acid increased the expression level of genes related to motor proteins in oligospermia mice.

Effect of Advanced Glycation end Products (AGEs) on Sperm Parameters and Function in C57Bl/6 Mice

This study investigated the deleterious impact of advanced glycation end products (AGEs), commonly present in metabolic disorders like diabetes, obesity, and infertility-related conditions, on sperm structure and function using a mouse model where AGE generation was heightened through dietary intervention. Five-week-old C57BL/6 mice were divided into two groups, one on a regular diet (control) and the other on an AGE-rich diet. After 13 weeks, various parameters were examined, including fasting blood glucose, body weight, food consumption, sperm parameters and function, testicular superoxide dismutase levels, malondialdehyde content, total antioxidant capacity, Johnson score, AGE receptor (RAGE) content, and carboxymethyl lysine (CML) content. The results showed that mice in the AGE group exhibited increased body weight and elevated fasting blood glucose levels. Furthermore, the AGE group displayed adverse effects on sperm, including reduced sperm counts, motility, increased morphological abnormalities, residual histone, protamine deficiency, sperm DNA fragmentation, reduced testicular antioxidant capacity, and higher levels of RAGE and CML proteins. These findings underscore the negative impact of AGEs on male reproductive health, particularly within the context of metabolic disorders, emphasizing the crucial role of the AGE/RAGE axis in male infertility, especially in the context of Western dietary patterns.

Sleep duration and biomarkers of fecundity in young men: a cross-sectional study from a population-based cohort

BACKGROUND

Poor male fecundity is of concern and warrants the identification of potential modifiable risk factors. Short and long sleep duration might be risk factors for poor male fecundity although evidence in this research field is inconsistent.

OBJECTIVES

To investigate the association between sleep duration and biomarkers of male fecundity in young men.

MATERIALS AND METHODS

We conducted a cross-sectional study of 1,055 young men from the Fetal Programming of Semen Quality (FEPOS) cohort, Denmark, 2017-2019. Sleep duration was obtained from an online survey answered by the participants prior to the clinical visit, where semen and blood samples were obtained, and testis volume was self-assessed using an Orchidometer. Percentage differences in semen characteristics, testes volume, and reproductive hormone levels were analysed according to sleep duration using multivariable negative binomial regression models. Sleep duration was dichotomised (recommended (6-9 h/night) versus deviant sleep) and visualised continuously as restricted cubic spline plots.

RESULTS

Deviation from recommended sleep duration was associated with higher high DNA stainability (HDS) of 5% (95% CI: -1%; 13%), higher testosterone of 3% (95% CI: 0%; 7%) and higher free androgen index (FAI) of 6% (95% CI: 0%; 13%). The spline plots overall supported these results, suggesting u-shaped associations between sleep duration and HDS, testosterone and FAI, a linear association between sleep duration and semen volume and sex hormone binding globulin (SHBG) and an inverse u-shaped association with normal morphology.

DISCUSSION

Information on sleep duration was obtained by self-report in broad categories with at least 3 h intervals. We were not able to investigate short or long sleep duration separately, since only few participants reported this.

CONCLUSION

Sleep duration was associated with some biomarkers of fecundity in young men. Maintaining a recommended sleep duration may thus be beneficial for young men with regard to reproductive health.

Management of Male Infertility with Coexisting Sexual Dysfunction: A Consensus Statement and Clinical Recommendations from the Asia-Pacific Society of Sexual Medicine (APSSM) and the Asian Society of Men's Health and Aging (ASMHA)

Male infertility (MI) and male sexual dysfunction (MSD) can often coexist together due to various interplay factors such as psychosexual, sociocultural and relationship dynamics. The presence of each form of MSD can adversely impact male reproduction and treatment strategies will need to be individualized based on patients' factors, local expertise, and geographical socioeconomic status. The Asia Pacific Society of Sexual Medicine (APSSM) and the Asian Society of Men's Health and Aging (ASMHA) aim to provide a consensus statement and practical set of clinical recommendations based on current evidence to guide clinicians in the management of MI and MSD within the Asia-Pacific (AP) region. A comprehensive, narrative review of the literature was performed to identify the various forms of MSD and their association with MI. MEDLINE and EMBASE databases were searched for the following English language articles under the following terms: "low libido", "erectile dysfunction", "ejaculatory dysfunction", "premature ejaculation", "retrograde ejaculation", "delayed ejaculation", "anejaculation", and "orgasmic dysfunction" between January 2001 to June 2022 with emphasis on published guidelines endorsed by various organizations. This APSSM consensus committee panel evaluated and provided evidence-based recommendations on MI and clinically relevant MSD areas using a modified Delphi method by the panel and specific emphasis on locoregional socio-economic-cultural issues relevant to the AP region. While variations exist in treatment strategies for managing MI and MSD due to geographical expertise, locoregional resources, and sociocultural factors, the panel agreed that comprehensive fertility evaluation with a multidisciplinary management approach to each MSD domain is recommended. It is important to address individual MI issues with an emphasis on improving spermatogenesis and facilitating reproductive avenues while at the same time, managing various MSD conditions with evidence-based treatments. All therapeutic options should be discussed and implemented based on the patient's individual needs, beliefs and preferences while incorporating locoregional expertise and available resources.

Illegal Use of Testosterone and Other Anabolic-Androgenic Steroids in the Population of Amateur Athletes in Wrocław, Poland-An Unfavorable Lifestyle Trend in the Population of Men of Reproductive Age

Background: One factor that may negatively impact male reproductive health is the illegal use of testosterone and anabolic-androgenic steroids. This study aimed to evaluate the prevalence of testosterone use in recreational athletes, as well as factors associated with its use, and to determine the profile of a person using testosterone. Methods: A cross-sectional analysis of data from an anonymous, online questionnaire of men recruited from gyms, randomly selected in Wrocław, Poland, has been performed. The minimal sample size was evaluated with the univariate logistic regression model. The association between testosterone use and other factors was also evaluated with the univariate logistic regression model. Results: A total of 35% of respondents used testosterone. The main purposes of testosterone use were the improvement of training effects and the improvement of body shape. The respondents most likely to use testosterone and other anabolic-androgenic steroids were men aged 26-35, whose earnings were at the level of the middle class or higher, who were married, had children, had training experience of at least 6 months, exercised at least once a week, took part in weightlifting competitions, were managers in a corporation or enterprise, or were self-employed. Most of the people using testosterone had self-treated side effects. Conclusions: The profile of the person most likely to use testosterone corresponds to the characteristics of men in optimal socio-demographic conditions for reproduction. These results indicate that this is a significant social problem that may impact male reproductive health.

Oxidative Stress-Associated Male Infertility: Current Diagnostic and Therapeutic Approaches

Infertility is a prevalent global issue affecting approximately 17.5% of adults, with sole male factor contributing to 20-30% of cases. Oxidative stress (OS) is a critical factor in male infertility, disrupting the balance between reactive oxygen species (ROS) and antioxidants. This imbalance detrimentally affects sperm function and viability, ultimately impairing fertility. OS also triggers molecular changes in sperm, including DNA damage, lipid peroxidation, and alterations in protein expression, further compromising sperm functionality and potential fertilization. Diagnostic tools discussed in this review offer insights into OS markers, antioxidant levels, and intracellular ROS concentrations. By accurately assessing these parameters, clinicians can diagnose male infertility more effectively and thus tailor treatment plans to individual patients. Additionally, this review explores various treatment options for males with OS-associated infertility, such as empirical drugs, antioxidants, nanoantioxidants, and lifestyle modifications. By addressing the root causes of male infertility and implementing targeted interventions, clinicians can optimize treatment outcomes and enhance the chances of conception for couples struggling with infertility.

Effects of environmental temperature extremes exposure on sperm quality - evidence from a prospective cohort study in Anhui Province, China

Extreme weather is becoming more frequent due to drastic changes in the climate. Despite this, the body of research focused on the association between temperature extreme events and sperm quality remains sparse. In this study, we elucidate the impact of exposure to environmental temperature extremes on sperm quality. Data for this investigation were derived from the Anhui Prospective Assisted Reproduction Cohort, encompassing the period from 2015 to 2020. Parameters such as sperm concentration, total sperm count, total motility, progressive motility, total motile sperm count, and progressive motile sperm count were quantified from semen samples. We assessed the exposure of participants to temperature extremes during the 0-90 days prior to sampling. This investigation encompassed 15,112 participants, yielding 28,267 semen samples. Our research findings indicate that exposure to low temperature extreme for three consecutive days (at the first percentile threshold) has a detrimental correlation with sperm count parameters and concentration. Similar trends were observed with the second percentile threshold, where significant adverse effects typically manifested after a four-day exposure sequence. Analysis of high temperature extreme showed that exposure at the 98th percentile had adverse effects on all six sperm quality parameters, and the sperm count parameter was particularly sensitive to high temperature, showing significant results immediately after three days of exposure. When considering even more temperature extreme (99th percentile), the negative consequences were more pronounced on the sperm count parameter. Additionally, progressive motility showed a stronger negative response. In summary, parameters associated with sperm count are particularly vulnerable to temperature extremes exposure. Exposure to high temperature extremes environments may also be associated with a decrease in sperm concentration and vitality. The findings of this study suggest that male population should pay attention to avoid exposure to temperature extreme environment, which has important significance for improving the quality of human fertility.

Nutritional aphrodisiacs: Biochemistry and Pharmacology

In 2022, the global prevalence of erectile dysfunction (ED) was estimated to be at least 150 million cases. This number is greatly suspected to be underestimate as most men withhold information about ED. Also, about 15% of world population have infertility troubles, and male factors are responsible for almost half of these cases. Studies have shown that the quality of semen has decreased in the past several decades owing to various health factors and environmental toxicants. The current medical interventions involve the inhibition of phosphodiesterase 5 which suffer from serious side effects and costly. One of the popular and most sought interventions are the natural and nutritional remedies as they are foods in essence and potentially with no harm to the body. Therefore, the goal of this paper is to provide a review of the most common nutritional aphrodisiacs with increasing libido and fertility highlighting the potential active constituents as well as the underlying mechanisms.

Changes in Sperm Parameters with Time in Men with Normal and Abnormal Baseline Semen Analysis

The association between paternal age and sperm quality in the population level has been previously studied. Only limited data exists regarding the intra-personal variations in semen parameters among fertile and infertile men over time. We aimed to assess trends over time in semen parameters among men with normal and abnormal baseline sperm parameters and investigate potential risk factors for sperm quality deterioration. This retrospective cohort study was conducted at a university-affiliated medical center in vitro fertilization (IVF) unit. Patients with at least two semen analyses (SA) performed > 1 year apart, with the last SA done between 2017 and 2021, were included. The study consisted of two main analyses-comparison of intra-patient's sperm parameters changes in men with normal and abnormal baseline SA (BSA) and analysis of risk factors for developing abnormal semen parameters over time in men who had normal BSA parameters. This study included a total of 902 men assessed for infertility with normal and abnormal BSA. The average time interval between tests was 1015 days (range 366-7709 days). Among individuals with normal BSA, there was a mild decline in most parameters-concentration (- 6.53 M/ml), motility (- 7.74%), and total motile count (TMC) (- 21.80 M) (p < 0.05 for all parameters). In contrast, a slight improvement in most parameters, except for concentration, was noted in men with abnormal BSA-volume (+ 0.21 ml), motility (+ 8.72%), and TMC (+ 14.38 M) (p < 0.05 for all parameters). Focusing on men with normal BSA, 33.5% of individuals developed abnormality in one or more of their sperm parameters over time, within a mean time of 1013 ± 661 days. We also found that only time between tests emerged as an independent prognostic factor for the development of abnormal SA later. Interestingly, sperm deterioration in participants in their third, fourth, and fifth decades of life with normal initial semen analysis was similar. Our study provides evidence of a decline in semen quality over time in individuals with normal BSA, in contrast to men with abnormal BSA. Longer time intervals between tests independently increase the risk of sperm abnormalities.

Histopathological evaluation of infertility: Lessons from laboratory rodents

Infertility is a growing challenge globally with emerging risk factors. There are effective laboratory tests to evaluate infertility in humans, nevertheless, some measures, especially histopathological evaluations, are invasive due to the pain inflicted when accessing the reproductive organs and obtaining samples; hence, their relevance may be limited in humans. However, these histopathological evaluations provide essential information on the etiopathogenesis of infertility and the likely mechanisms of action of potential therapeutic candidates. Also, non-invasive methods are available, such as the assay of testosterone in the blood and semen analysis, both of which are predictors of testicular functions. This review provides detailed information on the available histopathological investigations of infertility, such as qualitative and quantitative histopathological assessments of gonadal tissues, specific cell counts, and sperm morphology characterization, with a focus on the procedures, interpretation, and pathophysiological basis. Data from the literature revealed that histopathological examinations of the reproductive organs, as well as spermatozoa, are useful in understanding the pathogenesis of incident infertility. Histopathological evaluation may range from basic hematoxylin and eosin stains to some special stains. Also, histopathological findings (such as spermatogenic cells and planimetric variables, like seminiferous tubule diameter and theca cell and corpus luteum thickness) may be quantified and analyzed for comparison. Some skill is required for these investigations, which may be a limiting factor; however, they are important tools in translational medicine.

Hormone Regulation in Testicular Development and Function

The testes serve as the primary source of androgens and the site of spermatogenesis, with their development and function governed by hormonal actions via endocrine and paracrine pathways. Male fertility hinges on the availability of testosterone, a cornerstone of spermatogenesis, while follicle-stimulating hormone (FSH) signaling is indispensable for the proliferation, differentiation, and proper functioning of Sertoli and germ cells. This review covers the research on how androgens, FSH, and other hormones support processes crucial for male fertility in the testis and reproductive tract. These hormones are regulated by the hypothalamic-pituitary-gonad (HPG) axis, which is either quiescent or activated at different stages of the life course, and the regulation of the axis is crucial for the development and normal function of the male reproductive system. Hormonal imbalances, whether due to genetic predispositions or environmental influences, leading to hypogonadism or hypergonadism, can precipitate reproductive disorders. Investigating the regulatory network and molecular mechanisms involved in testicular development and spermatogenesis is instrumental in developing new therapeutic methods, drugs, and male hormonal contraceptives.

Associations between seminal plasma metals/metalloids and semen quality: A cross-sectional study

Exposure to metals/metalloids is reported to potentially influence semen quality. While most studies have focused on single metal impacts, the link between exposure to multiple metals and semen quality has remained less explored. The study aimed to investigate the effects of both individual and mixed metal/metalloid exposure on semen quality. A total of 330 men were recruited from three reproductive centers in eastern China. Seminal plasma levels of 25 metals/metalloids and sperm parameters were determined. We used the Generalized Linear Model (GLM) and Restricted Cubic Spline (RCS) to assess the relationships between single metals/metalloids and semen quality. The weighted quantile sum (WQS) models were then applied to evaluate the combined effect of all these metals/metalloids. We observed positive associations of exposure to lithium (Li), zinc (Zn), and magnesium (Mg) with an increased risk of below reference values for progressive motility and total motility using a logistic regression model (P < 0.05). Additionally, our results also revealed a significant inverse relationship between aluminum (Al) and both sperm concentration and count, while cobalt (Co) demonstrated a positive association with sperm concentration (P < 0.05). Notably, the WQS model indicated a significant positive association between exposure to metal/metalloid mixtures and the risk of abnormal progressive motility (OR: 1.57; 95%CI: 1.10, 2.24) and abnormal total motility (OR: 1.53; 95%CI: 1.06, 2.19), with this association primarily driven by Li, Mg, and Zn. In summary, our findings indicate that exposure to metal/metalloid mixtures might have an adverse effect on semen quality.