Male Reproductive System Research Articles

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.

Prognosis and diagnosis of prostate cancer based on hypergraph regularization sparse least partial squares regression algorithm.

Prostate cancer (PCa) is a malignant tumor of the male reproductive system, and its incidence has increased significantly in recent years. This study aimed to further identify candidate biomarkers with prognostic and diagnostic significance by integrating gene expression and DNA methylation data from PCa patients through association analysis. To this end, this paper proposes a sparse partial least squares regression algorithm based on hypergraph regularization (HR-SPLS) by integrating and clustering two kinds of data. Next, module 2, with the most significant weight, was selected for further analysis according to the weight of each module related to DNA methylation and mRNAs. Based on the DNA methylation sites in module 2, this paper uses multiple machine learning methods to construct a PCa diagnosis-related model of 10-DNA methylation sites. The results of Receiver Operating Characteristic (ROC) analysis showed that the DNA methylation-related diagnostic model we constructed could diagnose PCa patients with high accuracy. Subsequently, based on the mRNAs in module 2, we constructed a prognostic model for 7-mRNAs (MYH11, ACTG2, DDR2, CDC42EP3, MARCKSL1, LMOD1, and MYLK) using multivariate Cox regression analysis. The prognostic model could predict the disease free survival of PCa patients with moderate to high accuracy (area under the curve (AUC) =0.761). In addition, Gene Set EnrichmentAnalysis (GSEA) and immune analysis indicated that the prognosis of patients in the risk group might be related to immune cell infiltration. Our findings may provide new methods and insights for identifying disease-related biomarkers by integrating DNA methylation and gene expression data.

Effects of Chicory (Cichorium intybus L.) Extract on Male Rat Reproductive System, Pregnancy and Offspring Development.

We recently reported that extract prepared from the aerial part of Cichorium intybus L. (CE) possesses hepatoprotective, hypolipidemic, and hypoglycemic properties. This paper focuses on the effects of CE on the male rat reproductive system and the effects of this treatment on pregnancy and offspring development. The experimental male rats received 100 mg/kg bw/day, 500 mg/kg bw/day, and 1000 mg/kg bw/day of CE orally for 60 consecutive days. Rats that received tap water were used as controls. After treatment, we evaluated the effects of CE on the male reproductive system, fertility, and offspring development. For CE-treated male rats, there was a significant increase in the (1) diameter of seminiferous tubules, (2) spermatogenic index, (3) number of total and motile spermatozoa, and (4) testosterone levels. Additionally, there was a decrease in the pre- and post-implantation death of the embryos in the CE-treated group. All pups born from CE-treated males demonstrated normal development. CE treatment significantly improved male reproductive functions. No adverse effects on pregnancy and offspring development were observed when males were treated with CE. Further clinical evaluation of CE should lead to the development of a safe and effective phytodrug for treating male infertility.

Cannabidiol impairs sperm quality and function in adult mice

BackgroundConsidering the growing therapeutic use of cannabidiol as well as the presence of cannabinoid receptors in sperm and its possible genotoxic activity, the effect of cannabidiol on sperm quality and function was examined.MethodsThirty male NMRI mice were randomly divided into three groups: control (no injection), sham (intraperitoneal (IP) injection of DMSO daily for 34 days), and cannabidiol (IP injection of cannabidiol 30 mg/ml daily for 34 days). Following 35 days after the last injection, sperm parameters, chromatin integrity (CMA3 staining), acrosome reaction (FITC-PNA method), fertility-related genes (IZUMO1, PLCζ), and blastulation rate of the embryos obtained from the oocytes fertilized with the mentioned sperms was investigated.ResultsCount, motility, and morphology of sperm were not significantly affected by cannabidiol. CMA3+ sperms (protamine deficiency) were significantly higher in the cannabidiol group compared to the control group (P = 0.03). The acrosomal reaction and fertility-related genes (IZUMO1, PLCζ) in the cannabidiol group did not differ significantly compared to the control group. Also, there was no significant difference between the cannabidiol group and the control group in the two-cell and the eight-cell stages but the rate of blastocyst formation was significantly lower in the cannabidiol group compared to other groups (P < 0.0001).ConclusionsOur results showed that cannabidiol leads to negative effects on the male reproductive system through an effect on sperm chromatin and the rate of reaching the blastocyst stage of the embryo.Graphical

Integrative Assessment of Seminal Plasma Biomarkers: A Narrative Review Bridging the Gap between Infertility Research and Clinical Practice.

Infertility represents a significant global health challenge impacting millions of couples worldwide. Approximately half of all infertile couples exhibit compromised semen quality, indicative of diminished male fertility. While the diagnosis of male infertility traditionally relies on semen analysis, its limitations in providing a comprehensive assessment of male reproductive health have spurred efforts to identify novel biomarkers. Seminal plasma, a complex fluid containing proteins, lipids, and metabolites, has emerged as a rich source of such indicators. Reproduction depends heavily on seminal plasma, the primary transporter of chemicals from male reproductive glands. It provides a non-invasive sample for urogenital diagnostics and has demonstrated potential in the identification of biomarkers linked to illnesses of the male reproductive system. The abundance of seminal proteins has enabled a deeper understanding of their biological functions, origins, and differential expression in various conditions associated with male infertility, including azoospermia, asthenozoospermia, oligozoospermia, teratozoospermia, among others. The true prevalence of male infertility is understated due to the limitations of the current diagnostic techniques. This review critically evaluates the current landscape of seminal plasma biomarkers and their utility in assessing male infertility. Βy bridging the gap between research and clinical practice, the integrative assessment of seminal plasma biomarkers offers a multimodal approach to comprehensively evaluate male infertility.

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.

Association between serum vitamin D levels and prostate tumor: a systematic review and meta-analysis

Introduction: Prostate cancer is among the most frequent neoplasms of the male reproductive system, and its relationship with serum vitamin D level is a controversial subject. The present study intended to investigate the relationship between serum vitamin D levels and the risk of prostate carcinoma. Materials and Methods: This study is a systematic review and meta-analysis based on the PRISMA tool. The search was conducted in databases Web of Science, Cochrane, ProQuest, PubMed, and Google Scholar Search Engine until December 1, 2023. Data was analyzed using STATA 14 software. Results: There was no significant relationship between serum vitamin D levels lower than 50 nmol/L (vitamin D level &lt;50 nmol/L) and prostate cancer. In Finland, the risk of prostate carcinoma in male individuals with serum vitamin D levels lower than 50 nmol/L was 34% higher (OR: 1.34, 95% CI: 1.14, 1.54). In South Korea, on the other hand, serum vitamin D levels lower than 50 nmol/L prevented prostate cancer (OR: 0.94, 95% CI: 0.90, 0.99). There was no significant relationship between the serum vitamin D levels lower than 50 nmol/L and prostate neoplasm in men aged 60 to 69 years old (OR: 0.95, 95% CI: 0.83, 1.07), in men 50 to 59 years old. On the other hand, serum vitamin D levels lower than 50 nmol/L increased the risk of prostate tumor by 32% (OR: 1.32, 95% CI: 1.13, 1.55). Furthermore, no significant relationship was observed between serum vitamin D levels higher than 50 nmol/L (vitamin D level ≥ 50 nmol/L) and the risk of prostate cancer (OR: 1.06, 95% CI: 0.99, 1.14). Conclusion: Generally, there was no significant relationship between serum vitamin D levels and the risk of prostate carcinoma; however, the relationship in some subgroups was statistically significant. We therefore recommend conducting additional studies on this subject. Registration: This study has been compiled based on the PRISMA checklist, and its protocol was registered on the PROSPERO (ID: CRD42023491012) and Research Registry (UIN: reviewregistry1773) website.

COVID-19 and male fertility: short- and long-term impacts of asymptomatic vs. symptomatic infection on male reproductive potential

BackgroundStudies exploring the effect of COVID-19 on male reproductive system suggest a detrimental association, however with conflicting results. The aim of this study was to assess the association between COVID-19 infection and male reproductive potential including hormone profiles and semen parameters.MethodsThis prospective cohort study included 48 patients with confirmed COVID-19 infection. Patients were subdivided into an asymptomatic group (n = 30) and a group with COVID-19 symptoms (n = 18). Serum hormone levels including testosterone, LH, FSH and estradiol were collected during active infection (baseline, time 0), and at 3 and 6 months following COVID-19 infection. Semen samples (basic semen analysis and oxidation reduction potential) were examined at 3 and 6 months following infection. Student and paired-t tests were used to compare continuous variables between the study groups and across the studied time intervals, respectively. Multivariate binary logistic regression analysis was performed to explore predictors for COVID-19 symptoms during active infection.ResultsPatients with COVID-19 symptoms were significantly older (p = 0.02) and had significantly lower serum testosterone levels (p = 0.01) and significantly higher LH: testosterone ratio (p = 0.01) than asymptomatic patients. Multivariate analysis revealed older age (OR = 1.18, p = 0.03) and lower serum testosterone level (OR = 0.8, p = 0.03) as independent predictors of symptomatic COVID-19 infection. Significant increase in testosterone (p &amp;lt; 0.001 for both) and decrease in LH (p = 0.02, p = 0.007) and LH: testosterone (p = 0.02, p = 0.005) levels were observed at 3 and 6 months in patients with COVID-19 symptoms. Asymptomatic patients demonstrated significant increase in testosterone (p = 0.02) and decrease in LH: testosterone (p = 0.04) levels only at 3 months following COVID-19 infection. No significant differences were observed between the two study groups with regards to the semen analysis results obtained at 3 or 6 months following COVID-19 infection.ConclusionSignificantly lower testosterone values are associated with worse disease severity among men with COVID-19 infection. This association appears to be temporary as a significant increase in testosterone levels are witnessed as early as 3 months following recovery. No significant detrimental effect for COVID-19 infection on testicular sperm production is found in this patient population.

Changes in categorization or nomenclature within neuroendocrine tumors.

The 5th edition of the World Health Organization (WHO) classification of neuroendocrine neoplasms (NENs) is built to achieve a uniform terminology and to define a similar diagnostic scheme across different anatomic locations. Since the 4th edition, a chapter discussing NENs in nonneuroendocrine organs has been introduced, which proposes a binary system for classification segregating well-differentiated neoplasms, termed neuroendocrine tumors (NETs), and poorly differentiated neoplasms, termed neuroendocrine carcinomas (NECs). A grading system for NETs is based on mitotic index and/or Ki-67 index and/or necrosis, depending on the different locations. Although this approach has been already well established in the digestive system, it modifies and homogenizes the classification of NENs in the urinary tract, in female genital organs, and in the male genital system. In the lung and thymus, the double terminology of carcinoid/NET, already introduced in the 5th edition of the WHO classification of thoracic tumors, is endorsed. This approach undoubtedly helps the multidisciplinary approach for the diagnosis and clinical management of patients affected by these neoplasms, without losing site-specific characteristics that influence the clinical and biological behavior of tumors in different anatomical sites. Other major advances of the new WHO scheme are the homogenization of epidemiological data and the correct integration of data from prospective future studies aimed at the definition of molecular profiles and at the identification of tumor type-specific and patient-specific therapeutic approaches.

High Concentration of Iron Ions Contributes to Ferroptosis-Mediated Testis Injury.

In order to explore the effect of excessive iron supplementation on ferroptosis in mouse testes, Kunming mice received injections of varying concentrations of iron. The organ weight, sperm density, and malformation rate were measured. Observations of pathological and ultrastructural alterations in spermatogenic tubules were conducted using haematoxylin eosin (HE) staining and transmission electron microscopy(TEM). Transcript levels of related genes and serum biochemical indicators were measured in mouse testicular tissue. The results showed that higher iron concentration inhibited the growth of mice; reduced the organ coefficients of the testis, heart, and liver; and increased the rate of sperm malformation and mortality. Supplementation with high levels of iron ions can adversely affect the male reproductive system by reducing sperm count, damaging the structure of the seminiferous tubules and causing sperm cell abnormalities. In addition, the iron levels also affected the immune response and blood coagulation ability by affecting the red blood cells, white blood cells and platelets. The results showed that iron ions can affect mouse testicular tissue and induce ferroptosis by altering the expression of ferroptosis-related genes. However, the degree of effect was different for the different concentrations of iron ions. The study also revealed the potential role of deferoxamine in inhibiting the occurrence of ferroptosis. Nevertheless, the damage caused to the testis by deferoxamine supplementation suggests the need for further research in this direction. This study provides reference for reproductive toxicity induced by environmental iron exposure and clarifies the mechanism of reproductive toxicity caused by iron overload and the important role of iron in the male reproductive system.

Bringing light into deep-sea biodiversity: a systematic revision and molecular phylogeny of the genus Scaphander Montfort, 1810 (Gastropoda: Cephalaspidea), with a focus on the Indo-Pacific

Abstract Scaphander is a genus of mostly deep-sea, soft-bottom gastropods distributed nearly worldwide. Its taxonomic history is complex, with 32 species currently accepted, most based on shells only. In this work, we revise the diversity and systematics of Scaphander, with a focus on the Indo-Pacific region, using a detailed morphological study and molecular phylogenetics. Conchological and anatomical characters, such as digestive and male reproductive systems were compared, and original descriptions and type material were investigated. Additionally, molecular species delimitation methods were used, such as Assemble Species by Automatic Partitioning (ASAP) based on the gene cytochrome c oxidase subunit I, and the multispecies coalescent method Species Tree And Classification Estimation, Yarely (STACEY) based on a dataset of five gene markers. Thirty-three Scaphander species were recognized worldwide, 10 still based only on shells. Five species are here described as new to science, namely Scaphander amygdalus sp. nov., Scaphander cornus sp. nov., Scaphander obnubilus sp. nov., Scaphander semicallus sp. nov. and Scaphander solomonensis sp. nov. The most diverse region is the Western Pacific (17 species), followed by the Atlantic (12 species) and the Indian Ocean (7 species).

Tetrabromobisphenol A reduces male rats reproductive organ coefficients and disrupting sexual hormone by causing oxidative stress

Tetrabromobisphenol A (TBBPA) has become a topic of public attention due to its pervasive detection in the environment and organisms in recent decades. However, limited information is available regarding the toxicity of TBBPA on reproductive ability of male mammals. Herein, the reproductive toxicity of TBBPA was investigated in male rats to fill the knowledge gap. In this study, male rats were exposed to TBBPA (0, 10, 100, and 1000 mg/kg) for 6 weeks. Subsequently, body and organ indexes, histopathological evaluation of testis and epididymis, ultrastructural observation of sperm, testosterone and progesterone levels, and oxidative stress indicators were conducted to reveal corresponding mechanisms. Results obtained showed that compare to the control group, the body weight, testes weight, epididymis weight, seminal vesicle and coagulation glands weight of rats in the 1000 mg/kg group lost 8.30%, 16.84%, 20.16%, 19.72% and 26.42%, respectively. Intriguingly, exposure to TBBPA (10, 100, 100 mg/kg) resulted in substantial pathological damage in testis, epididymis and sperm. TBBPA exposure also increased malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents, as well as superoxide dismutase (T-SOD) and catalase (CAT) activities in testicular tissue. What’s more, the testosterone and progesterone levels in male rat serum were significantly decreased after exposure to TBBPA for 6 weeks. Meanwhile, results of molecular docking showed that TBBPA has a strong affinity with estrogen receptors (ERs). These findings demonstrated that TBBPA exposure negatively impacts the reproductive ability of male rats, thus providing new insights for risk assessment for reproductive health under TBBPA exposure.

Harmine exhibits anti-apoptotic properties and reduces diabetes-induced testicular damage caused by streptozotocin in rats.

Diabetes mellitus induces fertility problems in men, mainly because of increased free radicals. Natural resources are effective for male infertility treatment. This study investigated the effects of harmine, an alkaloid available in Peganum harmala L., on the male reproductive system of diabetic rats. We divided 32 rats into four groups, and eight were randomly placed in each group. For diabetes induction, the animals received 50 mg/kg of streptozotocin intraperitoneally. After 1 week, animals received 15 mg/kg of harmine (28 days; intraperitoneal). Histopathological examinations, serum levels of male hormones, levels of nitric oxide (NO) and malondialdehyde (MDA) in the testes, total antioxidant capacity (TAC), insulin serum levels, fasting blood glucose levels, the apoptotic index, and semen analysis were assessed. The diabetes group exhibited morphological changes in testicular tissue, significant decreases in the diameter of the seminiferous tubule, the Johnsen score, testosterone, luteinizing hormone, follicle-stimulating hormone, insulin serum levels, and TAC in testicular tissue (p<0.01). Harmine treatment ameliorated the morphological changes in the testes and improved sperm parameters relative to the diabetes group (p<0.05). The NO and MDA levels in the testes, fasting blood glucose serum levels, and apoptotic index parameters were significantly elevated in the diabetes group, while in the diabetes+harmine group, these parameters were reduced (p<0.01). Harmine protects testicular tissue and sperm against diabetes-induced damage. This effect of harmine is associated with a rebalancing of the antioxidant capacity that subsequently decreases apoptosis in the testes.

Male Reproduction in Spinal Muscular Atrophy (SMA) and the Potential Impact of Oral Survival of Motor Neuron 2 (SMN2) Pre-mRNA Splicing Modifiers.

Spinal muscular atrophy (SMA) is a neuromuscular disease caused by deletions or mutations in the survival of motor neuron 1 (SMN1) gene resulting in reduced levels of SMN protein. SMN protein is produced by cells throughout the body, and evidence suggests that low SMN protein can have systemic implications, including in male reproductive organs. However, a paucity of research exists on this important topic. This article will discuss findings from non-clinical studies on the role of SMN in the male reproductive system; additionally, real-world observational reports of individuals with SMA will be examined. Furthermore, we will review the non-clinical reproductive findings of risdiplam, a small-molecule SMN2 splicing modifier approved for the treatment of SMA, which has widespread distribution in both the central nervous system and peripheral organs. Specifically, the available non-clinical evidence of the effect of risdiplam on male reproductive organs and spermatogenesis is examined. Lastly, the article will highlight available capabilities to assess male fertility as well as the advanced reproductive technologies utilized to treat male infertility. This article demonstrates the need for further research to better understand the impacts of SMA on male fertility and reproduction.

Multi-cellular engineered living systems to assess reproductive toxicology

Toxicants and some drugs can negatively impact reproductive health. Many toxicants haven’t been tested due to lack of available models. The impact of many drugs taken during pregnancy to address maternal health may adversely affect fetal development with life-long effects and clinical trials do not examine toxicity effects on the maternal-fetal interface, requiring indirect assessment of safety and efficacy. Due to current gaps in reproductive toxicological knowledge and limitations of animal models, multi-cellular engineered living systems may provide solutions for modeling reproductive physiology and pathology for chemical and xenobiotic toxicity studies. Multi-cellular engineered living systems, such as microphysiological systems (MPS) and organoids, model of functional units of tissues. In this review, we highlight the key functions and structures of human reproductive organs and well-known representative toxicants afflicting these systems. We then discuss current approaches and specific studies where scientists have used MPS or organoids to recreate in vivo markers and cellular responses of the female and male reproductive system, as well as pregnancy-associated placenta formation and embryo development. We provide specific examples of organoids and organ-on-chip that have been used for toxicological purposes with varied success. Finally, we address current issues related to usage of MPS, emerging techniques for improving upon these complications, and improvements needed to make MPS more capable in assessing reproductive toxicology. Overall, multi-cellular engineered living systems have considerable promise to serve as a suitable, alternative reproductive biological model compared to animal studies and 2D culture.

Adenylate kinase phosphate energy shuttle underlies energetic communication in flagellar axonemes.

The complexities of energy transfer mechanisms in the flagella of mammalian sperm flagella have been intensively investigated and demonstrate significant diversity across species. Enzymatic shuttles, particularly adenylate kinase (AK) and creatine kinase (CK), are pivotal in the efficient transfer of intracellular ATP, showing distinct tissue- and species-specificity. Here, the expression profiles of AK and CK were investigated in mice and found to fall into four subgroups, of which Subgroup III AKs were observed to be unique to the male reproductive system and conserved across chordates. Both AK8 and AK9 were found to be indispensable to male reproduction after analysis of an infertile male cohort. Knockout mouse models showed that AK8 and AK9 were central to promoting sperm motility. Immunoprecipitation combined with mass spectrometry revealed that AK8 and AK9 interact with the radial spoke (RS) of the axoneme. Examination of various human and mouse sperm samples with substructural damage, including the presence of multiple RS subunits, showed that the head of radial spoke 3 acts as an adapter for AK9 in the flagellar axoneme. Using an ATP probe together with metabolomic analysis, it was found that AK8 and AK9 cooperatively regulated ATP transfer in the axoneme, and were concentrated at sites associated with energy consumption in the flagellum. These findings indicate a novel function for RS beyond its structural role, namely, the regulation of ATP transfer. In conclusion, the results expand the functional spectrum of AK proteins and suggest a fresh model regarding ATP transfer within mammalian flagella.

NGF, EPO, and IGF-1 in the Male Reproductive System.

Several studies have demonstrated interesting results considering the implication of three growth factors (GFs), namely nerve growth factor (NGF), erythropoietin (EPO), and the insulin-like growth factor-I (IGF-1) in the physiology of male reproductive functions. This review provides insights into the effects of NGF, EPO, and IGF-1 on the male reproductive system, emphasizing mainly their effects on sperm motility and vitality. In the male reproductive system, the expression pattern of the NGF system varies according to the species and testicular development, playing a crucial role in morphogenesis and spermatogenesis. In humans, it seems that NGF positively affects sperm motility parameters and NGF supplementation in cryopreservation media improves post-thaw sperm motility. In animals, EPO is found in various male reproductive tissues, and in humans, the protein is present in seminal plasma and testicular germ cells. EPO receptors have been discovered in the plasma membrane of human spermatozoa, suggesting potential roles in sperm motility and vitality. In humans, IGF-1 is expressed mainly in Sertoli cells and is present in seminal plasma, contributing to cell development and the maturation of spermatozoa. IGF-1 seems to modulate sperm motility, and treatment with IGF-1 has a positive effect on sperm motility and vitality. Furthermore, lower levels of NGF or IGF-1 in seminal plasma are associated with infertility. Understanding the mechanisms of actions of these GFs in the male reproductive system may improve the outcome of sperm processing techniques.

Microplastic presence in dog and human testis and its potential association with sperm count and weights of testis and epididymis.

The ubiquitous existence of microplastics and nanoplastics raises concerns about their potential impact on the human reproductive system. Limited data exists on microplastics within the human reproductive system and their potential consequences on sperm quality. Our objectives were to quantify and characterize the prevalence and composition of microplastics within both canine and human testes and investigate potential associations with the sperm count, and weights of testis and epididymis. Using advanced sensitive pyrolysis-gas chromatography/mass spectrometry, we quantified 12 types of microplastics within 47 canine and 23 human testes. Data on reproductive organ weights, and sperm count in dogs were collected. Statistical analyses, including descriptive analysis, correlational analysis, and multivariate linear regression analyses were applied to investigate the association of microplastics with reproductive functions. Our study revealed the presence of microplastics in all canine and human testes, with significant inter-individual variability. Mean total microplastic levels were 122.63 µg/g in dogs and 328.44 µg/g in humans. Both humans and canines exhibit relatively similar proportions of the major polymer types, with PE being dominant. Furthermore, a negative correlation between specific polymers such as PVC and PET and the normalized weight of the testis was observed. These findings highlight the pervasive presence of microplastics in the male reproductive system in both canine and human testes, with potential consequences on male fertility.

Leukocytospermia and/or Bacteriospermia: Impact on Male Infertility.

Infertility is a globally underestimated public health concern affecting almost 190 million people, i.e., about 17.5% of people during their lifetime, while the prevalence of male factor infertility is about 7%. Among numerous other causes, the prevalence of male genital tract infections reportedly ranges between 10% and 35%. Leukocytospermia is found in 30% of infertile men and up to 20% in fertile men. Bacterial infections cause an inflammatory response attracting leukocytes, which produce reactive oxygen species (ROS) and release cytokines, both of which can cause damage to sperm, rendering them dysfunctional. Although leukocytospermia and bacteriospermia are both clinical conditions that can negatively affect male fertility, there is still debate about their impact on assisted reproduction outcomes and management. According to World Health Organization (WHO) guidelines, leukocytes should be determined by means of the Endtz test or with monoclonal antibodies against CD15, CD68 or CD22. The cut-off value proposed by the WHO is 1 × 106 peroxidase-positive cells/mL. For bacteria, Gram staining and semen culture are regarded as the "gold standard", while modern techniques such as PCR and next-generation sequencing (NGS) are allowing clinicians to detect a wider range of pathogens. Whereas the WHO manual does not specify a specific value as a cut-off for bacterial contamination, several studies consider semen samples with more than 103 colony-forming units (cfu)/mL as bacteriospermic. The pathogenic mechanisms leading to sperm dysfunction include direct interaction of bacteria with the male germ cells, bacterial release of spermatotoxic substances, induction of pro-inflammatory cytokines and ROS, all of which lead to oxidative stress. Clinically, bacterial infections, including "silent" infections, are treatable, with antibiotics being the treatment of choice. Yet, non-steroidal antiphlogistics or antioxidants should also be considered to alleviate inflammatory lesions and improve semen quality. In an assisted reproduction set up, sperm separation techniques significantly reduce the bacterial load in the semen. Nonetheless, contamination of the semen sample with skin commensals should be prevented by applying relevant hygiene techniques. In patients where leukocytospermia is detected, the causes (e.g. infection, inflammation, varicocele, smoking, etc.) of the leukocyte infiltration have to be identified and addressed with antibiotics, anti-inflammatories or antioxidants in cases where high oxidative stress levels are detected. However, no specific strategy is available for the management of leukocytospermia. Therefore, the relationship between bacteriospermia and leukocytospermia as well as their specific impact on functional sperm parameters and reproductive outcome variables such as fertilization or clinical pregnancy must be further investigated. The aim of this narrative review is to provide an update on the current knowledge on leukocytospermia and bacteriospermia and their impact on male fertility.

Polystyrene microplastics induce male reproductive toxicity in mice by activating spermatogonium mitochondrial oxidative stress and apoptosis

Microplastics have emerged as environmental hazards in recent years. This study was intended to prove the toxic effects of microplastics on the male reproductive system and further elucidate its mechanism. C57bl/6 mice were exposed to ultrapure water or different doses (0.25, 0.5 and 1 mg/d) of 5 μm polystyrene microplastics (PS-MPs) for 4 weeks, and the GC-1 mouse spermatogonium was treated with different concentrations of PS-MPs. The results showed that sperm count and motility were decreased, and sperm deformity rate was increased after exposure to PS-MPs. The morphology of testes in PS-MPs groups exhibited pathological changes, such as abnormal development of spermatogenic tubules, and inhibited spermatogonium function. Furthermore, the fluorescence intensity of TUNEL staining and the BAX/BCL2 ratio were increased. Exposure to PS-MPs resulted in impaired mitochondrial morphology of spermatogonium, decreased activity of GSH-px and SOD, and increased the MDA level. In vitro, after treatment with PS-MPs, the cell apoptosis rate of spermatogonium was significantly increased, mitochondrial membrane potential was decreased, mitochondrial morphology was damaged, and exposure to PS-MPs increased mitochondrial reactive oxygen species, inducing an oxidative stress state in spermatogonia. In summary, PS-MPs induced a decrease in sperm quality by activating spermatogonium mitochondrial oxidative stress and apoptosis, offering novel insights into mitigating the reproductive toxicity of microplastics.