Proteomics, oxidative stress and male infertility

Ellagic acid mitigates heat-induced testicular detriment in a mouse model

Heat stress has been shown to have a detrimental impact on testicular activity and spermatogenesis. Ellagic acid is a plant-derived organic compound that has a variety of biological functions. Thus, it is believed that ellagic acid may improve heat-stressed testicular dysfunction. There has been no research on the impact of ellagic acid on heat-stressed testicular dysfunction. The mice were divided into 4 groups. The first group was the normal control group (CN), and the second received heat stress (HS) by submerging the lower body for 15 min in a water bath with a thermostatically controlled temperature kept at 43°C (HS), and the third and fourth groups were subjected to heat-stress similar to group two and given two different dosages of ellagic acid (5 mg/kg (EH5) and 50 mg/kg (EH50) for 14 days. Ellagic acid at a dose of 50 mg/kg improved the level of circulating testosterone (increased 3βHSD) and decreases the oxidative stress. The testicular and epididymal architecture along with sperm parameters also showed improvement. Ellagic acid treatment significantly increases the germ cell proliferation (GCNA, BrdU staining) and Bcl2 expression and decreases active caspase 3 expression. Heat stress downregulated the expression of AR, ER-α and ER-β, and treatment with ellagic acid increased the expression of ER-α and ER-β markers in the 50 mg/kg treatment group. Thus, our finding suggests that ellagic acid ameliorates heat-induced testicular impairment through modulating testosterone synthesis, germ cell proliferation, and oxidative stress. These effects could be manifested by regulating androgen and estrogen receptors. However, the two doses showed differential effects of some parameters, which require further investigation.

Infertility: Focus on the therapeutic potential of extracellular vesicles

Infertility is a well-known problem that arises from a variety of reproductive diseases. Until now, researchers have tried various methods to restore fertility, including medication specific to the cause, hormone treatments, surgical removals, and assisted reproductive technologies. While these methods do produce results, they do not consistently lead to fertility restoration in every instance. The use of exosome therapy has significant potential in treating infertility in patients. This is because exosomes, microvesicles, and apoptotic bodies, which are different types of vesicles, play a crucial role in transferring bioactive molecules that aid in cell-to-cell communication. Reproductive fluids can transport a variety of molecular cargos, such as miRNAs, mRNAs, proteins, lipids, and DNA molecules. The percentage of these cargos in the fluids can be linked to their physiological and pathological status. EVs are involved in several physiological and pathological processes and offer interesting non-cellular therapeutic possibilities to treat infertility. EVs (extracellular vesicles) transplantation has been shown in many studies to be a key part of regenerating different parts of the reproductive system, including the production of oocytes and the start of sperm production. Nevertheless, the existing evidence necessitates testifying to the effectiveness of injecting EVs in resolving reproductive problems among humans. This review focuses on the current literature about infertility issues in both females and males, specifically examining the potential treatments involving extracellular vesicles (EVs).

Zinc and Its Impact on the Function of the Testicle and Epididymis

Zinc (Zn) is an essential trace element; it exhibits a plethora of physiological properties and biochemical functions. It plays a pivotal role in regulating the cell cycle, apoptosis, and DNA organization, as well as in protein, lipid, and carbohydrate metabolism. Among other important processes, Zn plays an essential role in reproductive health. The ZIP and ZnT proteins are responsible for the mobilization of Zn within the cell. Zn is an inert antioxidant through its interaction with a variety of proteins and enzymes to regulate the redox system, including metallothioneins (MTs), metalloenzymes, and gene regulatory proteins. The role of Zn in the reproductive system is of great importance; processes, such as spermatogenesis and sperm maturation that occur in the testicle and epididymis, respectively, depend on this element for their development and function. Zn modulates the synthesis of androgens, such as testosterone, for these reproductive processes, so Zn deficiency is related to alterations in sperm parameters that lead to male infertility.

Site-specific N-glycoproteomic analysis reveals up-regulated fucosylation in seminal plasma of asthenozoospermia

N-linked glycoproteins are rich in seminal plasma, playing essential roles in supporting sperm function and fertilization process. The alteration of seminal plasma glycans and its correspond glycoproteins may lead to sperm dysfunction and even infertility. In present study, an integrative analysis of glycoproteomic and proteomic was performed to investigate the changes of site-specific glycans and glycoptoteins in seminal plasma of asthenozoospermia. By large scale profiling and quantifying 5,018 intact N-glycopeptides in seminal plasma, we identified 92 intact N-glycopeptides from 34 glycoproteins changed in asthenozoospermia. Especially, fucosylated glycans containing lewis x, lewis y and core fucosylation were significantly up-regulated in asthenozoospermia compared to healthy donors. The up-regulation of fucosylated glycans in seminal plasma may interfere sperm surface compositions and regulation of immune response, which subsequently disrupts sperm function. Three differentiated expression of seminal vesicle-specific glycoproteins (fibronectin, seminogelin-2, and glycodelin) were also detected with fucosylation alteration in seminal plasma of asthenozoospermia. The interpretation of the altered site-specific glycan structures provides data for the diagnosis and etiology analysis of male infertility, as well as providing new insights into the potential therapeutic targets for male infertility.

Seminal plasma proteomics as putative biomarkers for male infertility diagnosis

Male infertility represents a significant global public health issue that is currently emerging as a prominent research focus. Presently, laboratories adhere to the guidelines outlined by the World Health Organization (WHO) manuals for conducting routine semen analysis to diagnose male infertility. However, the accuracy of results in predicting sperm quality and fertility is limited because some individuals with a normal semen analysis report, an unremarkable medical history, and a physical examination may still experience infertility. As a result, the importance of employing more advanced techniques to investigate sperm function and male fertility in the treatment of male infertility and/or subfertility becomes apparent. The standard test for evaluating human semen has been improved by more complex tests that look at things like reactive oxygen species (ROS) levels, total antioxidant capacity (TAC), sperm DNA fragmentation levels, DNA compaction, apoptosis, genetic testing, and the presence and location of anti-sperm antibodies. Recent discoveries of novel biomarkers have significantly enriched our understanding of male fertility. Moreover, the notable biological diversity among samples obtained from the same individual complicates the efficacy of routine semen analysis. Therefore, unraveling the molecular mechanisms involved in fertilization is pivotal in expanding our understanding of factors contributing to male infertility. By understanding how these proteins work and what role they play in sperm activity, we can look at the expression profile in men who can't have children to find diagnostic biomarkers. This review examines the various sperm and seminal plasma proteins associated with infertility, as well as proteins that are either deficient or exhibit aberrant expression, potentially contributing to male infertility causes.

Exogenous Oxidative Stress in Human Spermatozoa Induces Opening of the Mitochondrial Permeability Transition Pore: Effect on Mitochondrial Function, Sperm Motility and Induction of Cell Death

Oxidative stress (OS) and disrupted antioxidant defense mechanisms play a pivotal role in the etiology of male infertility. The alterations in reactive oxygen species (ROS) production and calcium (Ca2+) homeostasis are the main activators for the mitochondrial permeability transition pore (mPTP) opening. The mPTP opening is one of the main mechanisms involved in mitochondrial dysfunction in spermatozoa. This alteration in mitochondrial function adversely affects energy supply, sperm motility, and fertilizing capacity and contributes to the development of male infertility. In human spermatozoa, the mPTP opening has been associated with ionomycin-induced endogenous oxidative stress and peroxynitrite-induced nitrosative stress; however, the effect of exogenous oxidative stress on mPTP opening in sperm has not been evaluated. The aim of this study was to determine the effect of exogenous oxidative stress induced by hydrogen peroxide (H2O2) on mPTP opening, mitochondrial function, motility, and cell death markers in human spermatozoa. Human spermatozoa were incubated with 3 mmol/L of H2O2 for 60 min, and intracellular Ca2+ concentration, mPTP opening, mitochondrial membrane potential (ΔΨm), ATP levels, mitochondrial reactive oxygen species (mROS) production, phosphatidylserine (PS) externalization, DNA fragmentation, viability, and sperm motility were evaluated. H2O2-induced exogenous oxidative stress caused increased intracellular Ca2+, leading to subsequent mPTP opening and alteration of mitochondrial function, characterized by ΔΨm dissipation, decreased ATP levels, increased mROS production, and the subsequent alteration of sperm motility. Furthermore, H2O2-induced opening of mPTP was associated with the expression of apoptotic cell death markers including PS externalization and DNA fragmentation. These results highlight the role of exogenous oxidative stress in causing mitochondrial dysfunction, deterioration of sperm motility, and an increase in apoptotic cell death markers, including PS externalization and DNA fragmentation, through the mPTP opening. This study yielded new knowledge regarding the effects of this type of stress on mitochondrial function and specifically on mPTP opening, factors that can contribute to the development of male infertility, considering that the role of mPTP in mitochondrial dysfunction in human sperm is not completely elucidated. Therefore, these findings are relevant to understanding male infertility and may provide an in vitro model for further research aimed at improving human sperm quality.

Protective Effect of Low-Volume High-Intensity Interval Training on Aspirin-Induced Reproductive Impairments in Adult Male Wistar Rats

Lifestyle factors such as sedentary behavior and consumption of certain medications can disturb the function of the male reproductive system. In the present study, we investigated the potential co-treatment effects of low-volume high-intensity interval training (HIIT) on markers of reproductive function in adult male Wistar rats under aspirin (ASA) treatment. Eighteen adult male Wistar rats were randomized into three groups: control (C), aspirin treatment (AT), and aspirin treatment + exercise (ATE). Animals in the AT and ATE groups received an oral subchronic dose of aspirin (12.5 mg/kg body mass). The exercise was performed three times per week for 6 weeks (4-6 reps of 10-s sprints). Serum testosterone level, sperm parameters (sperm count, viability, maturity, and DNA fragmentation), histomorphometric (Leydig cell, tubule diameter, thickness of tubular epithelium, and indices of spermatogenesis and spermiogenesis), and histochemical parameter (testicular fat density) were assessed. Results revealed that compared to the C group, ASA consumption led to a negative alteration in serum testosterone levels, sperm parameters, and histomorphometric and histochemical parameters (P < 0.05). However, there were no significant differences between the C and ATE groups in terms of serum testosterone level, number of Leydig cells, epididymal fat density, tubule diameter, epithelium height, immature-to-mature sperm ratio, and DNA breakage (P > 0.05). These findings suggest that ASA treatment is associated with deleterious changes in male reproductive parameters. However, low-volume HIIT may prevent ASA-induced male reproductive impairments and could be considered a potential prophylactic measure in subjects under ASA treatment.

Application and discoveries of metabolomics and proteomics in the study of female infertility

Introduction

Female infertility is defined as the absence of clinical pregnancy after 12 months of regular unprotected sexual intercourse.

Methods

This study employed metabolomics and proteomics approaches to investigate the relationship between metabolites and proteins and female infertility. The study used metabolomics and proteomics data from the UK Biobank to identify metabolites and proteins linked to infertility.

Results

The results showed that GRAM domain-containing protein 1C and metabolites fibrinogen cleavage peptides ADpSGEGDFXAEGGGVR and 3-Hydroxybutyrate had a positive correlation with infertility, whereas proteins such as Interleukin-3 receptor subunit alpha, Thrombospondin type-1 domain-containing protein 1, Intestinal-type alkaline phosphatase, and platelet and endothelial cell adhesion molecule 1 exhibited a negative correlation. These findings provide new clues and targets for infertility diagnosis and treatment. However, further research is required to validate these results and gain a deeper understanding of the specific roles of these metabolites and proteins in infertility pathogenesis.

Discussion

In conclusion, metabolomics and proteomics techniques have significant application value in the study of infertility, allowing for a better understanding of the biological mechanisms underlying infertility and providing new insights and strategies for its diagnosis and treatment. These research findings provide a crucial biological mechanistic basis for early infertility screening, prevention, and treatment.

The role of seminal reactive oxygen species assessment in the setting of infertility and early pregnancy loss

The male contribution to a couple suffering with adverse early pregnancy outcomes is being increasingly investigated. Seminal oxidative stress is considered to cause sperm DNA damage, thus affecting the functional capacity of the sperm. Multiple lines of evidence support an association between elevated seminal reactive oxygen species (ROS) and infertility. In the setting of assisted reproduction various factors in the in vitro environment, differing from the in vivo environment, may exacerbate oxidative stress. Furthermore, seminal ROS levels have been found to be higher in the male partners of couple's affected by both spontaneous and recurrent pregnancy loss. There are several methods by which to assess ROS levels however they are costly, inconsistent and their incorporation into clinical practice is unclear. The value of ROS assessment lies in the ability to plan targeted therapies to improve pregnancy and live birth rates. As such, further robust study is required before firm conclusions can be made to inform clinical practice. We aim to review the available evidence regarding the role of seminal ROS in infertility and pregnancy loss.

State-of-the-art and future perspectives in infertility diagnosis: Conventional versus nanotechnology-based assays

According to the latest World Health Organization statistics, around 50 to 80 million people worldwide suffer from infertility, amongst which male factors are responsible for around 20 to 30 % of all infertility cases while 50 % were attributed to the female ones. As it is becoming a recurrent health problem worldwide, clinicians require more accurate methods for the improvement of both diagnosis and treatment schemes. By emphasizing the potential use of innovative methods for the rapid identification of the infertility causes, this review presents the news from this dynamic domain and highlights the benefits brought by emerging research fields. A systematic description of the standard techniques used in clinical protocols for diagnosing infertility in both genders is firstly provided, followed by the presentation of more accurate and comprehensive nanotechnology-related analysis methods such as nanoscopic-resolution imaging, biosensing approaches and assays that employ nanomaterials in their design. Consequently, the implementation of nanotechnology related tools in clinical practice, as recently demonstrated in the selection of spermatozoa, the detection of key proteins in the fertilization process or the testing of DNA integrity or the evaluation of oocyte quality, might confer excellent advantages both for improving the assessment of infertility, and for the success of the fertilization process.

Proteomic Analysis of Testicular Interstitial Fluid in Men with Azoospermia

Background

The primary microenvironment of the testis comprises testicular interstitial fluid (TIF) surrounding the seminiferous tubules and testicular interstitial tissue. The pathological alterations of germ and Sertoli cells could affect the TIF composition and might contain putative biomarkers for monitoring active spermatogenesis.

Objective

We identified differentially expressed proteins in the TIF of patients with obstructive (OA) or nonobstructive (NOA) azoospermia to elucidate the underlying etiology of defective spermatogenesis.

Design setting and participants

We prospectively enrolled nine patients, including three men with OA and six with NOA with (n = 3) and without (n = 3) successful sperm retrieval. Their TIF was collected during the testicular sperm extraction procedure.

Outcome measurements and statistical analysis

TIF was analyzed using liquid chromatography-tandem mass spectrometry to identify differentially expressed proteins specific to OA and NOA with or without successful sperm retrieval. The dysregulated protein was further validated using Western blotting.

Results and limitations

Among the 555 TIF proteins identified in NOA patients, 14 were downregulated relative to OA patients. These proteins participate in biological processes such as proteolysis, complement activation, and immune responses; complement and coagulation cascade pathways were also enriched. Furthermore, 68 proteins with significantly higher levels were identified in the TIF of NOA patients with successful sperm retrieval than in those with failed sperm retrieval; these are mainly implicated in oxidation-reduction processes. The expression of calreticulin, which can distinguish successful and failed testicular sperm retrieval in the NOA group, was validated by Western blotting.

Conclusions

We provide the first scientific evaluation of TIF protein composition in men with azoospermia. These findings will help identify the physiological and pathological roles of each protein in regulating sperm production. Thus, our study underscores the potential of TIF in sperm retrieval biomarker discovery and would serve as a foundation for further studies to improve treatment strategies against azoospermia.

Patient summary

Using a proteomic approach, we identified and analyzed the total protein content of testicular interstitial fluid in humans with defective spermatogenesis for the first time and discovered altered protein expression patterns in patients with nonobstructive azoospermia (NOA). Proteins related to oxidation-reduction processes were upregulated in NOA patients with successful sperm retrieval compared with those with failed sperm retrieval. This can aid the development of novel diagnostic tools for successful testicular sperm retrieval.

COVID-19 and Male Infertility: Is There a Role for Antioxidants?

Coronavirus disease 19 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), jeopardizes male fertility because of the vulnerability of the male reproductive system, especially the testes. This study evaluates the effects of the virus on testicular function and examines the potential role of antioxidants in mitigating the damage caused by oxidative stress (OS). A comprehensive PubMed search examined exocrine and endocrine testicular function alteration, the interplay between OS and COVID-19-induced defects, and the potential benefit of antioxidants. Although the virus is rarely directly detectable in sperm and testicular tissue, semen quality and hormonal balance are affected in patients, with some changes persisting throughout a spermatogenesis cycle. Testicular pathology in deceased patients shows defects in spermatogenesis, vascular changes, and inflammation. Acute primary hypogonadism is observed mainly in severely infected cases. Elevated OS and sperm DNA fragmentation markers suggest redox imbalance as a possible mechanism behind the fertility changes. COVID-19 vaccines appear to be safe for male fertility, but the efficacy of antioxidants to improve sperm quality after infection remains unproven due to limited research. Given the limited and inconclusive evidence, careful evaluation of men recovering from COVID-19 seeking fertility improvement is strongly recommended.

High doses of GrassOut Max poses reproductive hazard by affecting male reproductive function and early embryogenesis in Swiss albino mice

Clethodim is a widely used and approved class II herbicide, with little information about its impact on the reproductive system. Herein, we investigated the male reproductive toxicity of clethodim using a mouse model. GrassOut Max (26% clethodim-equivalent) or 50 mg kg^-1 body weight analytical grade clethodim (≥90%) were given orally to male mice for 10 d in varying doses. All parameters were assessed at 35 d from the first day of treatment. Significant decrease in testicular weight, decreased germ cell population, elevated DNA damage in testicular cells and lower serum testosterone level was observed post clethodim-equivalent exposure. Epididymal spermatozoa were characterized with significant decrease in motility, elevated DNA damage, abnormal morphology, chromatin immaturity and, decreased acetylated-lysine of sperm proteins. In the testicular cells of clethodim-equivalent treated mice, the expression of Erβ and Gper was significantly higher. Proteomic analysis revealed lower metabolic activity, poor sperm-oocyte binding potential and defective mitochondrial electron transport in spermatozoa of clethodim-equivalent treated mice. Further, fertilizing ability of spermatozoa was compromised and resulted in defective preimplantation embryo development. Together, our data suggest that clethodim exposure risks male reproductive function and early embryogenesis in Swiss albino mice via endocrine disrupting function.

Candidate genes and proteins regulating bull semen quality: a review

Poor semen profile reflected by suboptimum fertility statistics is a concern in bulls reared for breeding purpose. A critical review of research on candidate genes and proteins associated with semen quality traits will be useful to understand the progress of molecular marker development for bull semen quality traits. Here, we have tabulated and classified candidate genes and proteins associated with bull semen quality based on a literature survey. A total of 175 candidate genes are associated with semen quality traits in various breeds of cattle. Several studies using candidate gene approach have identified 26 genes carrying a total of 44 single nucleotide polymorphisms. Furthermore, nine genome-wide association studies (GWASes) have identified 150 candidate genes using bovine single nucleotide polymorphisms (SNP) chips. Three genes, namely membrane-associated ring-CH-type finger 1 (MARCH1), platelet-derived growth factor receptor beta, and phosphodiesterase type 1, were identified commonly in two GWASes, which, especially MARCH1, are required to explore their regulatory roles in bull semen quality in in-depth studies. With the advancement of high-throughput-omic technologies, more candidate genes associated with bull semen quality may be identified in the future. Therefore, the functional significance of candidate genes and proteins need to be delved further into future investigations to augment bull semen quality.

Apocynin Ameliorates Monosodium Glutamate Induced Testis Damage by Impaired Blood-Testis Barrier and Oxidative Stress Parameters

BACKGROUND

the aim of this study was to investigate the effects of apocynin (APO) on hormone levels, the blood-testis barrier, and oxidative biomarkers in monosodium glutamate (MSG) induced testicular degeneration.

METHODS

Sprague Dawley male rats (150-200 g; n = 32) were randomly distributed into four groups: control, APO, MSG, and MSG + APO. MSG and MSG + APO groups were administered MSG (120 mg/kg) for 28 days. Moreover, the APO and MSG + APO groups received APO (25 mg/kg) during the last five days of the experiment. All administrations were via oral gavage. Finally, biochemical analyses were performed based on the determination of testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD), as well as light and transmission electron microscopic examinations, assessment of sperm parameters, ZO-1, occludin, NOX-2, and TUNEL immunohistochemistry were evaluated.

RESULTS

MSG increased both the oxidative stress level and apoptosis, decreased cell proliferation, and caused degeneration in testis morphology including in the blood-testis barrier. Administration of apocynin reversed all the deteriorated morphological and biochemical parameters in the MSG + APO group.

CONCLUSIONS

apocynin is considered to prevent testicular degeneration by maintaining the integrity of the blood-testis barrier with balanced hormone and oxidant/antioxidant levels.

The Role of Seminal Oxidative Stress in Recurrent Pregnancy Loss

Recurrent pregnancy loss is a distressing condition affecting 1–2% of couples. Traditionally investigations have focused on the female, however more recently researchers have started to explore the potential contribution of the male partner. Seminal reactive oxygen species have a physiological function in male reproduction but in excess are suspected to generate structural and functional damage to the sperm. Evidence is mounting to support an association between elevated seminal reaction oxygen species and recurrent pregnancy loss. Studies suggest that the rates of sperm DNA damage are higher in the male partners of women affected by recurrent pregnancy loss compared with unaffected men. However, the available pool of data is conflicting, and interpretation is limited by the recent change in nomenclature and the heterogeneity of study methodologies. Furthermore, investigation into the effects of oxidative stress on the epigenome show promise. The value of antioxidant therapy in the management of recurrent pregnancy loss currently remains unclear.

Effects of zinc chloride on boar sperm quality during liquid storage at 17°C

OBJECTIVES

The aim of this study was to evaluate the effects of zinc chloride (ZnCl₂ ) at 20, 50, 100, and 200 μg/mL on the quality of seminal plasma-free boar sperm stored at 17°C for 7 days and to explore the underlying mechanisms.

METHODS

Boar sperm were collected and incubated in non-capacitation/capacitation medium to analyze sperm quality.

RESULTS

In the non-capacitated state, the addition of ZnCl₂ at 20 and 50 μg/mL improved the survival rate and plasma membrane integrity of boar sperm (p < 0.05). Compared to the control group, the addition of ZnCl₂ significantly increased total antioxidative capacity and CuZn superoxide dismutase activity, while reducing the malondialdehyde content (p < 0.05). ZnCl₂ at 100 and 200 μg/mL significantly decreased sperm motility, protein kinase A (PKA) substrate phosphorylation, and tyrosine phosphorylation. These proteins were mainly located on the mid-pieces of the flagellum. The addition of ZnCl₂ at 20 and 50 μg/mL conveyed a protective effect to boar sperm stored at 17°C. Furthermore, ZnCl₂ at 100 and 200 μg/mL inhibited sperm motility via tyrosine phosphorylation, thus preventing the 'capacitation-like' state. In the capacitated state, there was no change in PKA substrate phosphorylation and tyrosine phosphorylation of the mid-pieces of the flagellum compared to the control groups, indicating that the addition of Zn²⁺ did not negatively affect capacitation of preserved sperm.

CONCLUSIONS

ZnCl₂ showed protective capacity to the preservation extender used for boar sperm during the process of 17°C storage, and the optimal concentration of ZnCl₂ for the preservation extender was 100 μg/mL.

Heat stress disrupts spermatogenesis via modulation of sperm-specific calcium channels in rats

Heat is a detrimental environmental stressor that disrupts spermatogenesis and results in male infertility. Previous investigations have shown that heat stress reduces the motility, number, and fertilization ability of living spermatozoa. Sperm hyperactivation, capacitation, acrosomal reaction, and chemotaxis towards the ova are regulated by the cation channel of sperm (CatSper). This sperm-specific ion channel triggers the influx of calcium ions into sperm cells. The aim of this study in rats was to investigate whether heat treatment affected the expression levels of CatSper-1 and -2, together with the sperm parameters, testicular histology and weight. The rats were exposed to heat stress for 6 days and the cauda epididymis and testis were collected 1, 14, and 35 days after heat treatment to measure sperm parameters, gene and protein expression, testicular weight, and histology. Interestingly, we found that heat treatment caused a notable downregulation of CatSper-1 and -2 expression at all three time points. In addition, there were significant reductions in sperm motility and number and an increase in the percentage of abnormal sperm at 1 and 14 days, with cessation of sperm production at 35 days. Furthermore, expression of the steroidogenesis regulator, 3 beta-hydroxysteroid dehydrogenase (3β-HSD) was upregulated in the 1-, 14- and 35-day samples. Heat treatment also upregulated the expression of the apoptosis regulator, BCL2-associated X protein (BAX), decreased testicular weight, and altered testicular histology. Therefore, our data showed for the first time that heat stress downregulated CatSper-1 and -2 in the rat testis, and that this may be a mechanism involved in heat stress-induced impairment of spermatogenesis.

Unraveling the harmful effect of oxidative stress on male fertility: A mechanistic insight

Male infertility is a widely debated issue that affects males globally. There are several mechanisms involved. Oxidative stress is accepted to be the main contributing factor, with sperm quality and quantity affected by the overproduction of free radicals. Excess reactive oxygen species (ROS) cannot be controlled by the antioxidant system and, thus, potentially impact male fertility and hamper sperm quality parameters. Mitochondria are the driving force of sperm motility; irregularities in their function may lead to apoptosis, alterations to signaling pathway function, and, ultimately, compromised fertility. Moreover, it has been observed that the prevalence of inflammation may arrest sperm function and the production of cytokines triggered by the overproduction of ROS. Further, oxidative stress interacts with seminal plasma proteomes that influence male fertility. Enhanced ROS production disturbs the cellular constituents, particularly DNA, and sperms are unable to impregnate the ovum. Here, we review the latest information to better understand the relationship between oxidative stress and male infertility, the role of mitochondria, the cellular response, inflammation and fertility, and the interaction of seminal plasma proteomes with oxidative stress, as well as highlight the influence of oxidative stress on hormones; collectively, all of these factors are assumed to be important for the regulation of male infertility. This article may help improve our understanding of male infertility and the strategies to prevent it.

Influence of Fruit and Vegetable Consumption on Antioxidant Status and Semen Quality: A Cross-Sectional Study in Adult Men

The influence of fruit and vegetable consumption on semen quality by reducing oxidative stress is inconsistent. Thus, the association between the consumption of these products, antioxidant status, and semen quality was investigated in 90 men aged 18–40. The consumption of fruit and vegetables was collected using the 3-day food record method. Antioxidant status: total antioxidant capacity in semen (TAC-s) and blood (TAC-b), blood superoxide dismutase (SOD-b), glutathione reductase (GR-b), glutathione peroxidase (GPx-b), catalase (CAT-b) activity, and malondialdehyde concentration in blood (MDA-b) were measured. Sperm concentration, leukocytes in the ejaculate, vitality, motility, and sperm morphology were examined using computer-aided semen analysis (CASA). The consumption of fruit and vegetables was positively correlated with sperm concentration, vitality, motility, TAC-s, TAC-b, and SOD-b activity. The TAC-s and TAC-b were positively related to motility, TAC-s was inversely correlated with sperm tail defects. The SOD-b activity was positively correlated with vitality, motility, sperm morphology, and inversely with sperm tail defects and leukocytes in the ejaculate. Compared to the men in the first quartile of fruit and vegetable consumption (<318 g/day), those in the highest quartile (>734 g/day) had the highest sperm concentration, vitality, motility, TAC-s, TAC-b, GPx-b activity, and the lowest MDA-b concentration (based on multivariate regression models). A high consumption of fruit and vegetables may positively influence selected sperm quality parameters by improving the antioxidant status of semen and blood.

Highly Cited Articles in the Field of Male Infertility and Antioxidants: A Scientometric Analysis

PURPOSE

The objective of this scientometric analysis was to recognize the top 100 cited articles on 'Male infertility and Antioxidants' and analyze its publication characteristics.

MATERIALS AND METHODS

The Scopus database was used to retrieve related articles and the top 100 identified based on citation rate.

RESULTS

The articles were published in 56 journals between 1995 and 2019 with a median (interquartile range) citation score of 17 (5-62). Among the top 100 articles, 69 were clinical studies, which included controlled and blinded (33.33%), prospective (27.54%), randomized-controlled trials (26.09%), uncontrolled (11.59%), and retrospective (1.45%) studies. In addition to conventional semen parameters, advanced sperm function tests such as oxidative stress (51%) and sperm DNA damage (23%) were reported. Pregnancy rate (33%) was found to be the most reported reproductive outcome. Antioxidant therapy was mostly investigated in male cohorts with sperm abnormalities such as asthenozoospermia (28%) and clinical conditions such as idiopathic male infertility (20%), varicocele/varicocelectomy (17%) and general male infertility (16%).

CONCLUSIONS

The most influential publications on antioxidants and male infertility were identified for the first time in the literature. This will serve as a reliable source of information for researchers and clinicians alike.

Antioxidant enzymes and association of CAT SNP-21 A/T (rs7943316) with male infertility

Infertility is a multifactorial and polygenic disease. A vast majority of infertility is still unexplained despite modern diagnostic techniques. Oxidative stress is considered a factor for male infertility but etiology in terms of functional gene polymorphism and experimental studies on human subjects is scarcely reported. The aim of the study was to investigate the status of three antioxidant enzymes; catalase, superoxide dismutase (SOD), and glutathione reduced (GSH) in clinically diagnosed infertile males and find the potential association of CAT gene variant in the promoter region -21 A/T (rs7943316). The study consisted of 55 clinically diagnosed infertile males and 50 non-infertile volunteers. The activity of antioxidant enzymes was measured through a spectrophotometer. Polymerase chain reaction-restriction fragment length polymorphism was performed for genotyping of single-nucleotide polymorphism. Catalase enzyme activity was significantly decreased while SOD and GSH were substantially increased (p ≤ 0.01) in infertile men in comparison to non-infertile. CAT gene variant rs7943316 had shown significant association in dominant, recessive model and allelic frequencies. The study concludes that rs7943316 has a substantial role in male infertility. The outcome of the study may help in resolving idiopathic infertility cases and may help in evolving novel diagnostic and therapeutic approaches. Other variants of CAT and antioxidant genes are suggested to ascertain further insight.

iTRAQ-based proteomic analysis of sperm reveals candidate proteins that affect the quality of spermatozoa from boars on plateaus

Background

Tibetan pigs (TP) exhibit heritable adaptations to their hypoxic environments as a result of natural selection. However, candidate proteins that affect the sperm quality of boars on plateaus have not yet been clearly investigated.

Methods

In this study, to reveal the candidate proteins that affect the quality of spermatozoa of boars on plateaus, we analyzed the sperm quality using computer-assisted semen analysis (CASA) system and reactive oxygen species (ROS) levels. We also compared the proteomes of sperm proteomes between TP and Yorkshire pigs (YP) raised at high altitudes using the isobaric tags for relative and absolute quantitation (iTRAQ) in combination with the liquid chromatography-tandem mass spectrometry (LC–MS/MS) proteomic method, and confirmed the relative expression levels of the four proteins by western blotting.

Results

The sperm quality of the TP was superior to that of the YP on plateaus. Of the 1,555 quantified proteins, 318 differentially expressed proteins (DEPs) were identified. Gene ontology (GO) analysis revealed that the DEPs were predominantly associated with the sorbitol metabolic process, removal of superoxide radicals, cellular response to superoxide, response to superoxide and regulation of the mitotic spindle assembly. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were mainly enriched in pathways involved in the regulation of the actin cytoskeleton, glutathione metabolism, oxidative phosphorylation, and estrogen signaling. Based on the protein–protein interaction (PPI) network analysis, we identified 8 candidate proteins (FN1, EGF, HSP90B1, CFL1, GPX4, NDUFA6, VDAC2, and CP) that might play important roles and affect the sperm quality of boars on plateaus. Moreover, the relative expression levels of four proteins (CFL1, EGF, FN1, and GPX4) were confirmed by western blot analysis.

Conclusions

Our study revealed 8 candidate proteins (FN1, EGF, HSP90B1, CFL1, GPX4, NDUFA6, VDAC2, and CP) that affect the sperm quality of boar on plateaus and provide a reference for further studies on improving sperm quality and the molecular breeding of boars on plateaus.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12953-021-00177-9.

Effects of exposure to methylglyoxal on sperm motility and embryonic development after fertilization in mice

Methylglyoxal (MG) is a precursor for the generation of endogenous advanced glycation end-products involved in various diseases, including infertility. The present study evaluated the motility and developmental competence after in vitro fertilization of mouse sperm which were exposed to MG in the capacitation medium for 1.5 h. Sperm motility was analyzed using an SQA-V automated sperm quality analyzer. Intracellular reactive oxygen species (ROS), membrane integrity, mitochondrial membrane potential, and DNA damage were assessed using flow cytometry. The matured oocytes were inseminated with MG-exposed sperm, and subsequently, the fertilization and embryonic development in vitro were evaluated in vitro. The exposure of sperm to MG did not considerably affect the swim-up of sperm but resulted in a deteriorated sperm motility in a concentration-dependent manner, which was associated with a decreased mitochondrial activity. However, these effects was not accompanied by obvious ROS accumulation or DNA damage. Furthermore, MG diminished the fertilization rate and developmental competence, even after normal fertilization. Collectively, a short-term exposure to MG during sperm capacitation had a critical impact on sperm motility and subsequent embryonic development after fertilization. Considering that sperm would remain in vivo for up to 3 days until fertilization, our findings suggest that sperm can be affected by MG in the female reproductive organs, which may be associated with infertility.

The effect of iron and/or zinc diet supplementation and termination of this practice on the antioxidant status of the reproductive tissues and sperm viability in rats

AIMS

The aim of this study was to investigate the effect of iron or/and zinc supplementation and termination of this treatment on the antioxidant defence of the male reproductive system and sperm viability in rats.

METHODS

The study consisted of 3 stages: I) 4-week adaptation to the diets (C-control or D-iron deficient); II) 4-week iron and/or zinc supplementation (10-times more than in the C diet of iron: CSFe, DSFe; zinc: CSZn, DSZn; or iron and zinc: CSFeZn, DSFeZn; and III) 2-week post-supplementation period (the same diets as during stage I). Parameters of antioxidant status (total antioxidant capacity and SOD, GPx, and CAT activiy), oxidative damage (lipid and protein peroxidation), and sperm viability were measured.

RESULTS

Simultaneous iron and zinc supplementation compared to iron supplementation (CSFeZn vs CSFe) increased SOD activity in the testes and decreased the level of malondialdehyde in the epididymis after stage II, and increased the percentage of live sperm after stage III. After discontinuation of the iron and zinc supplementation and a return to the control diet, the following was observed a decrease of SOD activity in the testes and GPx activity in the epididymis, and a increase malondialdehyde concentration in prostates. After stage III, in DSFeZn vs DSFe rats, an increase of SOD and CAT activity in the epididymis was found.

CONCLUSION

Zinc supplementation simultaneous with iron may protect the male reproductive system against oxidative damage induced by high doses of iron and may have a beneficial effect on sperm viability. The effect of this supplementation was observed even two weeks after the termination of the intervention.

Role of Zinc (Zn) in Human Reproduction: A Journey from Initial Spermatogenesis to Childbirth

Zinc (Zn), the second-most necessary trace element, is abundant in the human body. The human body lacks the capacity to store Zn; hence, the dietary intake of Zn is essential for various functions and metabolism. The uptake of Zn during its transport through the body is important for proper development of the three major accessory sex glands: the testis, epididymis, and prostate. It plays key roles in the initial stages of germ cell development and spermatogenesis, sperm cell development and maturation, ejaculation, liquefaction, the binding of spermatozoa and prostasomes, capacitation, and fertilization. The prostate releases more Zn into the seminal plasma during ejaculation, and it plays a significant role in sperm release and motility. During the maternal, labor, perinatal, and neonatal periods, the part of Zn is vital. The average dietary intake of Zn is in the range of 8-12 mg/day in developing countries during the maternal period. Globally, the dietary intake of Zn varies for pregnant and lactating mothers, but the average Zn intake is in the range of 9.6-11.2 mg/day. The absence of Zn and the consequences of this have been discussed using critical evidence. The events and functions of Zn related to successful fertilization have been summarized in detail. Briefly, our current review emphasizes the role of Zn at each stage of human reproduction, from the spermatogenesis process to childbirth. The role of Zn and its supplementation in in vitro fertilization (IVF) opens opportunities for future studies on reproductive biology.

Male infertility

It is estimated that infertility affects 8-12% of couples globally, with a male factor being a primary or contributing cause in approximately 50% of couples. Causes of male subfertility vary highly, but can be related to congenital, acquired, or idiopathic factors that impair spermatogenesis. Many health conditions can affect male fertility, which underscores the need for a thorough evaluation of patients to identify treatable or reversible lifestyle factors or medical conditions. Although semen analysis remains the cornerstone for evaluating male infertility, advanced diagnostic tests to investigate sperm quality and function have been developed to improve diagnosis and management. The use of assisted reproductive techniques has also substantially improved the ability of couples with infertility to have biological children. This Seminar aims to provide a comprehensive overview of the assessment and management of men with infertility, along with current controversies and future endeavours.

Differential proteome between ejaculate and epididymal sperm represents a key factor for sperm freezability in wild small ruminants

Epididymal sperm shows higher cryoresistance than ejaculated sperm. Although the sperm proteome seems to affect cell cryoresistance, studies aiming at identifying proteins involved in sperm freezing-tolerance are scarce. The aims of this study were to investigate differences of sperm freezability and proteome between epididymal and ejaculated sperm in three mountain ungulates: Iberian ibex, Mouflon and Chamois. Sperm samples were cryopreserved in straws by slow freezing. Tandem mass tag-labeled peptides from sperm samples were analyzed by high performance liquid chromatography coupled to a mass spectrometer in three technical replicates. The statistical analysis was done using the moderated t-test of the R package limma. Differences of freezability between both types of sperm were associated with differences of the proteome. Overall, epididymal sperm showed higher freezability than ejaculated sperm. Between 1490 and 1883 proteins were quantified in each species and type of sperm sample. Cross species comparisons revealed a total of 76 proteins that were more abundant in epididymal than in ejaculated sperm in the three species of study whereas 3 proteins were more abundant in ejaculated than epididymal sperm in the three species of study (adjusted P < 0.05; |log₂| fold-change > 0.5). Many of the proteins that were associated with higher cryoresistance are involved in stress response and redox homeostasis. In conclusion, marked changes of sperm proteome were detected between epididymal and ejaculated sperm. This work contributes to update the sperm proteome of small ruminants and to identify candidate markers of sperm freezability.

Differential seminal plasma proteome signatures of boars with high and low resistance to hypothermic semen preservation at 5°C

BACKGROUND

Hypothermic storage at 5°C has been investigated as an alternative to promote the prudent use of antibiotics for boar artificial insemination doses. However, this temperature is challenging for some ejaculates or boars.

OBJECTIVE

The present study aimed to identify putative biomarkers for semen resistance to hypothermic storage at 5°C by comparing the seminal plasma proteomes of boars with high and low seminal resistance to preservation at 5°C.

MATERIALS AND METHODS

From an initial group of 34 boars, 15 were selected based on the following criteria: ejaculate with ≤20% abnormal spermatozoa and at least 70% progressive motility at 120 hours of storage at 17°C. Then, based on the response to semen hypothermic storage at 5°C, boars were classified into two categories: high resistance-progressive motility of >75% in the three collections (n = 3); and low resistance-progressive motility of <75% in the three collections (n = 3). Seminal plasma proteins were analyzed in pools, and differential proteomics was performed using Multidimensional Protein Identification Technology.

RESULTS

Progressive motility was lower at 120 hours of storage in low resistance, compared to high resistance boars (P < .05). Acrosome and plasma membrane integrity were not affected by the boar category, storage time, or their interaction (P ≥ .104). Sixty-five proteins were considered for differential proteomics. Among the differentially expressed and exclusive proteins, the identification of proteins such cathepsin B, legumain, and cystatin B suggests significant changes in key enzymes (eg, metalloproteinases) involved in spermatogenesis, sperm integrity, and fertilizing potential.

DISCUSSION AND CONCLUSION

Differences in the seminal plasma suggest that proteins involved in the proteolytic activation of metalloproteinases and proteins related to immune response modulation could disrupt key cellular pathways during spermatogenesis and epididymal maturation, resulting in altered resistance to chilling injury. Further in vivo studies focusing on the immunological crosstalk between epithelial cells and gametes might explain how the immune regulators influence sperm resistance to hipothermic storage.

Oxidative stress and male infertility

BACKGROUND

Between 30% and 80% of patients with male infertility produce excessive reactive oxygen species (ROS) in their ejaculate even though the cause of male infertility is unexplained in approximately half of cases. The strong connection between oxidative stress (OS) and male infertility has led recent investigators to propose the term "Male Oxidative Stress Infertility (MOSI)" to describe OS-associated male infertility.

METHODS

We searched the PubMed database for original and review articles to survey the effects of OS on male infertility, and then verified the effects and treatments.

MAIN FINDINGS

Seminal plasma contains many antioxidants that protect sperm from ROS, because low amounts of ROS are required in the physiological fertilization process. The production of excessive ROS causes OS which can lower fertility through lipid peroxidation, sperm DNA damage, and apoptosis. Several assays are available for evaluating OS, including the MiOXSYS® analyzer to measure oxidation-reduction potential. Several measures should be considered for minimizing OS and improving clinical outcomes.

CONCLUSION

Accurately diagnosing patients with MOSI and identifying highly sensitive biomarkers through proteomics technology is vital for better clinical outcomes.

Overtime expression of plasma membrane and mitochondrial function markers associated with cell death in human spermatozoa exposed to nonphysiological levels of reactive oxygen species

In many cell types, the potential of reactive oxygen species to induce death processes has been largely demonstrated. Studies in spermatozoa have associated the imbalance of reactive oxygen species and phosphatidylserine externalisation as an apoptosis marker. However, the lack of consensus about time effect in the joint expression of these and other death markers has made it difficult to understand the set of mechanisms influenced beyond the concentration effect of reactive oxygen species to stimulate cell death. Here, the plasma membrane permeability and integrity, phosphatidylserine externalisation and mitochondrial membrane potential were jointly evaluated as death markers in human spermatozoa stimulated with H₂ O₂ . The results showed a profound and sustained effect of dissipation in the mitochondrial membrane potential and an increased phosphatidylserine externalisation in human spermatozoa exposed to 3 mmol^-1 of H₂ O₂ at 30 min. This was followed by an increased membrane permeability after 45 min. The last observed event was the loss of cell membrane integrity at 60 min. In conclusion, mitochondria are rapidly affected in human spermatozoa exposed to reactive oxygen species, with the barely detectable mitochondrial membrane potential coexisting with the high phosphatidylserine externalisation in cells with normal membrane permeability.

Seminal Plasma Proteomic Biomarkers of Oxidative Stress

The prevalence of idiopathic male infertility is high, up to 75% of patients with abnormal sperm parameters. Hence, the research of its causes is mandatory. Oxidative stress (OS) can be responsible for male infertility in 30–80% of cases. In recent years, seminal plasma (SP) proteomics has developed as a useful tool to provide biomarkers of specific diseases. This systematic review aims to collect the available evidence on the changes of SP proteome in patients exposed to OS to provide possible SP biomarkers of sperm OS. To accomplish this, the following keyterms “seminal fluid proteome”, “seminal plasma proteome”, “oxidative stress”, and “sperm oxidative stress” were used and 137 records were found. Among these, 17 were finally included. Nine proteins involved with OS were found overexpressed in patients with OS. Twenty-three proteins were found differentially expressed in patients with clinical conditions associated with OS, such as varicocele, male accessory gland infection/inflammation, cigarette smoke, and obesity. These proteins do not seem to overlap among the clinical conditions taken into account. We speculate that specific SP proteins may mediate OS in different clinical conditions. Altogether, these results suggest that proteomics could help to better understand some of the molecular mechanisms involved in the pathogenesis of infertility. However, further studies are needed to identify potential biomarkers of male infertility with valuable clinical significance.

In vivo and in silico evaluation of the ameliorative effect of hesperidin on finasteride-induced testicular oxidative stress in Wistar rats

Finasteride used for treating benign prostatic hyperplasia is associated with undesirable side effects via oxidative stress related mechanisms. This study employed in vivo and in silico methods to investigate the protective role of hesperidin against testicular toxicity induced by finasteride and the possible molecular mechanisms involved. Male Wistar rats were randomized into four groups of six animals each. Group I (control) were administered distilled water, group II received finasteride (3.1 mg/kg bw), group III received hesperidin (100 mg/kg bw), while group IV were co-administered finasteride and hesperidin. Administration was by gavage for 14 days. The binding propensities of finasteride and hesperidin for 5α-reductase were assessed using in silico docking approach. Finasteride administration caused significant reductions of sperm motility, volume, count, and live/dead ratio, with significant increase in numbers of abnormal sperms. Finasteride treatment also resulted in diminished activities of superoxide dismutase, catalase and glutathione-S-transferase, significant reduction in the concentration of reduced glutathione and ascorbic acid, and increased testicular malondialdehyde level relative to control. Moreover, significant increase in the activities of testicular lactate dehydrogenase and γ-glutamyl transferase was observed, with significant decrease in the activities of acid phosphatase and alkaline phosphatase relative to finasteride-treated rats. Furthermore, hesperidin exhibited favorable binding affinity for 5α -reductase (5AR) in silico compared to finasteride. Co-administration with hesperidin ameliorated finasteride-induced testicular damage by suppressing oxidative stress indices, enhancing antioxidant status, improving sperm parameters and alterations in the activities of marker enzymes, as well as possibly inhibiting the binding of finasteride to 5AR.

Exosome Composition and Seminal Plasma Proteome: A Promising Source of Biomarkers of Male Infertility

Infertility has become a global health issue, with approximately 50% of infertility cases generated by disorders in male reproduction. Spermatozoa are conveyed towards female genital tracts in a safe surrounding provided by the seminal plasma. Interestingly, this dynamically changing medium is a rich source of proteins, essential not only for sperm transport, but also for its protection and maturation. Most of the seminal proteins are acquired by spermatozoa in transit through exosomes (epididymosomes and prostasomes). The high number of seminal proteins, the increasing knowledge of their origins and biological functions and their differential expression in the case of azoospermia, asthenozoospermia, oligozoospermia and teratozoospermia or other conditions of male infertility have allowed the identification of a wide variety of biomarker candidates and their involvement in biological pathways, thus to strongly suggest that the proteomic landscape of seminal plasma may be a potential indicator of sperm dysfunction. This review summarizes the current knowledge in seminal plasma proteomics and its potentiality as a diagnostic tool in different degrees of male infertility.

Protein signatures of seminal plasma from bulls with contrasting frozen-thawed sperm viability

The present study investigated the seminal plasma proteome of Holstein bulls with low (LF; n = 6) and high (HF; n = 8) sperm freezability. The percentage of viable frozen-thawed sperm (%ViableSperm) determined by flow cytometry varied from -2.2 in LF to + 7.8 in HF bulls, as compared to the average %ViableSperm (54.7%) measured in an 860-sire population. Seminal proteins were analyzed by label free mass spectrometry, with the support of statistical and bioinformatics analyses. This approach identified 1,445 proteins, associated with protein folding, cell-cell adhesion, NADH dehydrogenase activity, ATP-binding, proteasome complex, among other processes. There were 338 seminal proteins differentially expressed (p < 0.05) in LF and HF bulls. Based on multivariate analysis, BSP5 and seminal ribonuclease defined the HF phenotype, while spermadhesin-1, gelsolin, tubulins, glyceraldehyde-3-phosphate dehydrogenase, calmodulin, ATP synthase, sperm equatorial segment protein 1, peroxiredoxin-5, secretoglobin family 1D and glucose-6-phosphate isomerase characterized the LF phenotype. Regression models indicated that %ViableSperm of bulls was related to seminal plasma peroxiredoxin-5, spermadhesin-1 and the spermadhesin-1 × BSP5 interaction (R2 = 0.84 and 0.79; p < 0.05). This report is the largest dataset of bovine seminal plasma proteins. Specific proteins of the non-cellular microenvironment of semen are potential markers of sperm cryotolerance.

Proteomic analysis of seminal plasma from bilateral varicocele patients indicates an oxidative state and increased inflammatory response

Seminal plasma is a rich source of proteins and serves as an ideal sample for proteomic analysis of male infertility. In varicocele-associated infertility, the contributory role of seminal plasma proteins specific to unilateral and bilateral varicocele is not clear. Furthermore, there is a lack of specific protein biomarker to differentiate bilateral from unilateral varicocele. The main objective is to identify the differentially regulated molecular and cellular pathways in bilateral varicocele. Furthermore, we intend to identify seminal plasma biomarkers to differentiate bilateral and unilateral varicocele patients in comparison with fertile healthy men. Global proteomic analysis of seminal plasma proteins has identified the functionality of differentially expressed proteins (DEPs) in varicocele patients. Bioinformatic analysis has revealed response to reactive oxygen species and oxidative stress, and tissue homeostasis as top process pathways that are affected in bilateral varicocele patients compared to fertile healthy men. In comparison with unilateral varicocele patients, inflammatory response pathways were dysregulated, especially interleukin 6 (IL-6) signaling and Janus kinase-signal transducer and activator of transcription (Jak-STAT) pathways, in bilateral varicocele patients, owing to the involvement of underexpressed DEPs. Key DEPs associated with oxidative stress (peroxiredoxin 2; PRDX2), DNA fragmentation (fatty acid synthase; FASN), and inflammatory response (fibronectin 1; FN1) validated by western blot analysis revealed differential expression of these proteins in unilateral and bilateral varicocele groups. Altered expression of DEPs and its association with key processes show that the seminal plasma homeostasis is compromised in bilateral varicocele patients. Furthermore, we propose PRDX2, FASN, and FN1 as potential noninvasive seminal plasma markers for the differentiation of unilateral and bilateral varicocele patients.

Antioxidant potential of seminal plasma in normozoospermia and asthenozoospermia

The study objective is to evaluate the antioxidant potential of seminal plasma in normozoospermia and asthenozoospermia.

Materials and methods. Samples of ejaculate from 57 men of reproductive age were studied. Standard spermiologic examination and determination of the antioxidant potential of the seminal fluid using an original chemiluminescent method were performed. The method allowed to measure duration of the latent period from the moment of a decrease in luminescence of the solution containing reactive oxygen species (ROS) after addition of the seminal fluid until the most dramatic increase in luminescence corresponding to decreased antioxidant effect of the seminal fluid.

Results. In the samples, the latent time varies from 4.6 to 17.5 minutes. Compared with normozoospermia, the antioxidant potential is significantly lower (p = 0.05) in men with asthenozoospermia (about 1.4 times), and even lower in patients with asthenoteratozoospermia (about 1.7 times) (p = 0.03). An inverse weak correlation was found between the activity of leukocytes and latent time in pathospermia (r = –0.23 and –0.18 for asthenozoospermia и asthenoteratozoospermia, respectively). A direct strong correlation was found between ROS-producing sperm activity and latent time in normozoospermia (p = 0.79), and inverse correlation in pathospermia (r = –0.26 and –0.62 for asthenozoospermia и asthenoteratozoospermia, respectively).

Conclusion. Pathospermia is characterized by antioxidant seminal plasma deficiency, more pronounced for asthenoteratozoospermia. The antioxidant system of seminal plasma correlates with the ROS-producing ability of leukocytes and, to a greater extent, of the sperm.

 With normozoospermia, the oxidative balance is maintained, with pathospermia, a higher value of ROS production by sperm corresponds to a lower value of antioxidant capacity.

Impact of thermal stress exposure on seminal quality, antioxidant defence system, TNF-α and TIMP-3 in Ossimi ram

Heat stress (HS) occupies huge importance nowadays as it leads to severe economic losses especially in livestock. Preserving sheep against HS is one of the governmental scopes where it represents huge percentage of global ruminant. The present research was conducted to study semen quality, some stress and inflammatory markers in Ossimi rams under both hot and mild climatic conditions. The current study was conducted on selected 46 ram samples divided into two groups during summer and winter. Semen analysis, testosterone (TES), cortisol (COR) and blood glucose (BG) levels, and lipid and protein profiles were done. Concentrations of tumour necrosis factor alpha (TNF-α), tissue inhibitor of metalloproteinase-3 (TIMP-3), nitric oxide (NO), malondialdehyde (MDA) and reduced glutathione (GSH) and specific activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD) were assessed. The results in summer compared to winter revealed significant elevation of total defects and number of dead sperms; however, there was reduction in sperm total motility and concentration and external epididymal tail duct diameter. Histological study of epididymal tail lumen exhibited azoospermia. Further, TES, TIMP-3 and GSH levels were decreased and COR, TNF-α, NO and MDA were raised. Specific activities of GPx and SOD were also declined. Additionally, there was a significant increase in concentrations of BG and lipid profiles except high-density lipoprotein. Our data concluded that there were new insights into TNF-α and TIMP-3 as biomarkers can be used in diagnosis of sheep suffering from HS, but further studies are recommended to do in future work about such aspect.

Protein profiling in unlocking the basis of varicocele-associated infertility

Varicocele is one of the major causes of male infertility and has a negative impact on spermatogenesis. The conventional semen analysis does not reveal the underlying subcellular mechanisms associated with defects in spermatozoa. Proteomics and bioinformatics analysis can be used to identify the molecular aetiologies associated with poor semen quality in varicocele patients. Mitochondrial dysfunction has been identified as the main factor affecting normal physiological functions of spermatozoa. This article discusses the proteomic studies of spermatozoa and seminal plasma in varicocele patients. Proteomics can identify potential spermatozoa and seminal plasma biomarkers in varicocele-mediated male infertility. In future, these protein biomarkers can be useful in the development of noninvasive diagnostic and therapeutic strategies for varicocele patients.

Effects of Magnesium Sulfate Administration on Testicular Ischemia/Reperfusion Injury in Rats

This study aimed at investigating the effects of intraperitoneal (IP) administration of magnesium sulfate (MgSO4) on testicular ischemia-reperfusion (IR) injury in rats. In total, 50 adult Wistar rats were randomly divided into 5 groups. Group 1 received no injection (control); however, group 2 was subjected to 2 h of I and 24 h of R. Subsequently, group 3 was subjected to 2 h of 1, and after 1 h of I, 125 mg/kg MgSO4 was injected intraperitoneally followed by 24 h of R. Groups 4 and 5 were subjected to the same process as group 3, whereas the rats were injected with 250 and 500 mg/kg of MgSO4, respectively. After 24 h, the left testes of all rats were removed for histological analysis and antioxidant activities. According to the results, there was a significant increase in tissue malondialdehyde (MDA) among I/R rats (P&amp;lt;0.05), whereas MgSO4 decreased I/R-induced MDA (P&amp;lt;0.05). Furthermore, experimental I/R diminished glutathione peroxidase (GPx) and superoxide dismutase (SOD) levels significantly (P&amp;lt;0.05). Moreover, MgSO4 (250 and 500 mg/kg) increased GPx and SOD activity significantly in I/R rats (P&amp;lt;0.05). Furthermore, seminiferous tubules degenerated, and few spermatocytes were observed in the testis tubules of the I/R rats. Regarding pathological parameters, seminiferous tubules and spermatocyte were normal in the testes of MgSO4 (250 and 500 mg/kg)-treated experimental I/R-induced rats. In conclusion, this study demonstrated the beneficial effects of MgSO4 on testicular IR injury in rats.

Proteomic profiling of stallion spermatozoa suggests changes in sperm metabolism and compromised redox regulation after cryopreservation

Proteomic technologies allow the detection of thousands of proteins at the same time, being a powerful technique to reveal molecular regulatory mechanisms in spermatozoa and also sperm damage linked to low fertility or specific biotechnologies. Modifications induced by the cryopreservation in the stallion sperm proteome were studied using UHPLC/MS/MS. Ejaculates from fertile stallions were collected and split in two subsamples, one was investigated as fresh (control) samples, and the other aliquot frozen and thawed using standard procedures and investigated as frozen thawed subsamples. UHPLC/MS/MS was used to study the sperm proteome under these two distinct conditions and bioinformatic enrichment analysis conducted. Gene Ontology (GO) and pathway enrichment analysis were performed revealing dramatic changes as consequence of cryopreservation. The terms oxidative phosphorylation, mitochondrial ATP synthesis coupled electron transport and electron transport chain were significantly enriched in fresh samples (P = 5.50 × 10^-12, 4.26 × 10^-8 and 7.26 × 10^-8, respectively), while were not significantly enriched in frozen thawed samples (P = 1). The GO terms oxidation reduction process and oxidoreductase activity were enriched in fresh samples and the enrichment was reduced in frozen thawed samples (1.40 × 10^-8, 1.69 × 10^-6 versus 1.13 × 10^-2 and 2-86 × 10^-2 respectively). Reactome pathways (using human orthologs) significantly enriched in fresh sperm were TCA cycle and respiratory electron transport (P = 1.867 × 10^-8), Respiratory electron transport ATP synthesis by chemiosmosis coupling (P = 2.124 × 10^-5), Citric acid cycle (TCA cycle)(P = 8.395 × 10^-4) Pyruvate metabolism and TCA cycle (P = 3.380 × 10^-3), Respiratory electron transport (P = 2.764 × 10^-2) and Beta oxidation of laurolyl-CoA to decanoyl CoA-CoA (P = 1.854 × 10^-2) none of these pathways were enriched in thawed samples (P = 1). We have provided the first detailed study on how the cryopreservation process impacts the stallion sperm proteome. Our findings identify the metabolic proteome and redoxome as the two key groups of proteins affected by the procedure. SIGNIFICANCE: In the present manuscript we investigated how the cryopreservation of stallion spermatozoa impacts the proteome of these cells. This procedure is routinely used in horse breeding and has a major impact in the industry, facilitating the trade of genetic material. This is still a suboptimal biotechnology, with numerous unresolved problems. The limited knowledge of the molecular insults occurring during cryopreservation is behind these problems. The application and development of proteomics to the spermatozoa, allow to obtain valuable information of the specific mechanisms affected by the procedure. In this paper, we report that cryopreservation impacts numerous proteins involved in metabolism regulation (mainly mitochondrial proteins involved in the TCA cycle, and oxidative phosphorylation) and also affects proteins with oxidoreductase activity. Moreover, specific proteins involved in the sperm-oocyte interaction are also affected by the procedure. The information gathered in this study, opens interesting questions and offer new lines of research for the improvement of the technology focusing the targets here identified, and the specific steps in the procedure (cooling, toxicity of antioxidants etc.) to be modified to reduce the damage.

Proteomic Analyses of Human Sperm Cells: Understanding the Role of Proteins and Molecular Pathways Affecting Male Reproductive Health

Human sperm proteomics research has gained increasing attention lately, which provides complete information about the functional state of the spermatozoa. Changes in the sperm proteome are evident in several male infertility associated conditions. Global proteomic tools, such as liquid chromatography tandem mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight, are used to profile the sperm proteins to identify the molecular pathways that are defective in infertile men. This review discusses the use of proteomic techniques to analyze the spermatozoa proteome. It also highlights the general steps involved in global proteomic approaches including bioinformatic analysis of the sperm proteomic data. Also, we have presented the findings of major proteomic studies and possible biomarkers in the diagnosis and therapeutics of male infertility. Extensive research on sperm proteome will help in understanding the role of fertility associated sperm proteins. Validation of the sperm proteins as biomarkers in different male infertility conditions may aid the physician in better clinical management.

Heat Induces Oxidative Stress: Reproductive Organ Weights and Serum Metabolite Profile, Testes Structure, and Function Impairment in Male Cavy (Cavia porcellus)

The present study was designed to evaluate the effects of heat that induces oxidative stress on reproduction organ weight and serum biochemical, testes structure, and function in male guinea pig (Cavia porcellus). Forty-eight male guinea pigs with an average weight of 330.56 ± 23.62 g, aged 3–4 months, were distributed into four groups of 12 animals each. One group (control) was maintained to ambient temperature (20–25°C), while other groups (Groups 2–4) were exposed daily for 6 h, to 32 ± 1°C, 39±1°C, and 46 ± 1°C, respectively. All animals were sacrificed after 60 days' exposure and their reproductive characteristics values were determined. Results revealed a significant decrease (p < 0.05) of the weight of testes, epididymis, vas deferens, and accessory glands in cavies exposed to the highest temperature investigated (46 ± 1°C), compared to the control animals. There was a significant (p < 0.05) reduction of serum testosterone and LH levels in all heat stress-exposed groups (≥46 ± 1°C) when compared to the control group. Heat stress significantly (p < 0.05) decreased sperm mobility, sperm count, and testicular antioxidant enzymes, while increasing testicular malondialdehyde content. However, the serum level of HSP-40 increased in the animals exposed to 39 ± 1°C and decreased when the cavies were exposed to 46 ± 1°C. In conclusion, exposure to heat-induced oxidative stress results in impairment of reproduction organ weight and serum biochemical, testes structure, and function in male cavies.

High-intensity interval training modulates male factor infertility through anti-inflammatory and antioxidative mechanisms in infertile men: A randomized controlled trial

The effects of 24 weeks of high-intensity interval training (HIIT) on markers of male reproductive function in infertile patients were studied. Infertile men (n = 441) were randomized to exercise (EX, n = 221) or non-exercise (NON-EX, n = 220) group. Patients in the EX group performed an interval training (1:1 work:rest ratio) 3 times per week at 75-95% of maximal oxygen consumption, for 24 weeks (VO_2max). Markers of inflammation and oxidative stress in the seminal plasma, as well as semen parameters, sperm DNA fragmentation and rates of pregnancy, were measured at baseline, on weeks 12, 24; and 7 and 30 days thereafter during the recovery period. The intervention resulted in decreased seminal levels of proinflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) and markers of oxidative stress (ROS, MDA, and 8-isoprostane) (P < 0.05). The concentrations of seminal antioxidants were unaltered with HIIT intervention. These changes further coincide with promising developments in semen parameters, sperm DNA integrity and rates of pregnancy (P < 0.05). This may indicate that HIIT induced beneficial effects on markers of male reproductive function through decreased oxidative damage and proinflammatory status. Findings highlight the possibility that HIIT may be an effective intervention for male factor infertility and support the need for further human studies.

Male Oxidative Stress Infertility (MOSI): Proposed Terminology and Clinical Practice Guidelines for Management of Idiopathic Male Infertility

Despite advances in the field of male reproductive health, idiopathic male infertility, in which a man has altered semen characteristics without an identifiable cause and there is no female factor infertility, remains a challenging condition to diagnose and manage. Increasing evidence suggests that oxidative stress (OS) plays an independent role in the etiology of male infertility, with 30% to 80% of infertile men having elevated seminal reactive oxygen species levels. OS can negatively affect fertility via a number of pathways, including interference with capacitation and possible damage to sperm membrane and DNA, which may impair the sperm's potential to fertilize an egg and develop into a healthy embryo. Adequate evaluation of male reproductive potential should therefore include an assessment of sperm OS. We propose the term Male Oxidative Stress Infertility, or MOSI, as a novel descriptor for infertile men with abnormal semen characteristics and OS, including many patients who were previously classified as having idiopathic male infertility. Oxidation-reduction potential (ORP) can be a useful clinical biomarker for the classification of MOSI, as it takes into account the levels of both oxidants and reductants (antioxidants). Current treatment protocols for OS, including the use of antioxidants, are not evidence-based and have the potential for complications and increased healthcare-related expenditures. Utilizing an easy, reproducible, and cost-effective test to measure ORP may provide a more targeted, reliable approach for administering antioxidant therapy while minimizing the risk of antioxidant overdose. With the increasing awareness and understanding of MOSI as a distinct male infertility diagnosis, future research endeavors can facilitate the development of evidence-based treatments that target its underlying cause.

Sperm and Seminal Plasma Proteomics: Molecular Changes Associated with Varicocele-Mediated Male Infertility

Male infertility is a rising problem and the etiology at the molecular level is unclear. Use of omics has provided an insight into the underlying cellular changes in the spermatozoa of infertile men. Proteomics is one the promising omics techniques for biomarker screening that can provide complete information on molecular processes associated with male infertility. Varicocele is a pressing issue in the field of male infertility and the search for an appropriate diagnostic and therapeutic biomarker is still ongoing. In this review, we discuss the reports on proteomic profiles of sperm and seminal plasma in male infertility and provide an in-depth insight into varicocele studies associated with male infertility.