Effect of environmental contaminants on spermatogenesis

The influence and mechanisms of exogenous aryl hydrocarbon receptor ligands on the viability of mouse germ cells

Environmental pollution is a significant contributor to male infertility. Numerous environmental pollutants, such as PCB118, act as exogenous ligands for the aryl hydrocarbon receptor (AhR). However, the role of AhR in mediating the effects of environmental pollutants on male reproductive functions remains inadequately understood. In the present study, we assessed the viability of GC-1 and GC-2 cells using the CCK-8 assay. Immunofluorescence and Western blotting techniques were employed to investigate the distribution and protein expression levels of AhR within these cell lines. Alterations in reactive oxygen species (ROS) levels and mitochondrial membrane potential (MMP) were evaluated using DCFH-DA dye and the JC-1 assay, respectively. Furthermore, we investigated changes in the expression levels of Nrf2, Cleaved-Caspase 3, Cleaved-Caspase 8, Bcl-2, and Bax through Western blot analysis. Our findings indicate that PCB118 and the AhR-specific agonist CAY10465 diminish the viability of GC-1 and GC-2 cells, facilitate the nuclear translocation and expression of AhR protein, elevate ROS levels, and reduce MMP. Moreover, these agents markedly increase the levels of Cleaved-Caspase 3 and Cleaved-Caspase 8 while decreasing the Bax/Bcl-2 ratio. Notably, the AhR antagonist CH223191 and resveratrol have the capacity to restore the functionality of GC-1 and GC-2 cells by mitigating the effects of PCB118 and CAY10465. Based on these observations, we propose that exogenous AhR ligands PCB118 and CAY10465 promote the nuclear translocation and upregulation of AhR expression in GC-1 and GC-2 cells. This process subsequently induces mitochondrial oxidative stress, wich activates the apoptotic signaling pathway and ultimately compromises cellular viability.

Environmental toxicant 2,3,7,8-tetrachlorodibenzo-p-dioxin induces non-obstructive azoospermia: New insights from network toxicology, integrated machine learning, and biomolecular modeling

OBJECTIVE

As industrial pollution intensifies, global male semen quality has been declining at a rate of 2.64 % per year in the 21st century. Among the various types of infertility, non-obstructive azoospermia (NOA) is the most severe and is closely associated with exposure to environmental toxins. The molecular mechanisms by which 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a typical persistent organic pollutant, induces NOA have yet to be systematically elucidated.

METHODS

This study employed the single-sample Gene Set Enrichment Analysis (ssGSEA) method to identify key toxicological pathways and constructed a diagnostic model based on 113 machine learning algorithms. By integrating Weighted Gene Co-expression Network Analysis (WGCNA) and single-cell analysis, we identified hub genes associated with the Sertoli Cell-Only Syndrome (SCOS) subtype. Finally, biomolecular modeling was conducted to validate the binding efficacy of the hub genes with TCDD.

RESULTS

Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis based on the ssGSEA method indicated that TCDD may disrupt spermatogenesis by activating the Tumor Necrosis Factor (TNF) and Mitogen-Activated Protein Kinase (MAPK) signaling pathways while inhibiting the Vascular Endothelial Growth Factor (VEGF) signaling pathway, ultimately leading to NOA. Through the integration of machine learning techniques, 5 hub genes (AUC > 0.7) induced by TCDD and associated with NOA were identified: Androgen receptor (AR), Chromodomain Helicase DNA-Binding Protein 1 (CHD1), Discoidin Domain Receptor Tyrosine Kinase 2 (DDR2), Retinoic Acid Receptor-Related Orphan Receptor Alpha (RORA), and Glutamate Ionotropic Receptor AMPA Type Subunit 1 (GRIA1). WGCNA and single-cell analysis revealed that AR and DDR2 were specifically expressed in the testicular tissues of NOA patients and were closely associated with SCOS (p < 0.05). Immune infiltration analysis suggested that TCDD induces abnormal infiltration of various immune cells, indicating its close relationship with immune inflammatory responses (p < 0.05). Biomolecular modeling further demonstrated a strong binding affinity between AR and TCDD (∆G = -8.3 kcal·mol⁻¹, Etotal = -37.79 kcal·mol⁻¹), highlighting the critical role of AR in TCDD-induced NOA.

CONCLUSIONS

This study reveals the potential molecular mechanisms by which TCDD induces NOA, providing new targets for the development of diagnostic and therapeutic strategies.

In Vitro Exposure to the Endocrine-Disrupting Chemical Climbazole Impairs Human Sperm Motility, Hormonal Signalling, and Mitochondrial Activity

This study explores the endocrine-disrupting effects of climbazole (CBZ), an environmental and lifestyle stressor, on male fertility. The impact of CBZ on sperm vitality, motility, and molecular pathways related to hormone receptors and apoptosis was evaluated, in non-capacitated and capacitated conditions. Gene expression of key components, including hormone receptors (ESR1, ESR2, FSHR, AR), apoptosis-related genes (BAX, BCL2), and COX4l1 (involved in mitochondrial function), was analyzed. Protein tyrosine phosphorylation, a marker of capacitation, was also examined using immunofluorescence and Western blot analysis. We demonstrated that CBZ significantly reduced sperm vitality at concentrations above 25 µM and motility at 1 and 10 µM in non-capacitated and capacitated conditions. Changes in tyrosine phosphorylation patterns were also observed. Gene expression analysis revealed an upregulation of ESR1, ESR2, FSHR, and BAX, while AR and COX4l1 expression were downregulated. These findings offer new insights into the potential endocrine-disrupting and cytotoxic effects of CBZ, highlighting its potential role in compromising male reproductive health.

Clinical and Laboratorial Evaluation of Male Infertility. A Detailed Practical Approach

Infertility, defined as the inability to achieve pregnancy after one year of unprotected, frequent sexual intercourse, is a global burden that affects approximately 15% of couples, or 190-230 million people worldwide, who are trying to start a family. The male contributes significantly, directly accounting for 30-35% and up to 52% of total couple infertility, affecting approximately 7-8% of all men. This work aims to present, in a didactic and objective way, a standardization of the initial steps toward a thorough evaluation of subfertile and infertile men. We have focused on the evaluation of initial management, emphasizing the need for a comprehensive evaluation that includes a detailed history, physical examination, and semen analysis as the golden triple helix of basic evaluation of the infertile male. General and genital physical examinations are highly valuable due to the wealth of information they provide, from potential diagnoses to pregnancy prognoses. Comprehensive and quality-controlled semen analysis provides reliable information as a baseline test to evaluate the patency of the reproductive tract and to evaluate basic sperm parameters and fertility potential. However, it is not a fertility determinant and should preferentially be complemented with sperm functional tests. like biomarkers of oxidative stress, sperm immaturity and DNA fragmentation. Most cases of infertility require evaluation by a specialist in andrology, nonetheless the understanding and rationale of the initial assessment of the infertile male can be undertaken by non-specialists, thus improving the care and counseling of couples facing this troubling issue and avoiding unnecessary use of assisted reproductive technologies (ART) since most cases of male infertility can be treated and reversed by medical or surgical interventions, and the fertility status can be restored. The ultimate goal is to achieve natural pregnancy, the use of ART should not be the initial offered resource.

Effects of SpGSH1 and SpPCS1 overexpression or co-overexpression on cadmium accumulation in yeast and Spirodela polyrhiza

Cadmium (Cd) is one of the most toxic elements to all organisms. Glutathione (GSH)-dependent phytochelatin (PC) synthesis pathway is considered an extremely important mechanism in Cd detoxification in plants. However, few studies have focused on the roles of glutamate-cysteine ligase (GSH1) and phytochelatin synthase (PCS1) in Cd accumulation and detoxification in plants. In this study, SpGSH1 and SpPCS1 were identified and cloned from Spirodela polyrhiza and analyzed their functions in yeast and S. polyrhiza via single- or dual-gene (SpGP1) overexpression. The findings of this study showed that SpGSH1, SpPCS1, and SpGP1 could dramatically rescue the growth of the yeast mutant Δycf1. In S. polyrhiza, SpGSH1 was located in the cytoplasm and could promote Mn and Ca accumulation. SpPCS1 was located in the cytoplasm and nucleus, mainly expressed in meristem regions, and promoted Cd, Fe, Mn, and Ca accumulation. SpGSH1 and SpPCS1 co-overexpression increased the Cd, Mn, and Ca contents. Based on the growth data of S. polyrhiza, it was recommended that biomass as the preferable indicator for assessing plant tolerance to Cd stress compared to frond number in duckweeds. Collectively, this study for the first time systematically elaborated the function of SpGSH1 and SpPCS1 for Cd detoxification in S. polyrhiza.

Antioxidants in mitigating phthalate-induced male reproductive toxicity: A comprehensive review

Phthalates, widely used as plasticizers, have been increasingly linked to male reproductive toxicity through mechanisms including oxidative stress, endocrine disruption, inflammation, and apoptosis. This comprehensive review evaluates the protective role of various antioxidants in mitigating the detrimental effects of phthalates such as di-(2-ethylhexyl) phthalate (DEHP), di-butyl phthalate (DBP), mono-(2-ethylhexyl) phthalate (MEHP), and monobutyl phthalate (MBP) on male reproductive health. Antioxidants such as lycopene, ellagic acid, genistein, and selenium compounds exhibit significant efficacy in counteracting phthalate-induced damage by neutralizing reactive oxygen species (ROS), enhancing endogenous antioxidant defenses, reducing inflammatory responses, and preventing apoptosis. Lycopene demonstrates broad-spectrum protective effects, particularly through its high ROS-scavenging capacity and ability to preserve mitochondrial function. Ellagic acid effectively ameliorates oxidative stress and inflammation, while genistein enhances the Nrf2 pathway and restores hormonal balance, offering robust protection against reproductive toxicity. Selenium compounds improve antioxidant enzyme activities, providing essential support against oxidative damage. These findings underscore the potential of antioxidants as therapeutic agents against phthalate-induced male reproductive dysfunction. Future research should focus on optimizing antioxidant combinations, understanding dose-response relationships, and assessing long-term efficacy and safety to develop effective interventions for safeguarding male reproductive health.

Cytoprotective potency of naringin against di-n-butylphthalate (DBP)-induced oxidative testicular damage in male rats

The present study aimed to investigate the protective potential of naringin (NG) against di-n-butyl phthalate (DBP)- induced testicular damage and impairment of spermatogenesis in rats. Forty-two male Wistar albino rats were divided into six equal groups, and treated orally, 3 times weekly for 8 successive weeks. Control vehicle group was administrated olive oil, naringin-treated group was administered NG (80 mg/kg), DBP 250- and DBP 500- intoxicated groups received DBP (250 mg/kg) and (500 mg/kg), respectively, NG + DBP 250 and NG + DBP 500 groups received NG, an hour prior to DBP 250 and 500 administration. The results revealed that DBP induced dose-dependent male reproductive dysfunctions, included a significant decrease in the serum testosterone level concomitantly with significant decreases in the sperm count, viability, and total motility. Meanwhile, DBP significantly increased the testicular malondialdehyde level with significant reductions of glutathione content and catalase activity. Histopathologically, DBP provoked absence of spermatozoa, degenerative changes in the cell layers of seminiferous tubules and a significant decrease in the thickness of the seminiferous tubules epithelium. Conversely, the concomitant treatment with NG, one hour before DBP 250 or 500- intoxication mitigated the dose-dependent reproductive dysfunctions induced by DBP, evidenced by significant increases of serum testosterone level, sperm motility, count and viability along with marked improvement of the oxidant/antioxidant status and testicular histoarchitecture. In conclusion, the findings recorded herein proved that NG could mitigate DBP-induced testicular damage and impairment of spermatogenesis, suggesting the perspective of using NG as a natural protective and therapeutic agent for alleviating the reproductive dysfunctions and improving reproductive performance, mainly via its potent antioxidant activity.

Combined effect of polystyrene nanoplastic and di-n-butyl phthalate on testicular health of male Swiss albino mice: analysis of sperm-related parameters and potential toxic effects

Plastics, especially polystyrene nanoplastic particles (PSNPs), are known for their durability and absorption properties, allowing them to interact with environmental pollutants such as di-n-butyl phthalate (DBP). Previous research has highlighted the potential of these particles as carriers for various pollutants, emphasizing the need to understand their environmental impact comprehensively. This study focuses on the subchronic exposure of male Swiss albino mice to PSNP and DBP, aiming to investigate their reproductive toxicity between these pollutants in mammalian models. The primary objective of this study is to examine the reproductive toxicity resulting from simultaneous exposure to PSNP and DBP in male Swiss albino mice. The study aims to analyze sperm parameters, measure antioxidant enzyme activity, and conduct histopathological and morphometric examinations of the testis. By investigating the individual and combined effects of PSNP and DBP, the study seeks to gain insights into their impact on the reproductive profile of male mice, emphasizing potential synergistic interactions between these environmental pollutants. Male Swiss albino mice were subjected to subchronic exposure (60 days) of PSNP (0.2 mg/m, 50 nm size) and DBP (900 mg/kg bw), both individually and in combination. Various parameters, including sperm parameters, antioxidant enzyme activity, histopathological changes, and morphometric characteristics of the testis, were evaluated. The Johnsen scoring system and histomorphometric parameters were employed for a comprehensive assessment of spermatogenesis and testicular structure. The study revealed non-lethal effects within the tested doses of PSNP and DBP alone and in combination, showing reductions in body weight gain and testis weight compared to the control. Individual exposures and the combination group exhibited adverse effects on sperm parameters, with the combination exposure demonstrating more severe outcomes. Structural abnormalities, including vascular congestion, Leydig cell hyperplasia, and the extensive congestion in tunica albuginea along with both ST and Leydig cell damage, were observed in the testis, underscoring the reproductive toxicity potential of PSNP and DBP. The Johnsen scoring system and histomorphometric parameters confirmed these findings, providing interconnected results aligning with observed structural abnormalities. The study concludes that simultaneous exposure to PSNP and DBP induces reproductive toxicity in male Swiss albino mice. The combination of these environmental pollutants leads to more severe disruptions in sperm parameters, testicular structure, and antioxidant defense mechanisms compared to individual exposures. The findings emphasize the importance of understanding the interactive mechanisms between different environmental pollutants and their collective impact on male reproductive health. The use of the Johnsen scoring system and histomorphometric parameters provides a comprehensive evaluation of spermatogenesis and testicular structure, contributing valuable insights to the field of environmental toxicology.

Oyster Peptide-Zinc Complex Ameliorates Di-(2-ethylhexyl) Phthalate-Induced Testis Injury in Male Mice and Improving Gut Microbiota

Di-(2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer, which can cause damage to male reproductive organs, especially the atrophy of the testis. Meanwhile, DEHP can also lead to a decrease in testicular zinc content, but the role of zinc remains unclear. This study aims to prepare oyster peptide-zinc complex (OPZC) to alleviate DEHP-induced reproductive damage in mice. OPZC was successfully obtained through electron microscopy, X-ray diffraction, and thermogravimetric analysis, with stable structure and high water-solubility. Low dose oyster peptide-zinc complex (OPZCL) significantly reduced the reproductive damage caused by DEHP in mice. Further research had shown that OPZCL restored the content of serum hormones and the activity of oxidative stress kinases to normal, while also normalizing testicular zinc and selenium levels. In addition, it also recovered the disorder of gut microbiota, reduced the proportion of Bacteroides, increased the abundance of Ligilactobacillus, and restored the proportion of Acidobacteriota, Chloroflexi, and Proteobacteria. Therefore, OPZCL can relieve the reproductive damage caused by DEHP in mice by restoring testicular zinc homeostasis and the composition of intestinal microbiota, indicating that OPZCL has a potential protective effect on male reproductive health.

Exploring the Occurrence of Organic Contaminants in Human Semen through an Innovative LC-HRMS-Based Methodology Suitable for Target and Nontarget Analysis

Understanding the potential impact of organic contaminants on male fertility is crucial, yet limited studies have examined these chemicals in semen, with most focusing on urine and blood. To address this gap, we developed and validated a robust LC-HRMS methodology for semen analysis, with a focus on polar and semipolar chemicals. Our methodology enables the quantitative (or semiquantitative) analysis of >2000 chemicals being compatible with suspect and nontarget strategies and providing unprecedented insights into the occurrence and potential bioaccumulation of diverse contaminants in this matrix. We comprehensively analyzed exogenous organic chemicals and associated metabolites in ten semen samples from Spanish participants collected in an area with a large presence of the chemical industry included in the LED-FERTYL Spanish study cohort. This investigation revealed the presence of various contaminants in semen, including plastic additives, PFAS, flame retardants, surfactants, and insecticides. Notably, prevalent plastic additives such as phthalic acid esters and bisphenols were identified, indicating potential health risks. Additionally, we uncovered previously understudied chemicals like the tire additive 2-mercaptobenzothiazole and specific organophosphate flame retardants. This study showcases the potential of our methodology as a valuable tool for large-scale cohort studies, providing insights into the association between contaminant exposure and the risk of male fertility impairments.

Environmental and occupational exposure to cadmium associated with male reproductive health risk: a systematic review and meta-analysis based on epidemiological evidence

There is an abundance of epidemiological evidence and animal experiments concerning the correlation between cadmium exposure and adverse male reproductive health outcomes. However, the evidence remains inconclusive. We conducted a literature search from PubMed, Embase, and Web of Science over the past 3 decades. Pooled r and 95% confidence intervals (CIs) were derived from Cd levels of the type of biological materials and different outcome indicators to address the large heterogeneity of existing literature. Cd was negatively correlated with semen parameters (r = - 0.122, 95% CI - 0.151 to - 0.092) and positively correlated with sera sex hormones (r = 0.104, 95% CI 0.060 to 0.147). Among them, Cd in three different biological materials (blood, semen, and urine) was negatively correlated with semen parameters, while among sex hormones, only blood and urine were statistically positively correlated. In subgroup analysis, blood Cd was negatively correlated with semen density, sperm motility, sperm morphology, and sperm count. Semen Cd was negatively correlated with semen concentration. As for serum sex hormones, blood Cd had no statistical significance with three hormones, while semen Cd was negatively correlated with testosterone. In summary, cadmium exposure might be associated with the risk of a decline in sperm quality and abnormal levels of sex hormones.

LncRNA5251 inhibits spermatogenesis via modification of cell-cell junctions

BACKGROUND

Male factors-caused decline in total fertility has raised significant concern worldwide. LncRNAs have been identified to play various roles in biological systems, including spermatogenesis. This study aimed to explore the role of lncRNA5251 in mouse spermatogenesis.

METHODS

The expression of lncRNA5251 was modulated in mouse testes in vivo or spermatogonial stem cells (C18-4 cells) in vitro by shRNA.

RESULTS

The sperm motility in two generations mice after modulation of lncRNA5251 (muF0 and muF1) was decreased significantly after overexpression of lncRNA5251. GO enrichment analysis found that knockdown lncRNA5251 increased the expression of genes related to cell junctions, and genes important for spermatogenesis in mouse testes. Meanwhile, overexpressing lncRNA5251 decreased the gene and/or protein expression of important genes for spermatogenesis and immune pathways in mouse testes. In vitro, knockdown lncRNA5251 increased the expression of genes for cell junction, and the protein levels of some cell junction proteins such as CX37, OCLN, JAM1, VCAM1 and CADM2 in C18-4 cells. LncRNA5251 is involved in spermatogenesis by modulation of cell junctions.

CONCLUSION

This will provide a theoretical basis for improving male reproductive ability via lncRNA.

High-content analysis of testicular toxicity of BPA and its selected analogs in mouse spermatogonial, Sertoli cells, and Leydig cells revealed BPAF induced unique multinucleation phenotype associated with the increased DNA synthesis

Bisphenol A is an endocrine disruptor that has been shown to have testicular toxicity in animal models. Its structural analog, including bisphenol S (BPS), bisphenol AF (BPAF), and tetrabromobisphenol A (TBBPA) have been introduced to the market as BPA alternatives. Previously, we developed high-content analysis (HCA) assays and applied machine learning to compare the testicular toxicity of BPA and its analogs in spermatogonial cells and testicular cell co-culture models. There are diverse cell populations in the testis to support spermatogenesis, but their cell type-specific toxicities are still not clear. The purpose of this study is to examine the selective toxicity of BPA, BPS), BPAF, and TBBPA on these testicular cells, including Sertoli cells, Leydig cells, and spermatogonia cells. We developed a high-content image-based single-cell analysis and measured a broad spectrum of adverse endpoints related to the development of reproductive toxicology, including cell number, nuclear morphology, DNA synthesis, cell cycle progression, early DNA damage response, cytoskeleton structure, DNA methylation status, and autophagy. We introduced an HCA index and spectrum to reveal multiple HCA parameters and observed distinct toxicity profiling of BPA and its analogs among three testicular types. The HCA spectrum shows the dynamic, chemical-specific, dose-dependent changes of each HCA parameter. Each chemical displayed a unique dose-dependent profile within each type of cell. All three types of cells showed the highest response to BPAF at 10 μM across all endpoints measured. BPAF targeted spermatogonial cell (C18) more significantly at 5 μM. BPS more likely targeted Sertoli cell (TM4) and Leydig cell (TM3) and less at spermatogonia cells. TBBPA targeted spermatogonia, Sertoli cells, and less at TM3 cells. BPA is mainly targeted at TM4, followed by TM3 cells, and less at spermatogonial cells. Most importantly, we observed that BPAF induced a dose-dependent increase in spermatogonia cells, not in Sertoli and Leydig cells. In summary, our current HCA assays revealed the cell-type-specific toxicities of BPA and its analogs in different testicular cells. Multinucleation induced by BPAF, along with increased DNA damage and synthesis at low doses, could possibly have a profound long-term effect on reproductive systems.

Oxidative Stress, Cytotoxic and Inflammatory Effects of Azoles Combinatorial Mixtures in Sertoli TM4 Cells

Triazole and imidazole fungicides are an emerging class of contaminants with an increasing and ubiquitous presence in the environment. In mammals, their reproductive toxicity has been reported. Concerning male reproduction, a combinatorial activity of tebuconazole (TEB; triazole fungicide) and econazole (ECO; imidazole compound) in inducing mitochondrial impairment, energy depletion, cell cycle arrest, and the sequential activation of autophagy and apoptosis in Sertoli TM4 cells (SCs) has recently been demonstrated. Given the strict relationship between mitochondrial activity and reactive oxygen species (ROS), and the causative role of oxidative stress (OS) in male reproductive dysfunction, the individual and combined potential of TEB and ECO in inducing redox status alterations and OS was investigated. Furthermore, considering the impact of cyclooxygenase (COX)-2 and tumor necrosis factor-alpha (TNF-α) in modulating male fertility, protein expression levels were assessed. In the present study, we demonstrate that azoles-induced cytotoxicity is associated with a significant increase in ROS production, a drastic reduction in superoxide dismutase (SOD) and GSH-S-transferase activity levels, and a marked increase in the levels of oxidized (GSSG) glutathione. Exposure to azoles also induced COX-2 expression and increased TNF-α production. Furthermore, pre-treatment with N-acetylcysteine (NAC) mitigates ROS accumulation, attenuates COX-2 expression and TNF-α production, and rescues SCs from azole-induced apoptosis, suggesting a ROS-dependent molecular mechanism underlying the azole-induced cytotoxicity.

Changes in testicular histomorphometry and ultrastructure of Leydig cells in adult male Japanese quail exposed to di (n-butyl) phthalate (DBP) during the prepubertal period

Phthalate esters, such as di(n-butyl) phthalate, (DBP), are synthetic chemical pollutants commonly used as plasticizers in the manufacture of plastics. In the present study, we investigated the effects of DBP in the testes of adult male quails (Coturnix cortunix japonica) exposed by oral gavage to variable doses of DBP (0 [control], 1, 10, 50, 200, and 400 mg/kgbw^-d), for 30 days during the prepubertal period, using histo-morphometric and ultrastructural techniques. Generally, significant decreases in seminiferous tubular diameter (STD) and epithelial height (SEH) were observed predominantly at the highest DBP doses (200 and 400 mg/kg), as compared to medium (50 mg/kg), and lowest doses (1 and 10 mg/kg) as well as the control group. Ultrastructurally, apparent dose-specific degenerative changes were observed in the Leydig cells. The lowest DBP doses (1 and 10 mg/kg) did not produce significant effects on Leydig cell ultrastructure, whereas, at the highest doses (200 and 400 mg/kg), the Leydig cells were remarkably conspicuous in the interstitium and appeared foamy. There was a preponderance of electron-lucent lipid droplets which crowded out the normal organelles of the cell, as well as increases in the number of dense bodies in the cytoplasm. The smooth endoplasmic reticulum (sER) was less obvious, compacted, and wedged between the abundant lipid droplets and mitochondria. Taken together, these findings indicate that pre-pubertal exposure of precocious quail birds to DBP, produced parameter-specific histometric tubular changes, as well as dose-dependent cyto-structural derangement of the Leydig cells; which consequently may lead to overt reproductive impairments in the adult bird in the environment.

Urinary concentrations of organophosphate esters in relation to semen quality: A cross-sectional study

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers in consumer products. Toxicological studies have indicated that OPEs may affect male reproductive health, but human evidence is inconclusive. In this study, we explored associations of individual and mixtures of OPE exposure with semen quality among 1015 Chinese men from an infertility clinic. After adjusting for potential confounders, we observed that higher diphenyl phosphate (DPHP) and [Bis(2-methylphenyl) phosphate (BMPP)] exposure was associated with increased odds ratios (ORs) of having below-reference total sperm count. Higher bis (2-butoxyethyl) phosphate (BBOEP) exposure was associated with increased ORs of having below-reference progressive motility and total motility. For semen quality parameters modeled as continuous outcomes, inverse associations with individual OPE were still observed. In addition, urinary 1-hydroxy-2-propyl bis (1-chloro-2-propyl) phosphate (BCIPHIPP) concentrations were inversely associated with the percentage of normal morphology while positively associated with the percentage of abnormal heads. Quantile g-computation regression analyses showed that exposure to higher OPE mixtures was associated with lower total sperm motility and normal morphology. Our results indicated that both individual and mixtures of OPE exposure were associated with reduced semen quality.

The comparison of Y chromosome microdeletion incidence in blood DNA and sperm cell DNA

BACKGROUND

During gamete development and spermatogenesis, certain genes on the Y chromosome (Yq) in the Male-Specific Region (MSR) are responsible for human gametes formation. The long arm Yq is composed of both euchromatin and the genetically inactive heterochromatin regions. This region contains the Azoospermia factors AZFa, AZFb and AZFc. In the case of male infertility, microdeletions on the Yq chromosome appear to be structural chromosomal anomalies linked to sperm abnormality.

METHODS

The present study aimed to look at the incidence, of Asthenospermia (AS), Teratospermia (TS), Oligospermia (OS) and Oligoasthenoteratospermia (OAT) patterns of Y chromosomal microdeletions in Indian infertile men with an (AZF a, b, c). This study was conducted with 75 infertile men as cases and 75 fertile men as a control for AZF locus microdeletion utilizing sequence-tagged sites.

RESULTS

The AZFc region of germ cell DNA (50.6%) was the most deleted section in infertile men when compared to blood DNA (21.3%), followed by deletions in the AZFb region (21.3%) in germ cell DNA whereas blood DNA had no microdeletion in the AZFa region in both germ cell DNA and blood DNA. Infertile men displayed significant Yq microdeletion in both AZFb and also AZFc. Around 33% (25) of 75 infertile men had AZF (a, b, c) region microdeletion in blood DNA, compared to it germ cell DNA had a larger percentage of 72% (54) of Y chromosome microdeletions in the study samples.

CONCLUSION

A high-frequency rate of microdeletions seen in germ cell DNA. PCR-based Y chromosome microdeletion screening using germ cell DNA along with Genomic DNA might help in screening for genetic abnormality in infertile men who endure assisted reproductive technology treatments. This study might be attributable to the interplay of lifestyle and genetic factors, both contributing to the risk of developing these germ-line deletions.

Reproductive toxicity of maternal exposure to di(2-ethylhexyl)phthalate and butyl paraben (alone or in association) on both male and female Wistar offspring

Parabens and phthalates are commonly found as contaminants in human fluids and are able to provoke reproductive toxicity, being considered endocrine disruptors. To evaluate the effects of phthalate and paraben, alone or in combination, on reproductive development of the offspring, female pregnant Wistar rats were allocated in six experimental groups: Three control groups (gavage [CG], subcutaneous [CS], and gavage + subcutaneous) received corn oil as vehicle, and the remaining groups were exposed to di(2-ethylhexyl)phthalate (DEHP) (500 mg/kg, gavage), butyl paraben (BP) (100 mg/kg, subcutaneously), or MIX (DEHP + BP), from Gestational Day 12 until Postnatal Day (PND) 21. The following parameters were assessed on the offspring: anogenital distance and weight at PND 1, nipple counting at PND 13, puberty onset, estrous cycle, weights of reproductive and detoxifying organs, histological evaluation of reproductive organs, and sperm evaluations (counts, morphology, and motility). Female pups from MIX group presented reduced body weight at PND 1, lower AGD, and decreased endometrium thickness. Male animals showed decreased body weight at PND 1 and lower number of Sertoli cells on DEHP and MIX groups, MIX group revealed increase of abnormal seminiferous tubules, DEHP animals presented delayed preputial separation and higher percentage of immotile sperms, and BP males presented diminished number of Leydig cells. In conclusion, the male offspring was more susceptible to DEHP toxicity; even when mixed to paraben, the main negative effects observed seem to be due to antiandrogenic phthalate action. On the other hand, DEHP seems to be necessary to improve the effects of BP on reducing estrogen-dependent and increasing androgen-dependent events.

Male reproductive toxicity of polystyrene microplastics: Study on the endoplasmic reticulum stress signaling pathway

Microplastics (MPs) have raised health concerns in public for its potential reproductive toxicity. In this study, we subjected the Kunming mice to 0.01, 0.1 and 1.0 mg/day polystyrene MPs (10 μm, PS-MPs) for 35 days, aiming to investigate the relevant male reproductive toxicity and latent molecular mechanism. The results showed the decreased sperm counts and motility, while the elevated sperm abnormality in PS-MPs-exposed mice. Testicular H&E staining displayed the vacuolization, atrophy, and even shedding of germ cells in seminiferous tubule. And the testosterone content in serum also decreased with PS-MPs treatment. Moreover, molecular analysis indicated that PS-MPs upregulated the expression trait factors for ERS (e.g., immunoglobulin-binding protein [BIP], inositol-requiring protein 1α [IRE1α], X-box-binding protein 1 splicing [XBP1s], Jun kinase [JNK], and the transcription of CCAAT/enhancer-binding protein (C/EBP) homologous protein [CHOP]) and downstream apoptotic modulator (e.g., Caspase-12, -9, and -3) in the testis. The steroidogenic acute regulatory protein (StAR), the testosterone synthetic initiator, was also downregulated. With the supplementation of ERS inhibitor, the MPs-induced testicular damage and decreased testosterone were improved to almost normal level. Overall, this study suggested that PS-MPs generate reproductive toxicity possibly via activating ERS and apoptosis signaling pathway.

Impact of Fetal Exposure to Endocrine Disrupting Chemical Mixtures on FOXA3 Gene and Protein Expression in Adult Rat Testes

Perinatal exposure to endocrine disrupting chemicals (EDCs) has been shown to affect male reproductive functions. However, the effects on male reproduction of exposure to EDC mixtures at doses relevant to humans have not been fully characterized. In previous studies, we found that in utero exposure to mixtures of the plasticizer di(2-ethylhexyl) phthalate (DEHP) and the soy-based phytoestrogen genistein (Gen) induced abnormal testis development in rats. In the present study, we investigated the molecular basis of these effects in adult testes from the offspring of pregnant SD rats gavaged with corn oil or Gen + DEHP mixtures at 0.1 or 10 mg/kg/day. Testicular transcriptomes were determined by microarray and RNA-seq analyses. A protein analysis was performed on paraffin and frozen testis sections, mainly by immunofluorescence. The transcription factor forkhead box protein 3 (FOXA3), a key regulator of Leydig cell function, was identified as the most significantly downregulated gene in testes from rats exposed in utero to Gen + DEHP mixtures. FOXA3 protein levels were decreased in testicular interstitium at a dose previously found to reduce testosterone levels, suggesting a primary effect of fetal exposure to Gen + DEHP on adult Leydig cells, rather than on spermatids and Sertoli cells, also expressing FOXA3. Thus, FOXA3 downregulation in adult testes following fetal exposure to Gen + DEHP may contribute to adverse male reproductive outcomes.

Intergenerational toxic effects of parental exposure to bisphenol AF on offspring and epigenetic modulations in zebrafish

Bisphenol AF (BPAF), an endocrine-disrupting chemical, has been detected in various environmental media because of its wide industrial applications. Meanwhile, substances that are known to be toxic to the reproductive system have been observed to interfere with the development of the offspring following parental exposure. This study was aimed at determining the gender-dependent intergenerational effects of BPAF on offspring development following either paternal or maternal exposure of adult zebrafish to an environmental concentration of BPAF. Four-month-old zebrafish (F0) were exposed to 10 μg/L of BPAF for 28 days, the developmental endpoints of F1 embryos were then tested without further treatment with BPAF. The results show that paternal BPAF exposure decreased the hatching rate, increased mortality, and shortened the body lengths of F1 larval offspring. In addition, it changed DNA and m⁶A RNA methylation gene expression levels in F0 testes and F1 larvae. Although maternal exposure increased mortality and enhanced antioxidant enzyme activities in F1 larvae, only DNA methylation gene expression was altered in F0 ovaries and F1 larvae. In addition, a short term BPAF exposure of zebrafish embryos from 4 h post-fertilization (hpf) until 120 hpf similarly impaired the early development of the larvae but only at a level relatively higher than 10 μg/L; and DNA and RNA methylation gene expression was regulated to some extent in BPAF exposure groups. Overall, our results indicate the gender-specific effects of BPAF on offspring development and epigenetic modulations, suggesting a relatively high susceptibility within the exposure window during gametogenesis and early embryonic developmental stages to environmental chemicals.

Synergistic Activity of Ketoconazole and Miconazole with Prochloraz in Inducing Oxidative Stress, GSH Depletion, Mitochondrial Dysfunction, and Apoptosis in Mouse Sertoli TM4 Cells

Triazole and imidazole fungicides represent an emerging class of pollutants with endocrine-disrupting properties. Concerning mammalian reproduction, a possible causative role of antifungal compounds in inducing toxicity has been reported, although currently, there is little evidence about potential cooperative toxic effects. Toxicant-induced oxidative stress (OS) may be an important mechanism potentially involved in male reproductive dysfunction. Thus, to clarify the molecular mechanism underlying the effects of azoles on male reproduction, the individual and combined potential of fluconazole (FCZ), prochloraz (PCZ), miconazole (MCZ), and ketoconazole (KCZ) in triggering in vitro toxicity, redox status alterations, and OS in mouse TM4 Sertoli cells (SCs) was investigated. In the present study, we demonstrate that KCZ and MCZ, alone or in synergistic combination with PCZ, strongly impair SC functions, and this event is, at least in part, ascribed to OS. In particular, azoles-induced cytotoxicity is associated with growth inhibitory effects, G0/G1 cell cycle arrest, mitochondrial dysfunction, reactive oxygen species (ROS) generation, imbalance of the superoxide dismutase (SOD) specific activity, glutathione (GSH) depletion, and apoptosis. N-acetylcysteine (NAC) inhibits ROS accumulation and rescues SCs from azole-induced apoptosis. PCZ alone exhibits only cytostatic and pro-oxidant properties, while FCZ, either individually or in combination, shows no cytotoxic effects up to 320 µM.

Parental exposure to 3-methylcholanthrene before gestation adversely affected the endocrine system and spermatogenesis in male F1 offspring

The compound 3-methylcholanthrene (3-MC) is an environmental pollutant belonging to the PAHs, which reportedly have the potential to disrupt the endocrine systems of animals. In the present study, 4-week-old male and female mice were given 3-MC through their diet at a dose of 0.5mg/kg of chow for 6 weeks before pregnancy. The first filial (F₁) generation offspring of exposed or unexposed parental mice were sacrificed at the age of 5 or 10 weeks (F₁-5W or F₁-10W), and the potential effects on the F₀ and F₁ offspring were evaluated. The results showed that the serum and testicular testosterone (T) levels and the genes involved in T synthesis in F₀ males and male F₁-5W individuals born from female mice exposed to 3-MC were significantly decreased. In addition, histological analysis suggested that exposure to 3-MC significantly disrupted testicular morphology in F₀ mice and in the offspring of female mice exposed to 3-MC. Further investigation revealed that genes involved in spermatogenesis, such as Phosphoglycerate kinase 2 (Pgk2), Glial cell derived neurotrophic factor (Gdnf), Myeloblastosis oncogene (Myb), DEAD box helicase 4 (Ddx4) and KIT proto-oncogene receptor tyrosine kinase (Kit), were suppressed in these mice. However, the adverse effects of parental 3-MC exposure on the adolescent mice were mitigated when they grew to adulthood, which was verified by studies on F₁-10W mice. Our results suggest that female exposure to 3-MC has the potential to disrupt the endocrine system and spermatogenesis in male offspring; nevertheless, the adverse effects might be mitigated with age.

ICSI outcomes for infertile men with severe or complete asthenozoospermia

BACKGROUND

Severe or complete asthenozoospermia is a rare entity that can lead to male infertility. In this study, we explored whether different extents of severe or complete asthenozoospermia could affect intracytoplasmic sperm injection (ICSI) outcomes and compared the ICSI outcomes using testicular spermatozoa with those using ejaculated spermatozoa in couples with complete asthenozoospermia.

RESULTS

Ninety-seven couples with severe or complete asthenozoospermia who underwent ICSI between January 2014 and December 2018 were included. According to the sperm category used in ICSI, patients were categorized into four groups: ejaculated progressive motile sperm group (Ep-group), ejaculated non-progressive motile sperm group (En-group), ejaculated immotile sperm group (Ei-group), and testicular sperm group (TESE-group). We compared the baseline characteristics, hormone profile, semen parameters, normal fertilization, good-quality embryos on day 3, transferred embryos, and ICSI outcomes in the four groups. The clinical pregnancy rate was significantly increased in the Ep-group (65.4%, P = 0.019) and TESE-group (63.6%, P = 0.035) compared with that in the Ei-group (23.1%). The ongoing pregnancy rate in the Ei-group was significantly lower than that in the Ep-group (23.1% vs. 61.5%, P = 0.041). Moreover, the biochemical pregnancy rate, ongoing pregnancy rate, and live birth rate were much lower in the Ei-group than in the TESE-group (30.8% vs. 63.6%, 23.1% vs. 40.4% and 23.1% vs. 40.4%, respectively).

CONCLUSIONS

In couples with complete asthenozoospermia, testicular spermatozoa should be preferred to ejaculated spermatozoa for obtaining a better ICSI outcome. With the appropriate selection of testicular spermatozoa, the extent of severe or complete asthenozoospermia may not affect the ICSI outcomes. Future studies with a larger sample size are warranted to validate these findings.

Association between ambient particulate matter exposure and semen quality in fertile men

BACKGROUND

Several studies have suggested adverse effects of particulate matter (PM) exposure on male reproductive health; few have investigated the association between PM exposure and semen quality in a large population of fertile men.

METHODS

We evaluated 14 parameters of semen quality in 1554 fertile men in Nanjing from 2014 to 2016. Individual exposure to particular matter ≤10 μm in diameter (PM10) and ≤ 2.5 μm in diameter (PM2.5) during key periods of sperm development (0-90, 0-9, 10-14, 15-69, and 70-90 days before semen collection) were estimated by inverse distance weighting interpolation. Associations between PM exposure and semen quality were estimated using multivariable linear regression.

RESULTS

Higher 90-days average PM2.5 was in association with decreased sperm motility (2.21% for total motility, 1.93% for progressive motility per 10 μg/m3 increase, P <  0.001) and four quantitative aspects of sperm motion (curvilinear velocity (VCL), straight line velocity (VSL), average path velocity (VAP), and amplitude of lateral head displacement (ALH), P <  0.01). The association between PM2.5 exposure and semen quality were generally stronger for the earlier exposure window (70-90 days prior to ejaculation) than for recent exposure (0-9, 10-14, or 15-69 days). In the subgroup of men who had normal sperm parameters (n = 1019), similar results were obtained. Ninety-days PM10 exposure was associated only with decreased VCL and VAP and was not related to sperm concentration.

CONCLUSIONS

Exposure to PM2.5 adversely affects semen quality, specifically lower sperm motility, in fertile men.

Enhanced remediation of pollutants by microorganisms-plant combination

The pollutants have become ubiquitous in the total environment (water, soil and air) due to human activities and they are hazardous to all forms of life on the earth. This problem has made scientists focus on mitigating or complete reduction in pollutants by several means. Microorganism and plants are known to scavenge pollutants. Both are studied enormously in reducing, refining, and removing pollutants from the environment successfully. But, their slow process for removal is disadvantage. However, according to recent advancements in the abatement of pollutants, a combined system of both microorganisms and plant has shown to enhance the remediation of pollutants to an efficient level. In a nutrient-depleted pollutant-rich environment, when suitable plant and microorganisms are introduced, the plant interacts with the rhizosphere and root associate with microorganisms to survive in toxic conditions. The chemicals released by plants signal the microorganisms for interactions. This interaction leads in higher germination efficiency and enhanced root elongation which results in enhanced degradation of pollutants in both rhizosphere and phyllosphere. In this background, the current review article provides an overview of the recent advancement in microorganisms plant combined systems in enhanced removal of several recalcitrant pollutants. The conclusion highlights the challenges and future perspectives in this area of research.

Lycopene prevents DEHP-induced testicular endoplasmic reticulum stress via regulating nuclear xenobiotic receptors and unfolded protein response in mice

Lycopene (LYC) is a potent antioxidant synthesized by red vegetables or plants. Di-2-ethylhexyl phthalate (DEHP) is frequently detected in diverse agricultural environments and considered as a reproductive toxicant. The present research was designed to assess the potential mechanisms of DEHP-induced testicular toxicity and the treatment efficacy of LYC. In this study, after the oral administration of LYC at the dose of 5 mg per kg b.w. per day, mice were given 500 or 1000 mg per kg b.w. per day of DEHP. This research suggested that LYC prevented the DEHP-induced disorder at the levels of activity and content of CYP450 enzymes. LYC attenuated DEHP-caused enhancement in nuclear xenobiotic receptors (NXRs) and the phase I metabolizing enzymes (CYP1, CYP2, CYP3, etc.) levels. Furthermore, endoplasmic reticulum (ER) stress was induced by DEHP and triggered unfolded protein response (UPR). Interestingly, LYC could effectively ameliorate these "hit". The present study suggested that LYC prevents DEHP-induced ER stress in testis via regulating NXRs and UPRER.

Role of mitochondria-endoplasmic reticulum coupling in lycopene preventing DEHP-induced hepatotoxicity

Di (2-ethylhexyl) phthalate (DEHP) is a hazardous compound used as a plasticizer in plastic products. As a natural carotenoid, lycopene (LYC) is considered an effective protective agent against various types of organ damage. The present study aimed to investigate the role of mitochondria-endoplasmic reticulum (ER) coupling in LYC preventing DEHP-induced hepatotoxicity. The mice were treated with LYC (5 mg kg^-1) and/or DEHP (500 or 1000 mg kg^-1). In the present study, LYC prevented DEHP-induced histopathological changes including fibrosis and glycogen storage in the liver. Additionally, LYC alleviated DEHP-induced ultrastructural injury of mitochondria and ER. LYC had the underlying preventability against DEHP-induced mitochondrial dynamics imbalance including an increase in fission and a decrease in fusion. Furthermore, DEHP induced mitochondria-associated endoplasmic reticulum membrane (MAM) disorder-induced ER stress through the ER unfolded protein response (UPR^ER), but LYC alleviated these alterations. Therefore, LYC prevented DEHP-induced hepatic mitochondrial dynamics and MAM disorder, leading to ER stress. The present study provides novel evidence of mitochondria-ER coupling as a target for LYC that prevents DEHP-induced hepatotoxicity.

Effects of bisphenol A exposure during cardiac cell differentiation

Heart development requires a precise temporal regulation of gene expression in cardiomyoblasts. Therefore, the transcriptional changes in differentiating cells can lead to congenital heart diseases. Although the genetic mutations underlie most of these alterations, exposure to environmental contaminants, such as bisphenol A (BPA), has been recently considered as a risk factor as well. In this study we investigated the genotoxic and epigenotoxic effects of BPA throughout cardiomyocyte differentiation. H9c2 cells (rat myoblasts) were exposed to 10 and 30 μM BPA before and during the last two days of cardiac-driven differentiation. Then, we have analysed the phenotypic and molecular modifications (at transcriptional, genetic and epigenetic level). The results showed that treated myoblasts developed a skeletal muscle cell-like phenotype. The transcriptional changes induced by BPA in genes codifying proteins involved in heart differentiation and function depend on the window of exposure to BPA. The exposure before differentiation repressed the expression of heart transcription factors (Hand2 and Gata4), whereas exposure during differentiation reduced the expression of cardiac-specific genes (Tnnt2, Myom2, Sln, and Atp2a1). Additionally, significant effects were observed regarding DNA damage and histone acetylation levels after the two periods of BPA exposure: in cells exposed to the toxicant the percentage of DNA repair foci (formed by the co-localization of γH2AX and 53BP1) increased in a dose-dependent manner, whereas the treatment with the toxicant triggered a decrease in the epigenetic marks H3K9ac and H3K27ac. Our in vitro results reveal that BPA seriously interferes with the process of cardiomyocyte differentiation, which could be related to the reported in vivo effects of this toxicant on cardiogenesis.

Impact of Heavy Metals on Human Male Fertility-An Overview

Heavy metals are endocrine disruptors which interfere with processes mediated by endogenous hormones of the organism, negatively affecting endocrine functions. Some studies have correlated heavy metal exposure with male infertility. However, the number of studies conducted on humans are limited. Therefore, the aim of this study is to summarize the current knowledge on how heavy metals influence human male fertility. Hence, three distinct databases were consulted—PubMed, Scopus and Web of Science—using single keywords and combinations of them. The total number of identified articles was 636. Nevertheless, by using the inclusion and exclusion criteria, 144 articles were finally included in this work. Results display that the development of adequate instruments for heavy metal assessment may play an important function in human male fertility diagnosis and treatment. Furthermore, clinical trials could be useful to confirm the role of heavy metals in human male fertility diagnosis. Overall, further research is required to fully understand the molecular and cellular basis of the influence of environmental and occupational exposure to heavy metals on human male infertility and reproductive outcomes.

Assessment of DNA damage in relation to heavy metal induced oxidative stress in females with recurrent pregnancy loss (RPL)

Pregnancy termination consecutively for three or more times during the first trimester is termed as Recurrent pregnancy loss (RPL). In addition to the abnormal karyotype, heavy metal induced oxidative damage may contribute as prominent etiological factor in pregnancy termination. Oxidative stress is considered crucial in etiology underlying RPL with altered antioxidant status and subsequent DNA damage. The current case controlled study investigated Total antioxidant capacity (TAC), DNA damage (8OHdG) and heavy metals in RPL group (n = 30) and the women with successful pregnancies and no cases of miscarriage as control group (30 women). Heavy metals -Antimony (Sb) and Arsenic (As) were measured by Inductively Coupled Plasma Mass spectrophotometry (ICP-MS). There was significant decrease in levels of TAC in RPL group compared to healthy pregnant women (P < 0.05). On contrary, elevated levels of As and Sb were observed in RPL group with subsequent increase in the levels of 8OHdG (P < 0.001); indicating extensive DNA damage in these patients. Furthermore, increased levels of As and Sb in RPL group were positively correlated with 8OHdG and negatively with total antioxidant capacity. The outcome of the study provides clear insight of the role of metal induced oxidative stress that plays a vital role in the pathophysiology underlying RPL.

Temephos decreases sperm quality and fertilization rate and is metabolized in rat reproductive tissues at low dose exposure

Temephos is an organophosphorus (OP) pesticide used in control campaigns against vectors that transmit diseases, including dengue, a public health concern. The WHO classifies temephos in category III and its safe concentration (LOAEL) in male rats is 100 mg/kg/day for up to 44 days. Temephos inhibits acetylcholinesterase (AChE) and is metabolized in different tissues, probably by mixed-function oxidases; one of its metabolites is bisphenol S (BPS), which is considered an endocrine disruptor. The aim of this study was to evaluate the effects of temephos on sperm function and its biotransformation in the testis, epididymis, and other tissues to explore its toxicity in rats treated with 100 mg/kg/day/5 or 7 days (gavage). AChE activity was inhibited 70% starting on day 3 and 13 or 41% mortality was observed at 5 or 7 days, respectively. After 7 days, temephos significantly decreased sperm motility (30%) and viability (10%) and increased (10%) lipoperoxidation, and the sperm DNA exhibited no damage. Temephos was distributed and metabolized in all tissues, with the highest levels observed in the adipose tissue and temephos levels were 16-fold higher in the epididymis than in the testis. Notably, BPS was observed in the testis. At 5 days, decreased sperm motility (12.5%) and viability (5.7%) were observed and sperm fertilization decreased (30%). These results suggest that temephos decreases sperm quality and fertilization capacity at recommended safe concentrations and that it is metabolized in male reproductive tissues. This pesticide places the reproductive health of exposed people at risk, suggesting the need to reevaluate its toxicity.

Exposure to the bromodomain inhibitor N-methyl pyrrolidone blocks spermatogenesis in a hormonal and non-hormonal fashion

N-methyl pyrrolidone (NMP) is an FDA approved molecule used as an excipient in pharmaceutical industry. Besides having a central role in formulation of drugs, the most important function of any excipient is to guarantee the safety of the medicine during and after its administration. Several studies have shown that exposure to NMP and especially in rats produce a gonadotoxic effect leading to infertility. However, the mechanisms underlying the effect of NMP on male reproduction are unknown. The aim of this study was to assess the reproductive toxicity of NMP in male rats and to elucidate the underlying mechanism. Male Sprague Dawley rats were injected intraperitoneally, twice/ week, at a dose of 108 mg/ 100 g of body weight with NMP. Analysis of reproductive parameters revealed testicular atrophy in NMP treated animals compared to control animals. Germ cell composition within the seminiferous tubules was disturbed and manifested in an increase in number of cells with fragmented DNA. A subsequent decrease in number of spermatocytes and spermatids was observed. Alpha screen assay shows that NMP acts at the concentrations we applied in vivo as a low affinity inhibitor for BRDT (testis specific bromodomain protein). BRDT inhibition is mirrored by a significant decrease in the expression of early stage spermatocyte markers (lmna, aurkc and ccna1), during which BRDT expression predominates. A significant decrease in testosterone levels was also observed. Since NMP interferes with spermatogenesis on various levels, its use in humans must be carefully monitored.

Aristolochic acid I induces impairment in spermatogonial stem cell in rodents

Aristolochic acid I (AAI) is a natural bioactive substance found in plants from the Aristolochiaceae family and impairs spermatogenesis. However, whether AAI-induced spermatogenesis impairment starts at the early stages of spermatogenesis has not yet been determined. Spermatogonial stem cells (SSCs) are undifferentiated spermatogonia that balance self-renewing and differentiating divisions to maintain spermatogenesis throughout adult life and are the only adult stem cells capable of passing genes onto the next generation. The objective of this study was to investigate whether AAI impairs SSCs during the early stages of spermatogenesis. After AAI treatment, we observed looser, smaller and fewer colonies, decreased cell viability, a decreased relative cell proliferation index, and increased apoptosis in SSCs in a concentration- and/or time-dependent manner. Additionally, AAI promoted apoptosis in SSCs, which was accompanied by upregulation of caspase 3, P53 and BAX expression and downregulation of Bcl-2 expression, and suppressed autophagy, which was accompanied by upregulation of P62 expression and downregulation of ATG5 and LC3B expression, in a concentration-dependent manner. Then we found that AAI impaired spermatogenesis in rats, as identified by degeneration of the seminiferous epithelium, and increased apoptosis of testicular cells. Taken together, our findings demonstrate that AAI causes damage to SSCs and implicate apoptosis and autophagy in this process. The impairment of SSCs may contribute to AAI-induced testicular impairment. Our findings provide crucial information for the human application of botanical products containing trace amounts of AAI.

Iprodione and chlorpyrifos induce testicular damage, oxidative stress, apoptosis and suppression of steroidogenic- and spermatogenic-related genes in immature male albino rats

The fungicide iprodione (IPR) and the insecticide chlorpyrifos (CPF) are concurrently applied for early disease control in fruits and other crops. However, there are no available data about the impacts of their co-exposure. Additionally, IPR and CPF are known as endocrine disruptors that can cause reproductive toxicity. The outcomes of their co-exposure on the development of male reproductive organs are still unknown. Therefore, this study aimed to assess the risk of exposure to these pesticides, particularly on the postnatal development of the male albino rat reproductive system from postnatal days 23-60. The results revealed that a single IPR or CPF exposure has harmful consequences on the reproductive development and function manifested by reduced testicular weight, serious changes in sperm characteristics, reproductive hormone level imbalance, testicular enzymes, oxidative stress and apoptosis-related enzymes, which correlated with transcription levels of steroidogenic- and spermatogenic-related genes. Histopathologically, both compounds caused severe damage in the testis and accessory glands architecture. Notably, co-exposure to IPR and CPF in rats caused more serious damage, indicative of an additive effect than individual exposure, so concurrent exposure should be avoided as it is more hazardous, especially on male fertility.

Pollutants and sperm quality: a systematic review and meta-analysis

Male fertility and semen quality have declined over recent decades. Among other causes, exposure to environmental and occupational pollution has been linked to adverse reproductive outcomes, but effects on male semen quality are still uncertain. Therefore, the aim of the present study was to conduct a systematic review and meta-analysis to assess current evidence regarding the impact of exposure to tobacco smoke and environmental and occupational pollution on sperm quality in humans. In the meta-analysis, 22 studies are included showing that environmental and occupational pollutants may affect sperm count, volume, concentration, motility, vitality and sperm DNA, and chromatin integrity. All included articles reported significant alterations in at least one of the outcomes studied in association with at least one of the pollutants studied. Considering that sperm quality can be considered a proxy for general health and that pollutants have a dramatic impact on climate change, it would be strongly recommended to better understand the role of pollutants on human, animal, and planetary health.

The Effect of Lead Acetate and Quercetin on the Tight and Gap Junctions in the Mouse Testis

Environmental pollutant effects on fertility sometime are irretrievable. The aim of this study was to investigate the effect of lead acetate and quercetin on tight (claudin 11 and occludin) and gap junctional (connexin 43) proteins and the integrity of the blood-testis barrier status. Experimental groups, including the lead acetate (Pb), quercetin (QE), lead acetate with quercetin (Pb + QE), and control mice, were treated at least one spermatogenic cycle. Gene expression of claudin 11 and occludin decreased in Pb + QE, Pb, and QE compared with the control group. Connexin 43 (Cx43) expression in the control and Pb groups was lower than in Pb + QE and QE. The immunohistochemical data were generally in line with these findings. In conclusion, the results showed that Pb exposure led to disorders in cellular interactions that affect testicular function; however, simultaneous treatment with quercetin did not alleviate these effects. Graphical Abstract.

Selenium sources differ in their potential to alleviate the cadmium-induced testicular dysfunction

Cadmium (Cd), a major environmental contaminant, is closely associated with male reproductive health. Selenium (Se) has been recognized as an effective chemo-protectant against Cd toxicity, but the underlying mechanisms remain unclear. The objective of present study was to illustrate the toxic effect of Cd on testis, and then compare the antagonistic effect among different Se sources on growth performance, testicular damage, ion homeostasis, antioxidative potential, and the expression of selenotranscriptome and biosynthetic related factors in Cd-treated chicken. Male chickens were fed with (Ⅰ) Control group: basal diet; (Ⅱ) Cd group: basal diet with 140 mg/kg CdCl₂; (Ⅲ) YSe + Cd group: basal diet with 140 mg/kg CdCl₂ and 3 mg/kg Yeast-Se; (Ⅳ) NSe + Cd group: basal diet with 140 mg/kg CdCl₂ and 1 mg/kg Nano-Se; (Ⅴ) SSe + Cd group: basal diet with 140 mg/kg CdCl₂ and 3 mg/kg Na₂SeO₃. It was observed that different Se treatments dramatically alleviated Cd-induced testicular developmental disorder, ion homeostasis disorder, hormone secretion disorder and oxidative stress. Simultaneously, Se mitigated Cd-induced testicular toxicity by regulating selenoprotein biosynthetic related factors to promote selenoprotein transcription. Finally, this study indicated that dietary supplementation of Yeast-Se produced an acceptable Se form to protect testis from Cd exposure.

Phthalate exposure and semen quality in infertile male population from Tianjin, China: Associations and potential mediation by reproductive hormones

Global decline in male fertility and their associations with ubiquitous exposure of phthalates (PAEs) have raised public concerns. However, the current epidemiological data are limited and controversial. Hence, we investigated possible associations between PAE exposure and male infertility. Eleven phthalate metabolites (mPAEs) were determined in urine and serum samples collected from eighty-eight males diagnosed with infertility from Tianjin, China. The median serum levels of mPAE were n.d. -3.63 ng/mL, which were 1-2 orders of magnitude lower than the urinary levels of n.d. -192 ng/mL. Negative associations were identified between urinary follicle-stimulating hormone (FSH) and MiBP and serum MCMHP, as well as testosterone (T) and luteinizing hormone (LH) and the molar concentrations of ∑mPAE, while positive association was found between T and the serum molar concentrations of ∑mDEHP. Positive associations were found between the molar concentrations of serum ∑mPAE and sperm concentration, sperm motility rate, and progressive motility, between mono (2-ethyl-5-carboxypentyl) phthalate (MECPP) and semen volume and total sperm number, and between MCMHP and progressive motility, while negative association was found between mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) and progressive motility. Moreover, FSH was found to mediate the association between serum concentrations of MCMHP and progressive motility (mediation ratio = 41.6%), and LH to mediate the associations between serum concentrations of ∑mPAE and sperm concentration (mediation ratio = 45.7%) and sperm motility rate (mediation ratio = 29.0%). These results also suggested that serum levels of mPAE are a good predictor for male infertility. Further efforts need to be made on toxicological studies to systematically elaborate the internal mechanisms.

Effects of Cadmium, Lead, and Mercury on the Structure and Function of Reproductive Organs

Reproductive organs are essential not only for the life of an individual but also for the survival and development of the species. The response of reproductive organs to toxic substances differs from that of other target organs, and they may serve as an ideal “barometer” for the deleterious effects of environmental pollution on animal and human health. The incidence of infertility, cancers, and associated maladies has increased in the last fifty years or more, while various anthropogenic activities have released into the environment numerous toxic substances, including cadmium, lead, and mercury. Data from epidemiological studies suggested that environmental exposure to cadmium, lead, and mercury may have produced reproductive and developmental toxicity. The present review focused on experimental studies using rats, mice, avian, and rabbits to demonstrate unambiguously effects of cadmium, lead, or mercury on the structure and function of reproductive organs. In addition, relevant human studies are discussed. The experimental studies reviewed have indicated that the testis and ovary are particularly sensitive to cadmium, lead, and mercury because these organs are distinguished by an intense cellular activity, where vital processes of spermatogenesis, oogenesis, and folliculogenesis occur. In ovaries, manifestation of toxicity induced by cadmium, lead, or mercury included decreased follicular growth, occurrence of follicular atresia, degeneration of the corpus luteum, and alterations in cycle. In testes, toxic effects following exposure to cadmium, lead, or mercury included alterations of seminiferous tubules, testicular stroma, and decrease of spermatozoa count, motility and viability, and aberrant spermatozoa morphology.

lncRNA involved in triptonide-induced cytotoxicity in mouse germ cells

Triptonide reportedly has strong antitumor and anti-inflammatory activities. However, its severe toxicity, including to the reproductive system, has greatly restricted its use in patients who wish to preserve fertility. lncRNAs play crucial roles in male fertility and reportedly regulate triptonide's antitumor activity. However, whether lncRNAs are involved in triptonide-induced reproductive toxicity is unknown. Here, we showed that triptonide induced significant cytotoxicity, as demonstrated by reduced cell viability and induction of apoptosis and autophagy in mouse germ cells (a spermatocyte cell line, GC2). The expression levels of numerous lncRNAs and mRNAs in GC2 cells were altered at the transcriptome level after treatment with triptonide for 24 h, as determined by RNA sequencing. Gene ontology and pathway analyses showed that the functions of the differentially expressed lncRNAs and mRNAs were closely linked with many processes, including gene expression regulation, cell death, cell cycle regulation, cell proliferation and development and others. After validating our RNA-seq data, we selected one lncRNA, Obox4-ps35, dramatically induced by triptonide for further investigation. Obox4-ps35 knock-out aggravated triptonide-induced cytotoxicity by decreasing cell survival and increasing apoptosis and autophagy rates. These data suggest that germ cells exposed to triptonide overexpress Obox4-ps35 to protect against triptonide-induced cytotoxicity. This study provides preliminary evidence and novel directions for exploring roles of lncRNAs in triptonide-induced cytotoxicity, especially in reproductive toxicity.

Involvement of oxidative stress in ZnO NPs-induced apoptosis and autophagy of mouse GC-1 spg cells

Zinc oxide nanoparticles (ZnO NPs) have been extensively used in various industries and reported to inhibit spermatogenesis, however, ZnO NPs-induced spermatogenesis failure is yet to be fully elucidated. Herein, mouse-derived spermatogonia cell line GC-1 spg cells were treated with ZnO NPs for 24 h in the presence or absence of radical scavenger N-acetyl-L-cysteine (NAC) or autophagy inhibitor 3-methyladenine (3-MA), then cell viability was observed by MTT assay; apoptosis was observed by western blotting analysis and AnnexinV-FITC/PI assay, respectively; autophagy was detected by western blotting analysis and transmission electron microscopy, respectively; and the contents of MDA and GSH and the activities of SOD and GSH-PX were measured by oxidative stress kits. The present study showed that ZnO NPs exposure inhibited viability and induced apoptosis of mouse GC-1 spg cells. Intriguingly, ZnO NPs markedly increased the protein content of LC3-II, the ratio of LC3-II/LC3-I, and the protein levels of ATG 5 and Beclin 1 in the cells. Furthermore, transmission electron microscopy (TEM) showed that autophagic vesicles in the cytoplasm increased significantly in the ZnO NPs-treated cells, indicating that ZnO NPs could induce autophagy of the cells. Oxidative stress could be induced by ZnO NPs; moreover, inhibition of oxidative stress could alleviate the induction of apoptosis and autophagy by ZnO NPs. Inhibition of autophagy by 3-MA could rescue the inhibition of cell viability and induction of apoptosis by ZnO NPs, which indicated that autophagy might have cytotoxic effect on ZnO NPs-induced apoptosis. In summary, oxidative stress was involved in ZnO NPs-induced apoptosis and autophagy of mouse GC-1 spg cells, and autophagy might play a cytotoxic role in ZnO NPs-induced apoptosis.

Interaction effect of polycyclic aromatic hydrocarbon metabolites and cadmium on semen quality in nonsmokers

Both cadmium (Cd) and polycyclic aromatic hydrocarbons (PAHs) are known reproductive toxicants, but their co-exposure and interaction effect on semen quality particularly in nonsmokers remain unknown. We included 333 nonsmoking men and analyzed their urine and semen samples for heavy metals and PAH metabolites. Restricted cubic spline models were used to explore the dose-response relationship between each OH-PAHs, Cd, and semen quality parameters; the generalized linear model was performed to examine the interaction of each urinary OH-PAH metabolite and Cd concentration on semen quality. Also, stratified analysis was applied to further illustrate the independent effect of PAHs on semen quality parameters in low and high concentration Cd subgroups. The dose-response and interaction effect of PAHs and Cd on male semen quality was observed. Stratified analysis in the high concentration Cd subgroup showed a negative association of 1-OHPyr concentration with semen motility. Our findings indicate that Cd not only modifies the association between PAHs and semen quality but can also exacerbate the toxic effect of pyrene on semen quality parameters. However, further studies with larger samples are needed to confirm the findings.

Chlorpyrifos inhibits sperm maturation and induces a decrease in mouse male fertility

BACKGROUND

Pesticides, especially organophosphorus pesticides such as chlorpyrifos (CPF), play an important role in modern agriculture. Studies have shown that pesticide residues are an important cause of male reproductive injury in mammal.

AIM

The aim of this study was to evaluate the reproductive damage caused by CPF in male mice and investigate the underlying mechanisms.

METHODS

In vivo, C57BL/6 mice (6-8 weeks old) were treated with CPF for 14, 70, and 80 days by intraperitoneal injection, intragastric administration, and dietary supplementation, respectively. Then, sperm from the cauda epididymidis was cultured in vitro to confirm the deleterious effects of CPF.

RESULTS

The in vivo results indicated that, after treatment with CPF by dietary supplementation and intraperitoneal injection, the expression of reproduction-related genes in the mouse testes was altered, although the mice were fertile and the testes presented no morphological abnormalities. Notably, mating experiments revealed that the fertility of male mice was decreased following CPF administration by gavage. Sperm motility within the cauda epididymidis declined significantly after CPF treatment, which was accompanied by a decrease in sperm density, upregulation of relative reactive oxygen species (ROS) levels, and downregulation of glutathione reductase activity. In vitro incubation experiments showed that sperm rapidly lost their capacity for linear movement; the relative ROS levels also increased significantly, while the mitochondrial membrane potential (MMP) showed a significant decrease. However, the integrity of the plasma membrane was not affected by CPF administration.

CONCLUSIONS

The above data indicated that exposure to CPF reduces sperm motility by disrupting mitochondrial function and increasing the level of oxidative stress during sperm maturation, thereby reducing the fecundity of male mice.

Cell membrane-related toxic responses and disruption of intercellular communication in PCB mechanisms of toxicity: A review

An understanding of polychlorinated biphenyl (PCB) congener-specific effects on cell membrane and intercellular communication is important within the studies of PCB absorption, organ-related PCB accumulation and exertion of toxic responses. Toxic potential of PCBs is linked to various deleterious effects on human health, including neurotoxicity, immunotoxicity, reproductive toxicity and genotoxicity and, recently in 2016 International Agency for Research on Cancer (IARC) has upgraded the classification of PCBs to Group 1 "Carcinogenic to humans." Proposed mechanisms of aforementioned PCBs adverse effects at cellular membrane level are: (i) downregulation of gap junction intercellular communication and/or connexins; (ii) compromised membrane integrity; and (iii) altered tight junction barrier function. This study, based on an extensive literature survey, shows the progress in scientific research of each of these three levels with the aim of pointing out the earliest toxic events of PCBs, which can result in serious cell/tissue/organ damage.

Effects of Myo-inositol Alone and in Combination with Seleno-Lmethionine on Cadmium-Induced Testicular Damage in Mice

BACKGROUND

Cadmium (Cd) impairs gametogenesis and damages the blood-testis barrier.

OBJECTIVE

As the primary mechanism of Cd-induced damage is oxidative stress, the effects of two natural antioxidants, myo-inositol (MI) and seleno-L-methionine (Se), were evaluated in mice testes.

METHODS

Eighty-four male C57 BL/6J mice were divided into twelve groups: 0.9% NaCl (vehicle; 1 ml/kg/day i.p.); Se (0.2 mg/kg/day per os); Se (0.4 mg/kg/day per os); MI (360 mg/kg/day per os); MI plus Se (0.2 mg/kg/day); MI plus Se (0.4 mg/kg/day); CdCl2 (2 mg/kg/day i.p.) plus vehicle; CdCl2 plus MI; CdCl2 plus Se (0.2 mg/kg/day); CdCl2 plus Se (0.4 mg/kg/day); CdCl2 plus MI plus Se (0.2 mg/kg/day); and CdCl2 plus MI plus Se (0.4 mg/kg/day). After 14 days, testes were processed for biochemical, structural and immunohistochemical analyses.

RESULTS

CdCl2 increased iNOS and TNF-α expression and Malondialdehyde (MDA) levels, lowered glutathione (GSH) and testosterone, induced testicular lesions, and almost eliminated claudin-11 immunoreactivity. Se administration at 0.2 or 0.4 mg/kg significantly reduced iNOS and TNF-α expression, maintained GSH, MDA and testosterone levels, structural changes and low claudin-11 immunoreactivity. MI alone or associated with Se at 0.2 or 0.4 mg/kg significantly reduced iNOS and TNF-α expression and MDA levels, increased GSH and testosterone levels, ameliorated structural organization and increased claudin-11 patches number.

CONCLUSION

We demonstrated a protective effect of MI, a minor role of Se and an evident positive role of the association between MI and Se on Cd-induced damages of the testis. MI alone or associated with Se might protect testes in subjects exposed to toxicants, at least to those with behavior similar to Cd.

Aluminum, at an environmental concentration, associated with acidic pH and high water temperature, causes impairment of sperm quality in the freshwater teleost Astyanax altiparanae (Teleostei: Characidae)

Given the toxicity of metals, including aluminum (Al), and the effects of water temperature on ectotherms, we investigated the individual or association effect of these variables (Al + acidic pH + temperature changes) on sperm quality of Astyanax altiparanae. Mature males were divided into nine experimental groups based on the combination of each of three water temperatures (20, 25, and 30 °C) with neutral and acidic pH values (7.0 and 5.5, respectively) with or without 0.5 mg L^-1 Al. The fish were subjected to subacute, semi-static exposure and at 24 and 96 h were evaluated for seminal parameters: (1) pH; (2) osmolality; (3) sperm concentration; (4) sperm morphology; (5) sperm kinetics; and (6) sperm ultrastructure. At 30 °C, Al caused a reduction in osmolality (24 and 96 h) and sperm concentration (24 h). When analysing sperm kinetics (30 s post-activation), Al caused a reduction in total motility at all temperatures (24 h), and when this exposure time was longer (96 h), both acidic pH and Al addition to the water caused sperm motility reduction. By analysing curvilinear velocity (VCL) 30 s after sperm activation (24 and 96 h), the acidic pH caused a reduction in sperm movement at 20 and 30 °C, but at 25 °C Al triggered this reduction. Finally, Al in the water caused ultrastructural changes in the sperm head, midpiece, and flagella regardless of water temperature. Also, it was found that the combination of Al at 30 °C caused a reduction in sperm head area while at 20 °C, Al triggered a reduction in the midpiece area. Therefore, acidity influenced some A. altiparanae sperm parameters but Al in the water accentuated these effects on seminal quality, especially seminal osmolality and sperm concentration, kinetics, and ultrastructure. This toxicity was also influenced by changes in water temperature.

Maternal exposure to Di-(2-ethylhexyl) phthalate (DEHP) activates the PI3K/Akt/mTOR signaling pathway in F1 and F2 generation adult mouse testis

Di-(2-ethylhexyl) phthalate (diethylhexyl phthalate, DEHP) can cause male reproductive damage in rodents and human. Moreover, DEHP is known to promote transgenerational inheritance of adult-onset disease in subsequent generations after maternal exposure during fetal gonadal development. The PI3K/Akt/mTOR signaling pathway has been implicated in germ cell survival following testicular damage. In this study, a F0 gestation DEHP exposure and transgenerational inheritance testis injury model was established to study the testis injury phenotype and the expression and activation of members of PI3K/Akt/mTOR signaling pathway in the testis of F1-F3 generation mice. We found that the bodyweight and the anogenital distance (AGD) are reduced only in F1 mice, the sperm motility and deformity decreased in F1-F3 mice, and the testicular histomorphology damagedin F1-F3 mice; however the sperm motility and deformity rates are increased and the histomorphological injury is repaired during the transgenerational process. We also found the activation of PI3K/Akt/mTOR signaling pathway is enhanced in F1 and F2, and the number of apoptotic cells is decreased in F3 generation mice compared to the control group. These results suggest that the PI3K/Akt/mTOR signaling pathway may be activated to promote the proliferation and differentiation and protect testicular cells from apoptosis in the F1 and F2 generation mice after direct exposure to DEHP.