Clinical relevance of oxidative stress and sperm chromatin damage in male infertility: an evidence based analysis

Advancements in Understanding and Enhancing Antioxidant-Mediated Sperm Cryopreservation in Small Ruminants: Challenges and Perspectives

Cryopreservation poses significant challenges to the preservation of sperm integrity and function, particularly in small ruminants where cryodamage is pronounced. This review explores the molecular mechanisms underlying sperm cryodamage and strategies for improving cryopreservation outcomes, with a focus on the role of antioxidants. Cryopreservation-induced alterations in proteins and RNA transcripts critical for sperm function, including motility, capacitation, fertilization, and embryo development, are discussed. Proteomic, transcriptomic, and epigenomic advancements have provided valuable insights into these mechanisms, offering potential biomarkers for predicting sperm freezability and enhancing cryopreservation strategies. Combining technologies such as mass spectrometry and flow cytometry allows for a comprehensive understanding of molecular and cellular changes induced by the freezing-thawing process. However, challenges remain in optimizing cryoprotectant formulations and antioxidant supplementation to improve post-thaw sperm fertility. Further research is needed to explore a wider range of novel cryoprotectants, antioxidants, and proteins for cryopreservation media, as well as to validate their efficacy in enhancing sperm viability and function. Additionally, investigations into the effects of cryopreservation on RNA transcripts and epigenetic factors in small ruminant species are warranted to advance our understanding of sperm preservation. Overall, this review highlights the importance of antioxidants in mitigating cryodamage and underscores the need for continued research to refine cryopreservation protocols and improve reproductive outcomes in small ruminants.

The protective effects of curcumin against cigarette smoke-induced toxicity: A comprehensive review

Cigarette smoking (CS) is a crucial modifiable risk of developing several human diseases and cancers. It causes lung, bladder, breast, and esophageal cancers, respiratory disorders, as well as cardiovascular and metabolic diseases. Because of these adverse health effects, continual efforts to decrease the prevalence and toxicity of CS are imperative. Until the past decades, the impacts of natural compounds have been under investigation on the harmful effects of CS. Turmeric (Curcuma longa), a rhizomatous herbaceous perennial plant that belongs to the Zingiberaceae family, is the main source of curcumin. This review is an attempt to find out the current knowledge on CS's harmful effects and protective potential of curcumin in the pulmonary, liver, brain, gastrointestinal, and testis organs. According to the present review, simultaneous consumption of curcumin and CS can attenuate CS toxicities including chronic obstructive pulmonary disease, gastrointestinal toxicity, metabolic diseases, testis injury, and neurotoxicity. Moreover, curcumin suppresses carcinogenesis in the skin, liver, lungs, breast, colon, and stomach. Curcumin mediates these protective effects through antioxidant, anti-inflammatory, anti-apoptotic, and anti-carcinogenicity properties.

Selection of spermatozoa with high motility and quality from bovine frozen-thawed semen using the centrifuge-free device

This study aimed to assess the potential of the centrifuge-free commercial device (MIGLIS®) in selecting functional frozen-thawed bovine sperm by migration-sedimentation, its effect on embryo development, and compare the potential with that of centrifugation-based techniques, including washing and Percoll density gradient centrifugation (DGC). In experiment 1, different dilutions (1.5×, 2×, and 3×) of frozen-thawed spermatozoa were assessed to identify the adequate one for the MIGLIS method. In experiment 2, the recovery rates, quality, and reactive oxygen species (ROS) concentrations of the spermatozoa selected using MIGLIS, washing, and Percoll DGC were compared. In experiment 3, the resultant in vitro fertilised embryos from spermatozoa selected using the three methods were evaluated for blastocyst formation rates and intracellular ROS concentrations at the 2-4 cell stage. The intracellular ROS concentrations were investigated using 2', 7'-dichlorodihydrofluorescein diacetate staining. Using the MIGLIS device, significantly more spermatozoa were recovered at 2× dilution compared with the other dilution ratio, but the motility was not affected by the dilution ratio. On the selection of spermatozoa using the three methods, employing MIGLIS decreased the recovery rates. However, the MIGLIS method increased motility, viability, and acrosome integrity rates compared to those in spermatozoa from the other methods. The ROS concentration of spermatozoa in the MIGLIS method was significantly lower than that in the washing method. Nevertheless, blastocyst formation rates were similar among the three methods, but the ROS concentration of early-stage embryos produced using MIGLIS was significantly lower than those produced using Percoll DGC. In conclusion, the MIGLIS method has the potential to select functional, high-quality frozen-thawed bovine spermatozoa.

How Food Choices Impact on Male Fertility

PURPOSE OF REVIEW

Increasing evidence on the significance of nutrition in reproduction is emerging from both animal and human studies, suggesting an association between nutrition and male fertility. Here, we have highlighted the impact of the various food groups on reproductive hormones and on spermatogenesis, and the effects of classical and latest dietary patterns such as Mediterranean diet, Western diet, intermittent fasting, ketogenic diet, and vegan/vegetarian diet on male fertility.

RECENT FINDINGS

Nutrients are the precursors of molecules involved in various body's reactions; therefore, their balance is essential to ensure the correct regulation of different systems including the endocrine system. Hormones are strongly influenced by the nutritional status of the individual, and their alteration can lead to dysfunctions or diseases like infertility. In addition, nutrients affect sperm production and spermatogenesis, controlling sexual development, and maintaining secondary sexual characteristics and behaviors. The consumption of fruit, vegetables, fish, processed meats, dairy products, sugars, alcohol, and caffeine importantly impact on male fertility. Among dietary patterns, the Mediterranean diet and the Western diet are most strongly associated with the quality of semen. Nutrients, dietary patterns, and hormonal levels have an impact on male infertility. Therefore, understanding how these factors interact with each other is important for strategies to improve male fertility.

Comparing the clinical and singleton neonatal outcomes in male infertility patients with Oligoasthenospermia, OA, or NOA following fresh ICSI-ET using different sources of sperm

Objective

To investigate clinical and singleton newborn outcomes in fresh cycles of embryo transfer after intracytoplasmic sperm injection (ICSI-ET) with diverse sperm sources (ejaculate, epididymis, and testis) in patients with Oligoasthenospermia, obstructive azoospermia (OA) or non-obstructive azoospermia (NOA).

Methods

Patients who received fresh ICSI-ET for the first time at the First Affiliated Hospital of Zhengzhou University Reproductive Medicine Center between June 2011 and June 2021 were selected for this 10-year retrospective cohort analysis. After propensity score matching, only 1630 cycles were included in the investigation of ICS-ET clinical and singleton newborn outcomes in patients with Oligoasthenospermia, OA, and NOA using sperm from diverse sperm sources.

Results

After propensity score matching, our data revealed a negligible difference in baseline and cycle parameters among groups. In patients with Oligoasthenospermia and OA, different sperm sources do not appear to influence clinical pregnancy rates and live birth rates, nor do they influence newborn outcomes, such as newborn weight, premature birth rate, and neonatal sex ratio in singleton births, except for OA patients who use epididymal sperm having higher low birth weight (LBW) rates in singleton pregnancies than those who use testicular sperm. In addition, clinical pregnancy rates, live birth rates, singleton gestation birth weights, premature birth rates, and neonatal sex ratios were similar between patients with Oligoasthenospermia, OA, and NOA using testicular sperm.

Conclusions

Regardless of the type of male infertility (Oligoasthenospermia, OA, NOA) or sperm sources (ejaculate, epididymis, testis), a successful ICSI-ET procedure can result in similar clinical and neonatal outcomes, such as clinical pregnancy rate, live birth rate, abortion rate, neonatal birth weight and sex ratio of singleton pregnancies.

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.

The Role of Melatonin to Ameliorate Oxidative Stress in Sperm Cells

It is widely accepted that oxidative stress (OS) coming from a wide variety of causes has detrimental effects on male fertility. Antioxidants could have a significant role in the treatment of male infertility, and the current systematic review on the role of melatonin to ameliorate OS clearly shows that improvement of semen parameters follows melatonin supplementation. Although melatonin has considerable promise, further studies are needed to clarify its ability to preserve or restore semen quality under stress conditions in varied species. The present review examines the actions of melatonin via receptor subtypes and its function in the context of OS across male vertebrates.

New Insights on Sperm Function in Male Infertility of Unknown Origin: A Multimodal Approach

The global trend of rising (male) infertility is concerning, and the unidentifiable causes in half of the cases, the so-called unknown origin male infertility (UOMI), demands a better understanding and assessment of both external/internal factors and mechanisms potentially involved. In this work, it was our aim to obtain new insight on UOMI, specifically on idiopathic (ID) and Unexplained male infertility (UMI), relying on a detailed evaluation of the male gamete, including functional, metabolic and proteomic aspects. For this purpose, 1114 semen samples, from males in couples seeking infertility treatment, were collected at the Reproductive Medicine Unit from the Centro Hospitalar e Universitário de Coimbra (CHUC), from July 2018-July 2022. Based on the couples' clinical data, seminal/hormonal analysis, and strict eligibility criteria, samples were categorized in 3 groups, control (CTRL), ID and UMI. Lifestyle factors and anxiety/depression symptoms were assessed via survey. Sperm samples were evaluated functionally, mitochondrially and using proteomics. The results of Assisted Reproduction Techniques were assessed whenever available. According to our results, ID patients presented the worst sperm functional profile, while UMI patients were similar to controls. The proteomic analysis revealed 145 differentially expressed proteins, 8 of which were specifically altered in ID and UMI samples. Acrosin (ACRO) and sperm acrosome membrane-associated protein 4 (SACA4) were downregulated in ID patients while laminin subunit beta-2 (LAMB2), mannose 6-phosphate isomerase (MPI), ATP-dependent 6-phosphofructokinase liver type (PFKAL), STAR domain-containing protein 10 (STA10), serotransferrin (TRFE) and exportin-2 (XPO2) were downregulated in UMI patients. Using random forest analysis, SACA4 and LAMB2 were identified as the sperm proteins with a higher chance of distinguishing ID and UMI patients, and their function and expression variation were in accordance with the functional results. No alterations were observed in terms of lifestyle and psychological factors among the 3 groups. These findings obtained in an experimental setting based on 3 well-defined groups of subjects, might help to validate new biomarkers for unknown origin male infertility (ID and UMI) that, in the future, can be used to improve diagnostics and treatments.

SUMO1 and Defective Spermatozoa Correlate with Endogenous Hydrogen Peroxide and Live Birth Outcome in Intrauterine Insemination Cycles for Unexplained Infertility

This study aimed to investigate the correlation between hydrogen peroxide (H2O2), small ubiquitin-like modifier molecules (SUMO), and pregnancy outcomes in couples with unexplained infertility (UI) undergoing intrauterine insemination (IUI) treatment. We prospectively collected semen samples from 56 couples with UI and divided the spermatozoa into motile and immotile fractions by density gradient centrifugation (DSC). Immunofluorescence staining was used to examine the immunostaining and localization of nuclear pore complex (NPC), SUMO1, and SUMO2/3 in spermatozoa. We detected H2O2 levels by chemiluminescence methods. We found that H2O2 levels correlated with NPC (neck) (r = 0.400) and NPC (tail) (r = 0.473) in motile sperm fractions. In immotile fractions, H2O2 positively correlated with NPC (tail) (r = 0.431) and SUMO1 (neck) (r = 0.282). Furthermore, the positive NPC (tail) group had a significantly lower live birth rate than the negative NPC group (17.9% = 5/28 vs. 42.9% = 12/28). In conclusion, H2O2 positively correlated with SUMO1 (neck) and NPC (tail) in human spermatozoa. The DSC may partially eliminate defective spermatozoa (positive NPC staining); however, if defective spermatozoa remain in the motile fraction, this scenario is associated with a low live birth rate following IUI treatment.

The Impact of Oxidative Stress on Male Reproductive Function: Exploring the Role of Antioxidant Supplementation

Male reproductive function is highly susceptible to oxidative stress, which arises from an imbalance between reactive oxygen species (ROS) production and antioxidant defense mechanisms. Oxidative stress can significantly impair sperm quality, including count, motility, morphology, and DNA integrity, leading to male infertility. Antioxidants play a crucial role in maintaining reproductive health by neutralizing ROS and protecting sperm cells from oxidative damage. This review article explores the impact of oxidative stress on male reproductive function and investigates the potential benefits of antioxidant supplementation in mitigating its detrimental effects. A comprehensive literature search was conducted to gather relevant studies examining the effects of oxidative stress on male fertility and the outcomes of antioxidant supplementation. The findings reveal that antioxidant supplementation can improve sperm quality, DNA integrity, and fertility outcomes in some individuals. However, conflicting research findings and limitations in study design highlight the need for further investigation. Factors such as individual variations, underlying causes of infertility, dosage, and duration of supplementation should be carefully considered. Lifestyle modifications, including a healthy diet and exercise, are crucial in reducing oxidative stress and optimizing male reproductive health. This review article provides valuable insights into the complex relationship between oxidative stress and male reproductive function, emphasizing the potential role of antioxidant supplementation as a supportive strategy. Further research is warranted to establish optimal protocols, identify specific subgroups that may benefit the most, and explore advancements in antioxidant therapies to improve male fertility outcomes.

Resumption of Spermatogenesis and Fertility Post Withdrawal of Hydroxyurea Treatment

Hydroxyurea (HU), a drug for treating cancers of the blood and the management of sickle cell anemia, induces hypogonadism in males. However, the impact of HU on testicular architecture and function, as well as its effects on the resumption of male fertility following treatment withdrawal, remain poorly understood. We used adult male mice to determine whether HU-induced hypogonadism is reversible. Fertility indices of mice treated with HU daily for ~1 sperm cycle (2 months) were compared with those of their control counterparts. All indices of fertility were significantly reduced among mice treated with HU compared to controls. Interestingly, significant improvements in fertility indices were apparent after a 4-month withdrawal from HU treatment (testis weight: month 1 post-HU withdrawal (M1): HU, 0.09 ± 0.01 vs. control, 0.33 ± 0.03; M4: HU, 0.26 ± 0.03 vs. control, 0.37 ± 0.04 g); sperm motility (M1: HU,12 vs. 59; M4: HU, 45 vs. control, 61%; sperm density (M1: HU, 1.3 ± 0.3 vs. control, 15.7 ± 0.9; M4: HU, 8.1 ± 2.5 vs. control, 16.8 ± 1.9 million). Further, circulating testosterone increased in the 4th month following HU withdrawal and was comparable to that of controls. When a mating experiment was conducted, recovering males sired viable offspring with untreated females albeit at a lower rate than control males (p < 0.05); therefore, qualifying HU as a potential candidate for male contraception.

In vitro effects of plasma rich in growth factors on human teratozoospermic semen samples

There is a correlation between teratozoospermia and production of reactive oxygen species leading to poor assisted reproductive techniques outcomes. This study aimed to examine the effect of plasma-rich in growth factors (PRGF) on teratozoospermic samples. Twenty-five teratozoospermic samples were included in this study. After sperm preparation, it was divided into four groups, including 0 (control), 1, 5, and 10% PRGF. Sperm motility, viability (eosin-nigrosin staining), morphology (Papanicolaou staining), DNA fragmentation (sperm chromatin dispersion test), mitochondrial membrane potential (JC-1 staining by flow cytometry), and lipid peroxidation (measurement of malondialdehyde, MDA) were evaluated before and after 1 h of incubation with or without PRGF. Our results showed that after 1 h of incubation, the addition of 1% PRGF improved sperm progressive motility (47.72 ± 13.76%) compared to the control group (17.36 ± 8.50%) (p < 0.001). Also, 1% PRGF preserved the sperm's total motility (77.50 ± 13.28% vs. 65.63 ± 19.03%, for 1% PRGF and control, respectively) and viability after incubation. The rate of normal sperm morphology was the same between different groups. Higher mitochondrial membrane potential and lower DNA fragmentation were also observed in sperm treated with different concentrations of PRGF compared to the control group, but the differences were non-significant. The MDA levels were significantly decreased in PRGF-treated groups compared to the control group (0.99 ± 0.62, 0.95 ± 0.33, 0.95 ± 0.79, and 1.49 ± 0.27 for 1% PRGF, 5% PRGF, 10% PRGF and control, respectively). Based on our results, it seems that PRGF incubation can improve sperm parameters and especially decrease the level of malondialdehyde as an indicator of oxidative stress, which is one of the main problems of teratozoospermic samples.

Relation between semen oxidative reduction potential in initial semen examination and IVF outcomes

Purpose

The MiOXSYS system is a new technique to analyze the semen oxidative reduction potential (ORP) that may use to classify the level of sperm DNA integrity. It does not clearly explain how the semen ORP values could help to change the IVF outcomes. We have analyzed correlations between semen ORP value and the IVF results.

Methods

Four hundred and thirty couples were enrolled. The male counterparts were divided into two groups according to their semen ORP values and compared the fertilization rate, cell cleavage rate, and embryo quality, following the IVF procedures. The relations between ORP values and the clinical pregnancy, live birth, and abortion rates were analyzed.

Results

The ORP values show negative and positive correlations with some conventional semen parameters. The fertilization and the cleavage rate did not show any differences in those two groups, but the transferable embryo rate was significantly high in patients with high semen ORP. However, the patients with high ORP show a tendency to lower clinical pregnancy with a low abortion rate compared to the low ORP group.

Conclusion

The main purpose of measuring the ORP value in semen is still questionable and shows controversial results.

Beneficial effects of trehalose and gentiobiose on human sperm cryopreservation

The protection of human sperm during cryopreservation is of great importance to infertility. Recent studies have shown that this area is still a long way from its ultimate aim of maintaining the maximum viability of sperm in cryopreservation. The present study used trehalose and gentiobiose to prepare the human sperm freezing medium during the freezing-thawing. The freezing medium of sperm was prepared with these sugars, and the sperm were then cryopreserved. The viable cells, sperm motility parameters, sperm morphology, membrane integrity, apoptosis, acrosome integrity, DNA fragmentation, mitochondrial membrane potential, reactive oxygen radicals, and malondialdehyde concentration was evaluated using standard protocols. A higher percentage of the total and progressive motility, rate of viable sperm, cell membrane integrity, DNA and acrosome integrity, and mitochondrial membrane potential were observed in the two frozen treatment groups compared to the frozen control. The cells had less abnormal morphology due to treatment with the new freezing medium than the frozen control. The higher malondialdehyde and DNA fragmentation were significantly observed in the two frozen treatment groups than in the frozen control. According to the results of this study, the use of trehalose and gentiobiose in the sperm freezing medium is a suitable strategy for sperm freezing to improve its motion and cellular parameters.

Nanoscale MRI for Selective Labeling and Localized Free Radical Measurements in the Acrosomes of Single Sperm Cells

Free radicals play a major role in sperm development, including maturation and fertilization, but they are also linked to infertility. Since they are short-lived and reactive, they are challenging to detect with state of the art methodologies. Thus, many details surrounding their role remain unknown. One unknown factor is the source of radicals that plays a role in the sperm maturation process. Two alternative sources have been postulated: First, the NADPH-oxidase system embedded in the plasma membrane (NOX5) and second, the NADH-dependent oxidoreductase of mitochondria. Due to a lack of localized measurements, the relative contribution of each source for capacitation remains unknown. To answer this question, we use a technique called diamond magnetometry, which allows nanoscale MRI to perform localized free radical detection. With this tool, we were able to quantify radical formation in the acrosome of sperm heads. This allowed us to quantify radical formation locally in real time during capacitation. We further investigated how different inhibitors or triggers alter the radical generation. We were able to identify NOX5 as the prominent source of radical generation in capacitation while the NADH-dependent oxidoreductase of mitochondria seems to play a smaller role.

Chlorella vulgaris ameliorates testicular toxicity induced by carbon tetrachloride in male rats via modulating oxidative stress

This study was aimed to evaluate the protective effects of Chlorella Vulgaris (CVE) (50 and 100 mg/kg doses) on sperm DNA fragmentation, testis oxidative stress in Carbon tetrachloride (CCL4)-exposed rats. Thirty healthy male Wistar rats were divided into five groups (n = 6): Control; CCl4; CVE; CCl4 + CVE50; CCl4 + CVE100. At the end of the experiment, the testicular oxidative stress parameters were estimated. The Chromomycin A3 (CMA3) and Acridine orange (AO) staining were performed to examine the sperm DNA fragmentation status. CCl4 treatment showed a significant decrease in antioxidant markers and sperm count, viability, normal morphology and motility as well as significantly increased the testicular oxidative stress markers, and the percentage of CMA3 and AO positive sperms in normal rats (p < 0.05). While CVE supplementation has revealed a significant decrease in the percentage of CMA3 and AO positive sperms as well as testicular oxidative stress markers and considerably improved the testis antioxidant status (p < 0.05). CVE has also increased the number of sperms with forwarding movement, normal morphology and viability (p < 0.05). Taken together, our analyses suggest that CVE may play a critical role in attenuating the CCl4-induced oxidative stress in the testis, thereby protecting the sperm membrane and DNA against oxidative damage.

Bacteriospermia and Male Infertility: Role of Oxidative Stress

Male infertility is one of the major challenging and prevalent diseases having diverse etiologies of which bacteriospermia play a significant role. It has been estimated that approximately 15% of all infertility cases are due to infections caused by uropathogens and in most of the cases bacteria are involved in infection and inflammation leading to the development of bacteriospermia. In response to bacterial load, excess infiltration of leukocytes in the urogenital tract occurs and concomitantly generates oxidative stress (OS). Bacteria may induce infertility either by directly interacting with sperm or by generating reactive oxygen species (ROS) and impair sperm parameters such as motility, volume, capacitation, hyperactivation. They may also induce apoptosis leading to sperm death. Acute bacteriospermia is related with another clinical condition called leukocytospermia and both compromise male fertility potential by OS-mediated damage to sperm leading to male infertility. However, bacteriospermia as a clinical condition as well as the mechanism of action remains poorly understood, necessitating further research in order to understand the role of individual bacterial species and their impact in male infertility.

Pathological Roles of Reactive Oxygen Species in Male Reproduction

Reactive oxygen species (ROS) are free radicals that have at least one unpaired electron and play specific roles in the human body. An imbalance of ROS and antioxidant levels gives rise to a condition called oxidative stress. High levels of ROS in the male reproductive tract can interfere with its normal functioning and can even pose as toxic to the sperm, inhibiting sperm functioning (including motility) and metabolism. Oxidative stress resulting from ROS and lipid peroxidation is one of the major causes of male infertility including infertility in varicocele patients. These may cause DNA and peroxidative damage and apoptosis. Production of ROS in excess also leads to erectile dysfunction (ED). In recent years, studies have also linked oxidative stress with the development, progress, and therapy response of prostate cancer patients. The present study summarizes the pathological roles of ROS in male reproductive problems such as infertility, ED, and prostate cancer and also provide an insight into the probable mechanism through which ROS exert their pathological impact.

Effects of Abelmoschus manihot Flower Extract on Enhancing Sexual Arousal and Reproductive Performance in Zebrafish

The flower of Abelmoschus manihot L. is mainly used for the treatment of chronic kidney diseases, and has been reported to have bioactivities such as antioxidant, anti-inflammatory, antiviral, and antidepressant activities. This study used wild-type adult zebrafish as an animal model to elucidate the potential bioactivity of A. manihot flower ethanol extract (AME) in enhancing their sexual and reproductive functions. Zebrafish were fed AME twice a day at doses of 0.2%, 1%, and 10% for 28 days, and were then given the normal feed for an additional 14 days. The hormone 17-β estradiol was used as the positive control. Sexual behavioral parameters such as the number of times males chased female fish, the production of fertilized eggs, and the hatching rate of the fertilized eggs were recorded at days 0.33, 7, 14, 21, 28, and 42. The expression levels of sex-related genes—including lhcgr, ar, cyp19a1a, and cyp19a1b—were also examined. The results showed that the chasing number, fertilized egg production, and hatching rate were all increased with the increase in the AME treatment dose and treatment time. After feeding with 1% and 10% AME for 28 days, the chasing number in the treated group as compared to the control group increased by 1.52 times and 1.64 times, respectively; the yield of fertilized eggs increased by 1.59 times and 2.31 times, respectively; and the hatching rate increased by 1.26 times and 1.69 times, respectively. All three parameters exhibited strong linear correlations with one another (p < 0.001). The expression of all four genes was also upregulated with increasing AME dose and treatment duration. When feeding with 0.2%, 1%, and 10% AME for 28 days, the four sex-related genes were upregulated at ranges of 1.79−2.08-fold, 2.74−3.73-fold, and 3.30−4.66-fold, respectively. Furthermore, the effect of AME was persistent, as the promotion effect continued after the treatment was stopped for at least two weeks. The present findings suggest that AME can enhance the endocrine system and may improve libido and reproductive performance in zebrafish.

The Role of ROS as a Double-Edged Sword in (In)Fertility: The Impact of Cancer Treatment

Simple Summary

Tumor cells are highly resistant to oxidative stress, but beyond a certain threshold, it may lead to apoptosis/necrosis. Thus, induced loss of redox balance can be a strategy used in anticancer therapies. However, the effectiveness of drugs contrasts with unknown mechanisms involved in the loss of fertility. Considering that cancer patients’ life expectancy is increasing, it raises concerns about the unknown adverse effects. Therefore, new strategies should be pursued alongside explaining to the patients their options regarding the reproduction side effects.

Abstract

Tumor cells are highly resistant to oxidative stress resulting from the imbalance between high reactive oxygen species (ROS) production and insufficient antioxidant defenses. However, when intracellular levels of ROS rise beyond a certain threshold, largely above cancer cells’ capacity to reduce it, they may ultimately lead to apoptosis or necrosis. This is, in fact, one of the molecular mechanisms of anticancer drugs, as most chemotherapeutic treatments alter redox homeostasis by further elevation of intracellular ROS levels or inhibition of antioxidant pathways. In traditional chemotherapy, it is widely accepted that most therapeutic effects are due to ROS-mediated cell damage, but in targeted therapies, ROS-mediated effects are mostly unknown and data are still emerging. The increasing effectiveness of anticancer treatments has raised new challenges, especially in the field of reproduction. With cancer patients’ life expectancy increasing, many aiming to become parents will be confronted with the adverse effects of treatments. Consequently, concerns about the impact of anticancer therapies on reproductive capacity are of particular interest. In this review, we begin with a short introduction on anticancer therapies, then address ROS physiological/pathophysiological roles in both male and female reproductive systems, and finish with ROS-mediated adverse effects of anticancer treatments in reproduction.

Oxidative Stress and Male Infertility: Evidence From a Research Perspective

Male fertility potential can be influenced by a variety of conditions that frequently coincide. Spermatozoa are particularly susceptible to oxidative damage due to their limited antioxidant capacity and cell membrane rich in polyunsaturated fatty acids (PUFAs). The role of oxidative stress (OS) in the etiology of male infertility has been the primary focus of our Stellenbosch University Reproductive Research Group (SURRG) over the last 10 years. This review aims to provide a novel insight into the impact of OS on spermatozoa and male reproductive function by reviewing the OS-related findings from a wide variety of studies conducted in our laboratory, along with those emerging from other investigators. We will provide a concise overview of the production of reactive oxygen species (ROS) and the development of OS in the male reproductive tract along with the physiological and pathological effects thereof on male reproductive functions. Recent advances in methods and techniques used for the assessment of OS will also be highlighted. We will furthermore consider the current evidence regarding the association between OS and ejaculatory abstinence period, as well as the potential mechanisms involved in the pathophysiology of various systemic diseases such as obesity, insulin resistance, hypertension, and certain mental health disorders which have been shown to cause OS induced male infertility. Finally, special emphasis will be placed on the potential for transferring and incorporating research findings emanating from different experimental studies into clinical practice.

Andrological Aspects of Exercise: Moderate Swimming Protects against Isoproterenol Induced Testis and Semen Abnormalities in Rats

The development and progression of male infertility are closely linked to a sedentary lifestyle; however, its underlying mechanisms are not fully elucidated. Our aim was to assess the protective effects of moderate swimming exercise on the male reproductive system in isoproterenol-treated rats. Male Wistar rats were divided into five groups as follows: (1) non-interventional controls (CTRL), (2) isoproterenol-treated (ISO), (3) pre-treatment swimming training + ISO (PRE + ISO), (4) ISO + post-treatment swimming training (ISO+POST), (5) pre-treatment swimming training + ISO + post-treatment swimming training (PRE + ISO + POST) groups. Testicular oxidative stress was induced by ISO injection (1.0 mg/kg). Rats in the pre- or post-training groups were trained five days a week. At the end of the experimental period, serum testosterone levels, sperms’ hyaluronan binding, and total glutathione (GSH) content, as well as myeloperoxidase activity (MPO), TNF alpha and IL6 concentrations in the testis and semen, were measured. Serum testosterone levels, sperms’ hyaluronan binding, and GSH content were found to be significantly reduced, while MPO, TNF alpha and IL6 concentrations in the testis and semen were elevated after the ISO treatment compared to the CTRL group. Moderate-intensity swimming exercise effectively alleviated the negative effects of high oxidative stress. Our findings provide the first evidence that moderate-intensity swimming exercise confers sustained protection from isoproterenol-induced adverse effects on testicular inflammation.

Supplementation of freezing medium with encapsulated or free glutathione during cryopreservation of bull sperm

The objective was to compare effects of encapsulated or free glutathione (GSH) on quality of frozen-thawed bull sperm. Ejaculates were collected via artificial vagina from six mature Holstein bulls once weekly for 6 weeks. All ejaculates had motility ≥70%, sperm concentration ≥1.0 × 10⁹ /mL and ≤15% morphologically abnormal sperm. Each week, semen was pooled and diluted with lecithin-based extenders containing various concentrations of encapsulated (E0, E1, E2.5 and E5 mM) or free (F0, F1, F2.5 and F5 mM) GSH, with total glutathione content determined before and after cryopreservation. Total GSH in fresh semen was (mean+SEM) 4.8 ± 0.2 nmol/10⁸ sperm, whereas in frozen-thawed semen of group F0 (control), it decreased to 1.4 ± 0.2 nmol/10⁸ sperm, a 70.8% reduction (P<0.05). In addition, total GSH in frozen-thawed semen from groups E2.5, E5 and F5 were 2.4 ± 0.2, 2.8 ± 0.2 and 1.8 ± 0.2 nmol/10⁸ sperm, respectively (E5 vs. F0, P<0.05). Compared to group F0, frozen-thawed sperm from group E2.5 had greater (P<0.05) percentages of sperm that were viable (Annexin-V) (61.1 ± 1.8 vs 71.1 ± 1.8) and that had cell membrane integrity (eosin-nigrosin) (64.5 ± 3.1 vs 80.0 ± 3.1). Furthermore, frozen-thawed sperm from group E2.5 had the numerically highest total and progressive motility (CASA) and cell membrane functionality (HOS) and the lowest percentage of early apoptotic sperm (Annexin-V). However, acrosome membrane integrity (PSA) of E5 had the lowest mean (P<0.05), whereas E2.5 caused a small nonsignificant decrease (69.1 ± 1.4%) compared to E0 and F0. In conclusion, 2.5 mM encapsulated GSH in semen extender significantly improved the quality of frozen-thawed bull sperm.

Arsenic-Induced Sex Hormone Disruption: An Insight into Male Infertility

Arsenic (As) is one of the most potent natural as well as anthropogenic metalloid toxicants that have various implications in the everyday life of humans. It is found in several chemical forms such as inorganic salt, organic salt, and arsine (gaseous form). Although it is mostly released via natural causes, there are many ways through which humans come in contact with As. Drinking water contamination by As is one of the major health concerns in various parts of the world. Arsenic exposure has the ability to induce adverse health effects including reproductive problems. Globally, around 15% of the couples are affected with infertility, of which about 20-30% are attributed to the male factor. Arsenic affects the normal development and function of sperm cells, tissue organization of the gonads, and also the sex hormone parameters. Stress induction is one of the implications of As exposure. Excessive stress leads to the release of glucocorticoids, which impact the oxidative balance in the body leading to overproduction of reactive oxygen species (ROS). This may in turn result in oxidative stress (OS) ultimately interfering with normal sperm and hormonal parameters. This study deals with As-induced OS and its association with sex hormone disruption as well as its effect on sperm and semen quality.

Effect of curcumin on sperm parameters after the cryopreservation

OBJECTIVE

Cryopreservation refers to the cooling of cells and tissues to sub-zero temperatures in order to stop all biologic activity and preserve them for future use. Human sperm cryopreservation is an important tool for assisted reproductive technology and male fertility preservation. However, cryopreservation significantly reduces the quality of spermatozoa. The antioxidant effects of curcumin on different cells have been widely reported. This study was aimed to evaluate changes in post-thaw viability, morphology, motility, chromatin condensation and DNA integrity in response to the addition of curcumin to human sperm freezing extender.

MATERIALS AND METHODS

Semen of 23 normozoospermic men was collected and each sample was divided into three equal aliquots: Control, DMSO, Curcumin. The samples were analyzed freshly for viability (Eosin Y), morphology (Diff-Quick), motility (following WHO standarts), sperm chromatin packaging (aniline blue) and DNA integrity (acridine orange). The control group remained untreated and was mixed with cryopreservation medium (in-house 1:1). The DMSO group was mixed with cryopreservation medium containing 0.1% DMSO. The curcumin group was mixed with cryopreservation medium containing 10 µM curcumin. Samples stained with Diff-Quick and aniline blue were examined under light microscope, samples stained with Eosin Y were examined under phase-contrast microscope and samples stained with acridine orange were examined under fluorescence microscope. Ten days after cryopreservation, samples were thawed and pre-freeze analyses repeated.

RESULTS

Obtained results showed that cryopreservation significantly (P < 0.001) reduces sperm parameters. In Curcumin group, progressive motility, sperm chromatin condensation and DNA integrity significantly (P < 0.001) increased after the thawing process, as compared with the control and the DMSO group.

CONCLUSION

These results suggest that the addition of curcumin to cryopreservation medium improves post-thaw progressive motility, sperm chromatin condensation and DNA integrity. It seems that curcumin ameliorates detrimental effects of cryopreservation on human spermatozoa. Further research is needed on the use of curcumin and other antioxidant substances in sperm cryopreservation.

Ulva lactuca methanolic extract improves oxidative stress-related male infertility induced in experimental animals

AIM

This study designated to investigate and compare the therapeutic effect of Ulva lactuca methanolic extract against oxidative stress (OS)-infertility induced by naturally occurring prooxidants (gossypol) and selenium- vitamins A, C, and E (selenium-ACE) drug.

METHODS

Male infertility was induced in rat by intraperitoneal injection of 5 mg/kg gossypol eight times then the treatment was carried out with 100 mg/kg ulva methanolic extract oral administration for one or two weeks, after this period OS, and male infertile markers were detected in blood and/or testes.

RESULTS

Gossypol stimulated male infertility by increasing testicular OS markers and decreasing semen quality, hyaluronidase enzyme activity, and blood testosterone level. The treatment with ulva methanolic extract improved gossypol related adverse effects. The treatment period for two weeks with extract was the most potent one.

CONCLUSIONS

Ulva methanolic extract could be considered as good antioxidant therapeutic candidate for OS linked male infertility.

Redox Balance in Male Infertility: Excellence through Moderation-"Μέτρον ἄριστον"

Male infertility, a relatively common and multifactorial medical condition, affects approximately 15% of couples globally. Based on WHO estimates, a staggering 190 million people struggle with this health condition, and male factor is the sole or contributing factor in roughly 20–50% of these cases. Nowadays, urologists are confronted with a wide spectrum of conditions ranging from the typical infertile male to more complex cases of either unexplained or idiopathic male infertility, requiring a specific patient-tailored diagnostic approach and management. Strikingly enough, no identifiable cause in routine workup can be found in 30% to 50% of infertile males. The medical term male oxidative stress infertility (MOSI) was recently coined to describe infertile men with abnormal sperm parameters and oxidative stress (OS), including those previously classified as having idiopathic infertility. OS is a critical component of male infertility, entailing an imbalance between reactive oxygen species (ROS) and antioxidants. ROS abundance has been implicated in sperm abnormalities, while the exact impact on fertilization and pregnancy has long been a subject of considerable debate. In an attempt to counteract the deleterious effects of OS, urologists resorted to antioxidant supplementation. Mounting evidence indicates that indiscriminate consumption of antioxidants has led in some cases to sperm cell damage through a reductive-stress-induced state. The “antioxidant paradox”, one of the biggest andrological challenges, remains a lurking danger that needs to be carefully avoided and thoroughly investigated. For that reason, oxidation-reduction potential (ORP) emerged as a viable ancillary tool to basic semen analysis, measuring the overall balance between oxidants and antioxidants (reductants). A novel biomarker, the Male infertility Oxidative System (MiOXSYS^®), is a paradigm shift towards that goal, offering a quantification of OS via a quick, reliable, and reproducible measurement of the ORP. Moderation or “Μέτρον” according to the ancient Greeks is the key to successfully safeguarding redox balance, with MiOXSYS^® earnestly claiming its position as a guarantor of homeostasis in the intracellular redox milieu. In the present paper, we aim to offer a narrative summary of evidence relevant to redox regulation in male reproduction, analyze the impact of OS and reductive stress on sperm function, and shed light on the “antioxidant paradox” phenomenon. Finally, we examine the most up-to-date scientific literature regarding ORP and its measurement by the recently developed MiOXSYS^® assay.

Genetic Association in the Maintenance of the Mitochondrial Microenvironment and Sperm Capacity

Sperm motility is one of the major determinants of male fertility. Since sperm need a great deal of energy to support their fast movement by active metabolism, they are thus extremely vulnerable to oxidative damage by the reactive oxygen species (ROS) and other free radicals generated as byproducts in the electron transport chain. The present study is aimed at understanding the impact of a mitochondrial oxidizing/reducing microenvironment in the etiopathology of male infertility. We detected the mitochondrial DNA (mtDNA) 4,977 bp deletion in human sperm. We examined the gene mutation of ATP synthase 6 (ATPase6 m.T8993G) in ATP generation, the gene polymorphisms of uncoupling protein 2 (UCP2, G-866A) in the uncoupling of oxidative phosphorylation, the role of genes such as manganese superoxide dismutase (MnSOD, C47T) and catalase (CAT, C-262T) in the scavenging system in neutralizing reactive oxygen species, and the role of human 8-oxoguanine DNA glycosylase (hOGG1, C1245G) in 8-hydroxy-2′-deoxyguanosine (8-OHdG) repair. We found that the sperm with higher motility were found to have a higher mitochondrial membrane potential and mitochondrial bioenergetics. The genotype frequencies of UCP2 G-866A, MnSOD C47T, and CAT C-262T were found to be significantly different among the fertile subjects, the infertile subjects with more than 50% motility, and the infertile subjects with less than 50% motility. A higher prevalence of the mtDNA 4,977 bp deletion was found in the subjects with impaired sperm motility and fertility. Furthermore, we found that there were significant differences between the occurrences of the mtDNA 4,977 bp deletion and MnSOD (C47T) and hOGG1 (C1245G). In conclusion, the maintenance of the mitochondrial redox microenvironment and genome integrity is an important issue in sperm motility and fertility.

Oxidative Stress and Male Fertility: Role of Antioxidants and Inositols

Infertility is defined as a couple’s inability to conceive after at least one year of regular unprotected intercourse. This condition has become a global health problem affecting approximately 187 million couples worldwide and about half of the cases are attributable to male factors. Oxidative stress is a common reason for several conditions associated with male infertility. High levels of reactive oxygen species (ROS) impair sperm quality by decreasing motility and increasing the oxidation of DNA, of protein and of lipids. Multi-antioxidant supplementation is considered effective for male fertility parameters due to the synergistic effects of antioxidants. Most of them act by decreasing ROS concentration, thus improving sperm quality. In addition, other natural molecules, myo-inositol (MI) and d-chiro–inositol (DCI), ameliorate sperm quality. In sperm cells, MI is involved in many transduction mechanisms that regulate cytoplasmic calcium levels, capacitation and mitochondrial function. On the other hand, DCI is involved in the downregulation of steroidogenic enzyme aromatase, which produces testosterone. In this review, we analyze the processes involving oxidative stress in male fertility and the mechanisms of action of different molecules.

Phytochemical Screening, Antioxidant and Sperm Viability of Nelumbo nucifera Petal Extracts

Sacred lotus (Nelumbo nucifera Gaertn.; N. nucifera) is a common ingredient in traditional medicine and Thai recipes. Its petal is an agricultural waste from stamen production. There are limitations in the used and pharmacological data of the petals resulting in more petals waste. The aims of this study were to investigate the phytochemical contents, antioxidant activity, and potential effects on sperm viability of aqueous (NAE) and ethanolic extracts (NEE) of both red and white N. nucifera petals. The white NAE had the highest total phenolics content, total tannins content and maximal antioxidant activity. The white NEE had the highest concentration of total flavonoids. Quercetin was a major flavonoid and was found in the aqueous extracts. Both red and white of NAE in the range of 0.22 to 1.76 mg/mL increased sperm viability. The white NAE was prominent in phytochemical content, antioxidant activity, and both red and white NAE effectively increased rat sperm viability in the in vitro model. The white NAE enhanced sperm viability by decreasing oxidative stress. It might be suggested that the N. nucifera petals have benefits for sperm viability health promotion and may increase the economic value of agricultural waste.

Correlation of oxidation reduction potential and total motile sperm count: its utility in the evaluation of male fertility potential

Oxidative stress (OS) is detrimental to sperm functions, and the oxidation reduction potential (ORP) is a good measure of OS as it considers the balance between oxidants and reductants. Total motile sperm count (TMSC) is viewed as the single most important semen analysis parameter that can predict male infertility severity, and its correlation with ORP has never been undertaken. The objectives of this study were to assess the correlation between ORP and TMSC, to identify the ORP cutoff value based on the TMSC result, and to compare this cutoff value with previously reported ORP cutoff values in literature. One thousand one hundred and sixty-eight infertile patients and 100 fertile controls were enrolled. Demographic and semen data of the participants were retrieved and analyzed. Wilcoxon's rank-sum test compared variables between infertile men and fertile controls; Spearman's correlation assessed the static ORP (sORP)-TMSC relationship for the whole sample and among each group individually. Using a 20×10⁶ TMSC threshold, receiver operator characteristic (ROC) analysis determined the sORP cutoff associated with the highest predictive values. TMSC was significantly negatively correlated with sORP across all participants (r = 0.86, P < 0.001), among infertile patients (r = 0.729, P < 0.001), and among fertile controls (r = 0.53, P < 0.001). A 20-million TMSC threshold determined an sORP cutoff value of 2.34 mV/10⁶ sperm/ml to be associated with 82.9% sensitivity, 82.8% specificity, 91.5% positive predictive value (PPV), 68.5% negative predictive value (NPV), and 82.9% overall accuracy. Compared with previously reported cutoff values in searched literature, the 2.34 mV/10⁶ sperm/ml cutoff value identified in our study yielded the highest overall diagnostic accuracy in the evaluation of infertile men.

Correlation among isolated teratozoospermia, sperm DNA fragmentation and markers of systemic inflammation in primary infertile men

Aim

To assess the prevalence of isolated teratozoospermia (iTZS) in a cohort of infertile and fertile men; explore the relationship between iTZS, inflammatory parameters and sperm DNA fragmentation index (SDF) in the same cohort.

Materials and methods

1824 infertile men and 103 fertile controls. Semen analysis, the neutrophil-to-lymphocyte ratio (NLR) and serum hormones were investigated. DFI was tested in infertile men only. According to 2010 WHO semen analysis, patients were categorized in 3 sub-groups of isolated sperm defects: isolated oligozoospermia (iOZS), isolated asthenozoospermia (iAZS) and iTZS. Descriptive statistics and linear regression models tested the association between clinical variables and inflammatory markers.

Results

Among infertile men, iAZS, iTZS, and iOZS were found in 13.9%, 11.9% and 4.1% participants, respectively. iTZS was found in 37 (35.9%) fertile men. Infertile men with iTZS had higher NLR values than those with iOZS, iAZS and men with normal semen parameters (all p<0.001). FSH and LH were higher and inhibin B lower in iOZS infertile men compared to all other groups (p≤0.001). Hormonal characteristics were similar between iTZS infertile and fertile men. Similarly, iTZS infertile men had higher SDF than all other groups (all p<0.001). Infertile men with iTZS had higher NLR values than fertile men with iTZS (p<0.01). Linear regression analysis showed that, in infertile men, iTZS was associated with SDF and NLR (all p≤0.01).

Conclusions

iTZS was found in 11.9% of infertile men but it was even more prevalent in fertile controls. Infertile men with iTZS had higher NLR than fertile controls and increased SDF values than infertile participant with iAZS, iOZS, or normal semen parameters. No differences in hormonal characteristics were found between infertile and fertile men with iTZS.

Effects of Pulsed-Wave Photobiomodulation Therapy on Human Spermatozoa

BACKGROUND AND OBJECTIVES

Previous studies reported that photobiomodulation (PBM) positively affects the mitochondrial respiratory chain in sperm, resulting in improved motility and velocity. As laser settings are not yet fully established, the present study aimed at optimizing PBM on human sperm. In addition, possible side-effects of PBM on sperm DNA fragmentation level and acrosomal integrity have been analyzed.

STUDY DESIGN/MATERIALS AND METHODS

A pulsed laser-probe (wavelength 655 nm, output power 25 mW/cm², impulse duration 200 nanoseconds) was used. Native fresh liquefied semen samples underwent radiation with energy doses of 0 (control), 4, 6, and 10 J/cm². Sperm parameters were assessed at 0, 30, 60, 90, and 120 minutes after radiation using a computer-assisted sperm analysis system. Motility and velocity of sperm from asthenozoospermic patients (n = 42) and normozoospermic controls (n = 22) were measured. The amount of DNA strand breaks was analyzed using ligation-mediated quantitative polymerase chain reaction in patients with asthenozoospermia (n = 18) and normozoospermia (n = 13). Post-irradiance acrosomal integrity was investigated using flow cytometry based on CD46 protein expression (n = 7).

RESULTS

Exposure to laser energy-doses of 4 and 6 J/cm² improved sperm motility and velocity in asthenozoospermic patients. PBM exhibited no significant effect on DNA fragmentation level and expression of CD46 serving as a biomarker for acrosome integrity.

CONCLUSION

PBM improves sperm motility parameters by maintaining DNA and acrosome integrity and, therefore, represents a promising new tool for assisted reproductive therapy. In particular, improving sperm motility in asthenozoospermic patients by PBM in future may contribute to increasing the chance for successful intrauterine insemination. The present trial has no clinical registration number, as only in vitro studies were performed. The study was approved by the local ethics committee and performed according to the Declaration of Helsinki. Lasers Surg. Med. © 2021 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.

Effect of Ceratonia siliqua L. extract on DNA Fragmentation of Sperm in Adult Male Mice Treated with Cyclophosphamide

This study was conducted to determine the effects of Ceratonia siliqua L. (CS) extract on sperm parameters and DNA damage in adult male mice treated with cyclophosphamide (CP). Based on an initial dose response experiment on Ceratonia siliqua L. extract, five treatment groups were set up: control, sham (normal saline: 0.2 ml per day, IP), CP (15 mg kg^-1 per week; IP), Ceratonia siliqua L. (100mg l^-1 per day; IP), and group of Ceratonia siliqua L. along with CP for 35 days. After euthanizing the animals, sperms from caudal part of epididymis were collected, and their parameters, Malone Di-Aldehyde (MDA) level, and DNA fragmentation were analyzed. In the mice exposed to cyclophosphamide, reduction in the sperm count and viability and increase in the abnormal sperm and MDA levels were detected (p < .05). In addition, an increase in sperms with damaged DNA was detected in CP group, while the use of Ceratonia siliqua L. Extract significantly recovered these disturbances in the treatment group (p < .05). This study suggested the competence of Ceratonia siliqua L. extract in the improvement of sperm parameters and DNA fragmentation in animals treated with CP.

Multiparametric Study of Antioxidant Effect on Ram Sperm Cryopreservation-From Field Trials to Research Bench

Simple Summary

The use of antioxidant compounds could be a successful tool to improve sperm cryopreservation protocols in ovine species. These molecules have been widely employed in different mammalian species with this purpose. It is important to consider the existence of a species-specific antioxidant effect discarding the extrapolations from other animal species. To corroborate the real effectiveness of these compounds is important to combine two approaches: in vitro sperm quality analyses and in vivo field trials based on fertility. In the first scenario, a multiparametric analyses and novel tests based on spermatozoa redox balance, as the main target of antioxidants, could improve the accuracy on antioxidant effectiveness on sperm quality. Moreover, an extensive field insemination study provides the definitive tool to select the best antioxidant treatment. All these aspects have been applied and extensively discussed throughout this manuscript. Novel approaches have been incorporated, such as RedoxSYS, to provide more accuracy in the integrative studies of Redox status in spermatozoa. The effectiveness of an antioxidant treatment, as trolox in our study, should be demonstrated in an integrative way, from in vivo (fertility trials) to in vitro analyses (sperm quality assays), especially when the final aim is to reach AI implementation.

Abstract

The optimization of sperm cryopreservation protocols in ram is a feasible tool to reinforce artificial insemination technologies considering the desirable application of sperm by vaginal/cervical or transcervical deposition. Cryopreservation provokes different types of damage on spermatozoa and many of these detrimental effects are triggered by redox deregulation. For this reason, the antioxidant supplementation in sperm cryopreservation protocols to decrease reactive oxygen species (ROS) levels and to equilibrate redox status has been widely employed in different species. Despite this, more fertility trials are necessary to provide the definitive tool to ensure the antioxidant effectiveness on sperm quality. For this reason, in this work, we performed a multiparametric analysis of some previously tested antioxidants (crocin, GSH and Trolox) on ram sperm cryopreservation from field trials to sperm quality analyses focused on new strategies to measure redox balance. Attending to fertility trial, Trolox supplementation registered an improvement concerning to fertility (when we considered high fertility males) and multiple lambing frequency and other complementary and descriptive data related to lambing performance such as prolificacy and fecundity. This positive effect was more evident in multiple lambing frequency when we considered low fertility males than in global male analysis. In vitro analyses of sperm quality confirmed in vivo trials registering a positive effect on sperm viability and redox balance. In this study, we provided the definitive evidence that the role of trolox on redox balance maintenance has a direct effect on fertility parameters, such as prolificacy. The effectiveness of antioxidant treatments was tested, for the first time in ovine species, using an integrative and multiparametric approach combining in vivo and in vitro analyses and novel approaches, such as RedoxSYS. These types of strategies should be applied to improve sperm conservation methods and optimize AI technologies upgrading the correlation between in vitro and in vivo analyses.

SG1002 and Catenated Divalent Organic Sulfur Compounds as Promising Hydrogen Sulfide Prodrugs

Significance: Sulfur has a critical role in protein structure/function and redox status/signaling in all living organisms. Although hydrogen sulfide (H2S) and sulfane sulfur (SS) are now recognized as central players in physiology and pathophysiology, the full scope and depth of sulfur metabolome's impact on human health and healthy longevity has been vastly underestimated and is only starting to be grasped. Since many pathological conditions have been related to abnormally low levels of H2S/SS in blood and/or tissues, and are amenable to treatment by H2S supplementation, development of safe and efficacious H2S donors deserves to be undertaken with a sense of urgency; these prodrugs also hold the promise of becoming widely used for disease prevention and as antiaging agents. Recent Advances: Supramolecular tuning of the properties of well-known molecules comprising chains of sulfur atoms (diallyl trisulfide [DATS], S8) was shown to lead to improved donors such as DATS-loaded polymeric nanoparticles and SG1002. Encouraging results in animal models have been obtained with SG1002 in heart failure, atherosclerosis, ischemic damage, and Duchenne muscular dystrophy; with TC-2153 in Alzheimer's disease, schizophrenia, age-related memory decline, fragile X syndrome, and cocaine addiction; and with DATS in brain, colon, gastric, and breast cancer. Critical Issues: Mode-of-action studies on allyl polysulfides, benzyl polysulfides, ajoene, and 12 ring-substituted organic disulfides and thiosulfonates led several groups of researchers to conclude that the anticancer effect of these compounds is not mediated by H2S and is only modulated by reactive oxygen species, and that their central model of action is selective protein S-thiolation. Future Directions: SG1002 is likely to emerge as the H2S donor of choice for acquiring knowledge on this gasotransmitter's effects in animal models, on account of its unique ability to efficiently generate H2S without byproducts and in a slow and sustained mode that is dose independent and enzyme independent. Efficient tuning of H2S donation characteristics of DATS, dibenzyl trisulfide, and other hydrophobic H2S prodrugs for both oral and parenteral administration will be achieved not only by conventional structural modification of a lead molecule but also through the new "supramolecular tuning" paradigm.

Perfluorooctane Sulfonate (PFOS) and Perfluorohexane Sulfonate (PFHxS) Alters Protein Phosphorylation, Increase ROS Levels and DNA Fragmentation during In Vitro Capacitation of Boar Spermatozoa

Simple Summary

Perfluorinated compounds are synthetic chemicals, with a wide variety of applications like firefighting foams, food packaging, additives in paper and fabrics to avoid dyes. Perfluorooctane sulfonate and perfluorohexane sulfonate are globally distributed, and contaminates air, water, food, and dust, have toxic effects and bioaccumulate. Significant levels of these compounds have found in blood serum, breast milk, and semen of occupationally exposed and unexposed people, as well as in blood serum and organs of the domestic, farm, and wild animals. The present study seeks to analyze the toxic effects and possible alterations caused by the presence of these compounds in boar sperm during the in vitro capacitation, due to their toxicity, worldwide distribution, and lack of information in spermatozoa physiology during pre-fertilization processes.

Abstract

Perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) are toxic and bioaccumulative, included in the Stockholm Convention’s list as persistent organic pollutants. Due to their toxicity, worldwide distribution, and lack of information in spermatozoa physiology during pre-fertilization processes, the present study seeks to analyze the toxic effects and possible alterations caused by the presence of these compounds in boar sperm during the in vitro capacitation. The spermatozoa capacitation was performed in supplemented TALP-Hepes media and mean lethal concentration values of 460.55 μM for PFOS, and 1930.60 μM for PFHxS were obtained. Results by chlortetracycline staining showed that intracellular Ca²⁺ patterns bound to membrane proteins were scarcely affected by PFOS. The spontaneous acrosome reaction determined by FITC-PNA was significantly reduced by PFOS and slightly increased by PFHxS. Both toxic compounds significantly alter the normal capacitation process from 30 min of exposure. An increase in ROS production was observed by flow cytometry and considerable DNA fragmentation by the comet assay. The immunocytochemistry showed a decrease of tyrosine phosphorylation in proteins of the equatorial and acrosomal zone of the spermatozoa head. In conclusion, PFOS and PFHxS have toxic effects on the sperm, causing mortality and altering vital parameters for proper sperm capacitation.

The Impact of Di-2-Ethylhexyl Phthalate on Sperm Fertility

A growing number of studies point to reduced fertility upon chronic exposure to endocrine-disrupting chemicals (EDCs) such as phthalates and plasticizers. These toxins are ubiquitous and are often found in food and beverage containers, medical devices, as well as in common household and personal care items. Animal studies with EDCs, such as phthalates and bisphenol A have shown a dose-dependent decrease in fertility and embryo toxicity upon chronic exposure. However, limited research has been conducted on the acute effects of these EDCs on male fertility. Here we used a murine model to test the acute effects of four ubiquitous environmental toxins: bisphenol A (BPA), di-2-ethylhexyl phthalate (DEHP), diethyl phthalate (DEP), and dimethyl phthalate (DMP) on sperm fertilizing ability and pre-implantation embryo development. The most potent of these toxins, di-2-ethylhexyl phthalate (DEHP), was further evaluated for its effect on sperm ion channel activity, capacitation status, acrosome reaction and generation of reactive oxygen species (ROS). DEHP demonstrated a profound hazardous effect on sperm fertility by producing an altered capacitation profile, impairing the acrosome reaction, and, interestingly, also increasing ROS production. These results indicate that in addition to its known chronic impact on reproductive potential, DEHP also imposes acute and profound damage to spermatozoa, and thus, represents a significant risk to male fertility.

Empiric therapy for idiopathic oligoasthenoteratozoospermia

Male infertility accounts for 50% of the causes of infertile couples, being more than 30% of unknown etiology. In these cases, empiric treatment can be an option prior to the application of assisted reproduction techniques. Empiric treatment can be categorized as hormonal, such as gonadotropins, antiestrogens and aromatase inhibitors, and antioxidant, with vitamins, trace elements and carnitine, among others. Although scientifically acceptable evidence is limited due to the absence of large randomized and controlled clinical trials, recent systematic reviews and meta-analyses show that treatment with gonadotropins, antiestrogens and antioxidants increases pregnancy and live birth rates and improves seminal parameters. Empiric medical treatment for idiopathic infertility can be considered in specific cases in order to improve semen quality and spontaneous fertility.

Sperm cryostorage in a dry tank: An accurate alternative

This prospective study aimed to determine the effects of dry nitrogen cryostorage on human sperm characteristics in comparison with liquid nitrogen cryostorage. For this purpose, 42 men undergoing routine semen analysis (21 normozoospermia and 21 with altered semen parameters) were analyzed. After slow freezing, half of the straws of each sample were randomly stored in liquid and dry tanks, at the top and bottom levels of the latter. After 6 months storage, thawed samples were treated by density gradient centrifugation and sperm characteristics were compared. There was no difference in sperm progressive motility (15.1% ± 14.2% vs. 15.1% ± 12.7%; p = 0.76), sperm vitality (25.5% ± 17.7% vs. 26.2% ± 19%; p = 0.71), percentages of acrosome-reacted spermatozoa (38% ± 8.5% vs. 38.5% ± 7.4%; p = 0.53) and DNA fragmentation spermatozoa (27.3% ± 12.4% vs. 28.5% ± 12.9%, p = 0.47) after cryostorage in the dry or the liquid nitrogen tank. Moreover, we did not observe differences between either cryostorage system for normal and altered sperm samples. This lack of difference was also observed whatever the floor level of cryostorage in the dry tank. The temperature measurement of the dry tank showed a stable temperature at -194 °C throughout storage whatever the storage floor level, guaranteeing the stability of the low temperatures suitable for human sperm storage. Because of its greater safety, dry storage without contact with the liquid phase should be preferred and can be a useful alternative for the cryostorage of human sperm samples.

Large-scale mtDNA deletions as genetic biomarkers for susceptibility to male infertility: A systematic review and meta-analysis

Several complex rearrangements such as deletions in mitochondrial DNA (mtDNA) have been identified in sperm deficiencies. This study aimed to investigate the association of common mtDNA deletions with male infertility using a meta-analysis approach. Standard databases were systematically searched to discover relevant studies. Pooled odds ratios (ORs) with corresponding 95% confidence intervals (CI) were estimated to analyze the association of mtDNA deletions with male infertility. Our data revealed a significant association between a common 4977-bp deletion and an increased risk of male infertility. A similar association was observed in an Asian population. Stratified analysis by infertility phenotype showed significant associations between the 4977-bp deletion and increased risk of asthenozoospermia, oligoasthenoteratozoospermia, and asthenoteratozoospermia. In addition, significant associations were found in studies with sample sizes >100, age of participants <45 years, subject selection according to WHO criteria, and studies of moderate to high quality. Regarding the other common mtDNA deletions, significant associations were observed between 7436-bp, 7599-bp, and 4866-bp deletions and the risk of male infertility. Our findings suggest that the 4977-bp deletion might be a risk factor for male infertility, especially in an ethnic and infertility phenotype dependent manner.

Loss of flavin adenine dinucleotide (FAD) impairs sperm function and male reproductive advantage in C. elegans

Exposure to environmental stress is clinically established to influence male reproductive health, but the impact of normal cellular metabolism on sperm quality is less well-defined. Here we show that impaired mitochondrial proline catabolism, reduces energy-storing flavin adenine dinucleotide (FAD) levels, alters mitochondrial dynamics toward fusion, and leads to age-related loss of sperm quality (size and activity), which diminishes competitive fitness of the animal. Loss of the 1-pyrroline-5-carboxylate dehydrogenase enzyme alh-6 that catalyzes the second step in mitochondrial proline catabolism leads to premature male reproductive senescence. Reducing the expression of the proline catabolism enzyme alh-6 or FAD biosynthesis pathway genes in the germline is sufficient to recapitulate the sperm-related phenotypes observed in alh-6 loss-of-function mutants. These sperm-specific defects are suppressed by feeding diets that restore FAD levels. Our results define a cell autonomous role for mitochondrial proline catabolism and FAD homeostasis on sperm function and specify strategies to pharmacologically reverse these defects.

Molecular Changes Induced by Oxidative Stress that Impair Human Sperm Motility

A state of oxidative stress (OS) and the presence of reactive oxygen species (ROS) in the male reproductive tract are strongly correlated with infertility. While physiological levels of ROS are necessary for normal sperm functioning, elevated ROS production can overwhelm the cell's limited antioxidant defenses leading to dysfunction and loss of fertilizing potential. Among the deleterious pleiotropic impacts arising from OS, sperm motility appears to be particularly vulnerable. Here, we present a mechanistic account for how OS contributes to altered sperm motility profiles. In our model, it is suggested that the abundant polyunsaturated fatty acids (PUFAs) residing in the sperm membrane serve to sensitize the male germ cell to ROS attack by virtue of their ability to act as substrates for lipid peroxidation (LPO) cascades. Upon initiation, LPO leads to dramatic remodeling of the composition and biophysical properties of sperm membranes and, in the case of the mitochondria, this manifests in a dissipation of membrane potential, electron leakage, increased ROS production and reduced capacity for energy production. This situation is exacerbated by the production of cytotoxic LPO byproducts such as 4-hydroxynonenal, which dysregulate molecules associated with sperm bioenergetic pathways as well as the structural and signaling components of the motility apparatus. The impact of ROS also extends to lesions in the paternal genome, as is commonly seen in the defective spermatozoa of asthenozoospermic males. Concluding, the presence of OS in the male reproductive tract is strongly and positively correlated with reduced sperm motility and fertilizing potential, thus providing a rational target for the development of new therapeutic interventions.

Supplementation of green tea extract (GTE) in extender improves structural and functional characteristics, total antioxidant capacity and in vivo fertility of buffalo (Bubalus bubalis) bull spermatozoa

The aim of this study was to elucidate the beneficial effects of green tea extract (GTE) in tris citric acid extender on post thaw structural and functional characteristics, DNA fragmentation (%), total antioxidant capacity (TAC, μM/L), lipid peroxidation (LPO, μM/mL) levels and in vivo fertility of buffalo (Bubalus bubalis) bull spermatozoa. GTE is a acknowledged natural antioxidant, act as a free radical scavenger and protects spermatozoa against oxidative stress. Three mature and donor buffalo bulls were used in this experiment. Two ejaculates were collected per bull on each collection day, followed by initial evaluation for consistency (colour), volume (mL), progressive motility and concentration (x10⁹) and were diluted in five extenders @ 50 x 10⁶/ mL (C = control, no GTE; T1 = treatment 1, GTE 0.1%; T2 = treatment 2, GTE 0.5%; T3 = treatment 3, GTE 0.75% and T4 = treatment 4, GTE1.0%). The experiment was repeated thrice. Data analysis showed that sperm progressive motility (%), plasma membrane integrity (%), supravital plasma membrane integrity (%), viable sperm with intact acrosome (%) and TAC were significantly higher (P < 0.05) in extender supplemented with T4 as compared to control. Furthermore, sperm DNA fragmentation and occurrance of LPO in buffalo bull spermatozoa were significantly lowered in T4 than control. In vitro longevity (%) of spermatozoa was significantly higher in T4 compared to control during 45 and 90 min of incubation at 37 °C. In vivo fertility rate of buffalo bull spermatozoa was significantly higher in T4 compared to control (64.96 vs. 48.40%, P < 0.05). It is concluded that supplementation of tris citric acid extender with 1.0% GTE improved structural and functional characteristics, TAC, in vitro longevity (%) and in vivo fertility, whereas decreased DNA fragmentation and LPO occurrence in buffalo bull spermatozoa after freezing and thawing protocol.

The association of seminal leucocytes, interleukin-6 and interleukin-8 with sperm DNA fragmentation: A prospective study

The effect of seminal leucocytes on sperm DNA integrity has been discussed controversially in literatures. Moreover, the studies investigating the in vivo effect of pro-inflammatory cytokines interleukin-6 and interleukin-8 on sperm DNA fragmentation are scarce and inconsistent. The association of standard sperm parameters with sperm DNA fragmentation is also a matter of ongoing discussion. Hence, the aims of this study were, first, to evaluate the effect of seminal leucocytes, interleukin-6 and interleukin-8 on sperm DNA integrity and, second, to examine whether standard semen parameters are associated with sperm DNA fragmentation. Seminal leucocytes, interleukin-6, interleukin-8 and standard semen parameters, including total sperm number, sperm concentration, progressive motility, nonprogressive motility, immotility and normal morphology, were determined in 134 consecutive men. The concentrations of seminal leucocytes, interleukin-6 and interleukin-8, did not correlate with sperm DNA fragmentation. In contrast, total sperm number, sperm concentration, progressive motility, nonprogressive motility and normal morphology exhibited significant inverse correlations with sperm DNA fragmentation. Immotile spermatozoa were directly correlated with sperm DNA fragmentation. In conclusion, seminal leucocytes, interleukin-6 and interleukin-8, are not associated with sperm DNA fragmentation. Poor standard semen parameters are significantly related to the high levels of sperm DNA fragmentation.

Diurnal variation in sperm DNA fragmentation: analysis of 11,382 semen samples from two populations and in vivo animal experiments

Circadian rhythms have been found in some reproductive functions phenotypes but remain unclear for sperm DNA fragmentation index (DFI). The present study aims to investigate the diurnal variation of DFI in mice model and men sperm. Adult male mice were sacrificed for sperm DFI with Sperm Chromatin Structure Assay (SCSA) in 24 hours at 6 evenly distributed time points. A cosinor pattern of DFI was observed with a nadir at zeitgeber time 10 AM. In a community population with 630 semen samples collected between 8 AM and 20 PM, the temporal variation of DFI also fit a cosinor pattern with a - 343° acrophase and a nadir at 11 AM (P = .031). In a reproductive-medical-center dataset of 10752 semen samples collected between 7 AM and 11 AM, the decreasing trend of DFI was also confirmed. For the males with multiple samples, intra-individual comparison between different timepoints was performed, and each consecutive hour after 7 AM was also associated with 2.5 (95% CI: -1.0, 5.9)% lower DFI by SCSA or 4.9 (1.9, 7.8)% lower DFI by SCD. Our study reveals a daily diurnal variance in sperm DFI which may suggest a practical approach to get more qualified sperms for natural or assisted reproduction. Abbreviations: BMI, Body mass index; DFI, DNA fragmentation index; MARHCS, Male Reproductive Health in the Chongqing College Students; RMC, Reproductive Medical Center; SCD, Sperm Chromatin Dispersion; SCSA, Sperm Chromatin Structure Assay.

Antioxidant and anti-apoptotic effects of royal jelly against nicotine-induced testicular injury in mice

This study describes the effects of royal jelly (RJ) on testicular injury induced by nicotine (NIC) in mice. Thirty-six male BALB/c mice were randomly divided into six groups (n = 6). Group 1 received normal saline, group 2 received 100 mg/kgBW/day RJ, groups 3 and 4 received NIC at doses of 0.50 and 1.00 mg/kgBW/day, respectively, and groups 5 and 6 received NIC at doses of 0.50 and 1.00 mg/kg BW/day, respectively, plus RJ. Following 35 days, the serum level of testosterone, histopathological changes, germ cell apoptosis, proliferating cell nuclear antigen (PCNA), malondialdehyde (MDA) content, and antioxidant indexes including total antioxidant capacity (TAC) and catalase (CAT) activity were determined. In addition, the mitochondria-dependent apoptosis was investigated by assessing the Bcl-2, p53, and Caspase-3 mRNA levels expression by reverse transcription-PCR (RT-PCR). Compared to NIC receiving groups, the concomitant administration of RJ could protect the testosterone reduction and histological damages. After RJ treatment, the level of tissue MDA content decreased, while tissue TAC and CAT levels were remarkably increased compared to NIC-exposed groups. Remarkable higher TUNEL-positive germ cells and low PCNA index were observed in NIC receiving groups. Besides, the expression level of Bcl-2 was significantly higher and the p53 and Caspase-3 levels were significantly lower in the RJ co-administration groups than NIC-only receiving groups. Our results confirmed that RJ effectively protects the testis against NIC evoked damages by antioxidant and anti-apoptotic effects involving the up regulation of the antioxidant status, mitochondria-dependent apoptosis pathway prevention, and the proliferating activity improvement.

Antioxidant enzyme expression of mRNA and protein in the epididymis of finasteride-treated male rat offspring during postnatal development

INTRODUCTION

We verify whether finasteride had a transgenerational effect on the epididymal expression of antioxidant enzymes, and the correlation between these enzymes and blood androgen concentrations in male offspring (F1:Fin) of females fertilized by finasteride-treated male rats.

MATERIAL AND METHODS

The expression of CAT, SOD1, GPX5, GR on the mRNA and protein levels was evaluated in the epididymis at postnatal day (PND) 7, 14, 21, 28 and 90. Levels of T and DHT were correlated with mRNA levels of enzymes by Spearman's rank correlation coefficient.

RESULTS

A change in the levels of transcripts was noted in F1:Fin rats: CAT decreased at PND 28 (p < 0.01) and increased at PND 90 (p < 0.01); SOD1 increased at PND 7 (p < 0.0001), 21 (p < 0.001), 90 (p < 0.0001) and decreased at 14 PND (p < 0.01); GPX5 increased at PND 14 and 21 (p < 0.0001); GR decreased at PND 21 and 28 (p < 0.0001). Altered immunolocalization of enzymes within the epididymal epithelium was observed. Negative correlations between GPX5 mRNA with androgens (T, p = 0.0002; DHT, p = 0.0009) were visible in the control rats, and positive correlation between DHT and CAT mRNA (p = 0.03), in opposite to F1:Fin group were was negative for both androgens (T, p = 0.044 and DHT, p = 0.02).

CONCLUSIONS

Finasteride treatment of adult male rats may cause changes in antioxidant defense system in the epididymis of their offspring, leading to improper ROS concentrations that can affect post-testicular sperm maturation.

The progesterone-induced sperm acrosome reaction is a good option for the prediction of fertilization in vitro compared with other sperm parameters

Progesterone (P₄ ) is crucial for the physiological function of spermatozoa. In the study, we investigated the correlation between P₄ -induced sperm acrosome reaction (AR) and parameters including sperm progressive motility, normal morphology and sperm DNA fragmentation (SDF), and compared the in vitro fertilization (IVF) predictive values of these indicators based on the multivariate regressions analysis and receiver operator characteristics (ROC) curve analyses. The results demonstrated a negative correlation between P₄ -induced sperm AR and the SDF, with the correlation -9.05 (-17.25 to -0.84), p<0.05, n = 47). No relationship was found between the sperm progressive motility, normal morphology and the induced AR. The P₄ -induced AR and SDF were both significantly correlated to the fertilization rate. ROC curve analyses indicated that P₄ -induced AR was a better prognostic predictor for the fertilization rate compared with the SDF, with the areas under the curve 0.729 (0.580-0.849), p<0.01 and 0.637 (0.484-0.772), p=0.16 respectively. The cut-off value for P₄ -induced AR to predict "50% fertilization rate" was 23.4% with sensitivity and specificity of 63.3% and 88.2% respectively. The overall results indicated that the assessment of P₄ -induced AR seemed to be a more sensitive indicator for fertilization rate in vitro compared with other sperm parameters.