Role of oxidative stress in male infertility

Assessing the efficacy of a novel sperm-washing medium enriched with serotonin, L-carnitine, and coenzyme Q10: an observational cohort study

ABSTRACT

This observational cohort study investigated the potential of a novel sperm-washing medium (SWM) enriched with serotonin (5-HT), L-carnitine (L-C), and coenzyme Q10 (CoQ10) to enhance sperm motility and reduce DNA damage. It compared this innovative medium (5-HT/L-C/CoQ10 SWM) with two widely used commercial media (SWM 1 and SWM 2). Ninety-eight volunteers from an infertility clinic provided semen samples, which were divided into three aliquots for analysis in different SWMs: group 1, SWM was composed of hydroxyethyl piperazineethanesulfonic acid (HEPES), sodium bicarbonate, human serum albumin (HSA), taurine, and gentamicin sulfate (SWM 1); group 2, SWM was composed of HEPES, sodium bicarbonate, and HSA (SWM 2); and group 3, SWM was composed of HEPES-buffered human tubal fluid supplemented with 5-HT, L-C, and CoQ10 (5-HT/L-C/CoQ10 SWM). Sperm motility was categorized as progressive, nonprogressive, or immotile. Apoptosis, reactive oxygen species (ROS) production, and DNA fragmentation were also assessed. There were no significant differences in total or progressive sperm motility among the groups. Spermatozoa in group 3 exhibited reduced apoptosis, necrosis, and ROS levels and increased viability. No significant differences were observed in the DNA fragmentation index among groups. The 5-HT/L-C/CoQ10 SWM reduced sperm oxidative stress and apoptosis compared with those of the two commercially available SWMs, suggesting that 5-HT/L-C/CoQ10 SWM could be useful for enhancing in vitro fertilization success rates.

Maternal supplementation of alpha-lipoic acid ameliorates prenatal cytarabine-induced mutilation in reproductive development and function in F1 male adult rats

AIMS

Cytarabine (CYT), a prevalent anticancer drug for blood cancers, detrimentally affects male reproductive development and function. Alpha-lipoic acid (ALA), a universal antioxidant, offers defense against chemical-induced reproductive dysfunction. Our study sought to explore ALA's protective role against prenatal CYT-induced reproductive impairment in F1 male adult rats.

MAIN METHODS

Pregnant rats were divided into 5 groups and administered normal saline, ALA 200 mg/kg, CYT 12.5 mg/kg, CYT 25 mg/kg, and CYT 25 mg/kg + ALA 200 mg/ kg from gestational day 8 to 21. On postnatal day 73, F1 male rats were sacrificed, and general, oxidative, steroidogenic, spermatogenic, histological, and morphometrical parameters were evaluated.

KEY FINDINGS

Prenatal CYT caused dose-dependent reductions in body weight, testis, and accessory gland weights; elevated oxidative stress; delayed puberty onset; sperm anomalies (decreased count, motility, viability, seminal fructose; increased morphological anomalies); impeded steroidogenesis (lower testosterone, follicle-stimulating hormone, luteinizing hormone, 3β-Hydroxysteroid dehydrogenase(HSD), 17β-HSD, and elevated cholesterol); and testicular histopathological and morphometric disturbances. Maternal supplementation of ALA was found to alleviate all the CYT-induced reproductive disruptions.

SIGNIFICANCE

The present work accentuates the beneficial actions of ALA against CYT-induced impairment in reproductive development and functions by combating disruptions in oxidative balance, steroidogenesis, spermatogenesis, and testicular histological aberrations. However, future experimental and clinical studies are warranted to explore the molecular mechanisms involved in the ALA's protection against prenatal CYT-induced testicular injury.

Decrease in Sperm Parameters in the 21st Century: Obesity, Lifestyle, or Environmental Factors? An Updated Narrative Review

Semen quality represents a compelling factor for fertility, and delineating the normal values has proven difficult. In the last four decades, several authors have reported a noticeable decline in sperm parameters. Also, studies investigating 'time to pregnancy' have shown that fecundity begins to be reduced when sperm numbers decrease below 30 million, even though according to the 6th edition of the WHO manual, the normal value is currently 16 million/mL or 39 million per ejaculate. There exists sufficient data to suggest a decline in sperm counts over time, even though the clear reason for this adverse trend is not well established, but some associations have been hypothesised, such as maternal smoking during pregnancy. Additional potential factors have yet to be fully illustrated but involve poor diet, increased obesity, and exposure to environmental toxins. Moreover, the change in environmental conditions and more common exposure to endocrine-disrupting chemicals (EDCs), such as pesticides and herbicides, as well as bisphenol A, phthalates, polychlorinated biphenyls, and heavy metals, starting from prenatal life and continuing into adulthood, may exhibit probable features explaining the reduction in sperm parameters. Therefore, the main goal of this narrative review is to furnish an overview of the possible effects of exposure to EDCs on testicular function and spermatogenesis and, also, to summarise the evidence regarding a decrease in sperm quality and examine its potential consequences.

Redox Homeostasis and Nrf2-Regulated Mechanisms Are Relevant to Male Infertility

Infertility represents a significant global health challenge, affecting more than 12% of couples worldwide, and most cases of infertility are caused by male factors. Several pathological pathways are implicated in male infertility. The main mechanisms involved are driven by the loss of reduction-oxidation (redox) homeostasis and the resulting oxidative damage as well as the chronic inflammatory process. Increased or severe oxidative stress leads to sperm plasma membrane and DNA oxidative damage, dysregulated RNA processing, and telomere destruction. The signaling pathways of these molecular events are also regulated by Nuclear factor-E2-related factor 2 (Nrf2). The causes of male infertility, the role of oxidative stress in male infertility and the Keap1-Nrf2 antioxidant pathway are reviewed. This review highlights the regulatory role of Nrf2 in the balance between oxidants and antioxidants as relevant mechanisms to male fertility. Nrf2 is involved in the regulation of spermatogenesis and sperm quality. Establishing a link between Nrf2 signaling pathways and the regulation of male fertility provides the basis for molecular modulation of inflammatory processes, reactive oxygen species generation, and the antioxidant molecular network, including the Nrf2-regulated antioxidant response, to improve male reproductive outcomes.

Optimum Doses and Forms of Selenium Maintaining Reproductive Health via Regulating Homeostasis of Gut Microbiota and Testicular Redox, Inflammation, Cell Proliferation, and Apoptosis in Roosters

BACKGROUND

There is a U-shaped relationship between dietary selenium (Se) ingestion and optimal sperm quality.

OBJECTIVES

This study aimed to investigate the optimal dietary dose and forms of Se for sperm quality of breeder roosters and the relevant mechanisms.

METHODS

In experiment 1, 18-wk-old Jingbai laying breeder roosters were fed a Se-deficient base diet (BD, 0.06 mg Se/kg), or the BD + 0.1, 0.2, 0.3, 0.4, 0.5, or 1.0 mg Se/kg for 9 wk. In experiment 2, the roosters were fed the BD or the BD + sodium selenite (SeNa), seleno-yeast (SeY), or Se-nanoparticles (SeNPs) at 0.2 mg Se/kg for 9 wk.

RESULTS

In experiment 1, added dietary 0.2 and 0.3 mg Se/kg led to higher sperm motility and lower sperm mortality than the other groups at weeks 5, 7, and/or 9. Furthermore, added dietary 0.2-0.4 mg Se/kg produced better testicular histology and/or lower testicular 8-hydroxy-deoxyguanosine than the other groups. Moreover, integrated testicular transcriptomic and cecal microbiomic analysis revealed that inflammation, cell proliferation, and apoptosis-related genes and bacteria were dysregulated by Se deficiency or excess. In experiment 2, compared with SeNa, SeNPs slightly increased sperm motility throughout the experiment, whereas SeNPs slightly reduced sperm mortality compared with SeY at week 9. Both SeY and SeNPs decreased malondialdehyde in the serum than those of SeNa, and SeNPs led to higher glutathione peroxidase (GPX) and thioredoxin reductase activities and GPX1 and B-cell lymphoma 2 protein concentrations in the testis compared with SeY and SeNa.

CONCLUSIONS

The optimal dietary Se dose for reproductive health of breeder roosters is 0.25-0.35 mg Se/kg, and SeNPs displayed better effects on reproductive health than SeNa and SeY in laying breeder roosters. The optimal doses and forms of Se maintain reproductive health of roosters associated with regulation intestinal microbiota homeostasis and/or testicular redox balance, inflammation, cell proliferation, and apoptosis.

Male Reproductive Toxicity of Antifouling Chemicals: Insights into Oxidative Stress-Induced Infertility and Molecular Mechanisms of Zinc Pyrithione (ZPT)

Zinc pyrithione (ZPT), a widely utilized industrial chemical, is recognized for its versatile properties, including antimicrobial, antibacterial, antifungal, and antifouling activities. Despite its widespread use, recent research has shed light on its toxicity, particularly towards the male reproductive system. While investigations into ZPT's impact on male reproduction have been conducted, most of the attention has been directed towards marine organisms. Notably, ZPT has been identified as a catalyst for oxidative stress, contributing to various indicators of male infertility, such as a reduced sperm count, impaired sperm motility, diminished testosterone levels, apoptosis, and degenerative changes in the testicular tissue. Furthermore, discussions surrounding ZPT's effects on DNA and cellular structures have emerged. Despite the abundance of information regarding reproductive toxicity, the molecular mechanisms underlying ZPT's detrimental effects on the male reproductive system remain poorly understood. This review focuses specifically on ZPT, delving into its reported toxicity on male reproduction, while also addressing the broader context by discussing other antifouling chemicals, and emphasizing the need for further exploration into its molecular mechanisms.

Human Papillomavirus and Male Infertility: What Do We Know?

In recent years, increasing attention has been paid to understanding the causes of infertility, which is being recognized as a growing health problem affecting large numbers of couples worldwide. Male infertility is a contributing factor in approximately 30-40% of cases, and one of its etiological causes is sexually transmitted infections (STIs). Among sexually transmitted pathogens, human papillomavirus (HPV) can contribute in various ways to the failure of spontaneous and assisted reproduction, acting in the different phases of conception, especially in the early ones. In particular, HPV infection can affect sperm DNA integrity, sperm motility, count, viability, and morphology and can induce the production of anti-sperm antibodies (ASAs). In this narrative review, we aimed to provide an overview of existing research on the potential adverse effects of HPV infection on male reproductive health. Furthermore, we analyzed how limiting the spread of the infection, particularly with gender-neutral vaccination, could be a possible therapeutic tool to counteract male and female fertility problems.

Spermatogenesis recovery treatment in less than four months from zero to almost 16 million sperms per milliliter after several cycles of steroids in 44-year-old healthy man

The most common external factors that men can have influence on, and improve its own spermatogenesis, are related to lifestyle, habits, stress level, sport activities, nutrition quality, and medications. Steroids became one of the key issues in young men during reproductive stage of life. More and more teenagers who are not even developed yet naturally start using supplements very early to build up body and strengths of muscles in the shortest possible time. In this report is presented the case of 44-year-old (November 2022), healthy, and sporty man, who is 1-2 times per year on steroid cycles since he turned 40th. He had intention to become a father; however after 6 months of the last steroid cycle, sperm count was zero. This case will show what was needed and successfully done within less than 4 months after last steroids administration and the moment when sperm count reached almost 16 million sperms per milliliter. However, it has to be clear that this is unique case and additional tests would be needed on bigger population to confirm fast post steroid sperm count recovery in healthy subjects, using approach from this manuscript.

Captivating Colors, Crucial Roles: Astaxanthin's Antioxidant Impact on Fish Oxidative Stress and Reproductive Performance

Fish, constantly exposed to environmental stressors due to their aquatic habitat and high metabolic rates, are susceptible to oxidative stress. This review examines the interplay between oxidative stress and fish reproduction, emphasizing the potent antioxidant properties of astaxanthin. Our primary objective is to highlight astaxanthin's role in mitigating oxidative stress during critical reproductive stages, leading to improved gamete quality, ovary development, and hormone levels. We also explore its practical applications in aquaculture, including enhanced pigmentation and overall fish health. We conducted a comprehensive literature review, analyzing studies on astaxanthin's antioxidant properties and its impact on fish reproduction. Astaxanthin, a carotenoid pigment, effectively combats reactive oxygen species, inhibiting lipid peroxidation and maintaining membrane integrity. It significantly enhances reproductive success in fish and improves overall fish health in aquaculture settings. This review reveals astaxanthin's multifaceted benefits in fish health and reproduction, offering economic advantages in aquaculture. Future research should delve into species-specific responses, optimal dosages, and the long-term effects of astaxanthin supplementation to inform sustainable aquaculture strategies.