Effects of N-acetylcysteine on Semen Parameters and Oxidative/Antioxidant Status

Antioxidants for male subfertility

BACKGROUND

The inability to have children affects 10% to 15% of couples worldwide. A male factor is estimated to account for up to half of the infertility cases with between 25% to 87% of male subfertility considered to be due to the effect of oxidative stress. Oral supplementation with antioxidants is thought to improve sperm quality by reducing oxidative damage. Antioxidants are widely available and inexpensive when compared to other fertility treatments, however most antioxidants are uncontrolled by regulation and the evidence for their effectiveness is uncertain. We compared the benefits and risks of different antioxidants used for male subfertility. This review did not examine the use of antioxidants in normospermic men.

OBJECTIVES

To evaluate the effectiveness and safety of supplementary oral antioxidants in subfertile men.

SEARCH METHODS

The Cochrane Gynaecology and Fertility (CGF) Group trials register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, and two trials registers were searched on 1 February 2018, together with reference checking and contact with study authors and experts in the field to identify additional trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared any type, dose or combination of oral antioxidant supplement with placebo, no treatment or treatment with another antioxidant, among subfertile men of a couple attending a reproductive clinic. We excluded studies comparing antioxidants with fertility drugs alone and studies that included fertile men attending a fertility clinic because of female partner infertility.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. The primary review outcome was live birth. Clinical pregnancy, adverse events and sperm parameters were secondary outcomes.

MAIN RESULTS

We included 61 studies with a total population of 6264 subfertile men, aged between 18 and 65 years, part of a couple who had been referred to a fertility clinic and some of whom were undergoing assisted reproductive techniques (ART). Investigators compared and combined 18 different oral antioxidants. The evidence was of 'low' to 'very low' quality: the main limitation was that out of the 44 included studies in the meta-analysis only 12 studies reported on live birth or clinical pregnancy. The evidence is current up to February 2018.Live birth: antioxidants may lead to increased live birth rates (OR 1.79, 95% CI 1.20 to 2.67, P = 0.005, 7 RCTs, 750 men, I2 = 40%, low-quality evidence). Results suggest that if in the studies contributing to the analysis of live birth rate, the baseline chance of live birth following placebo or no treatment is assumed to be 12%, the chance following the use of antioxidants is estimated to be between 14% and 26%. However, this result was based on only 124 live births from 750 couples in seven relatively small studies. When studies at high risk of bias were removed from the analysis, there was no evidence of increased live birth (Peto OR 1.38, 95% CI 0.89 to 2.16; participants = 540 men, 5 RCTs, P = 0.15, I2 = 0%).Clinical pregnancy rate: antioxidants may lead to increased clinical pregnancy rates (OR 2.97, 95% CI 1.91 to 4.63, P < 0.0001, 11 RCTs, 786 men, I2 = 0%, low-quality evidence) compared to placebo or no treatment. This suggests that if in the studies contributing to the analysis of clinical pregnancy, the baseline chance of clinical pregnancy following placebo or no treatment is assumed to be 7%, the chance following the use of antioxidants is estimated to be between 12% and 26%. This result was based on 105 clinical pregnancies from 786 couples in 11 small studies.Adverse eventsMiscarriage: only three studies reported on this outcome and the event rate was very low. There was no difference in miscarriage rate between the antioxidant and placebo or no treatment group (OR 1.74, 95% CI 0.40 to 7.60, P = 0.46, 3 RCTs, 247 men, I2 = 0%, very low-quality evidence). The findings suggest that in a population of subfertile men with an expected miscarriage rate of 2%, the chance following the use of an antioxidant would result in the risk of a miscarriage between 1% and 13%.Gastrointestinal: antioxidants may lead to an increase in mild gastrointestinal upsets when compared to placebo or no treatment (OR 2.51, 95% CI 1.25 to 5.03, P = 0.010, 11 RCTs, 948 men, I2 = 50%, very low-quality evidence). This suggests that if the chance of gastrointestinal upsets following placebo or no treatment is assumed to be 2%, the chance following the use of antioxidants is estimated to be between 2% and 9%. However, this result was based on a low event rate of 35 out of 948 men in 10 small or medium-sized studies, and the quality of the evidence was rated very low and was high in heterogeneity.We were unable to draw any conclusions from the antioxidant versus antioxidant comparison as insufficient studies compared the same interventions.

AUTHORS' CONCLUSIONS

In this review, there is low-quality evidence from seven small randomised controlled trials suggesting that antioxidant supplementation in subfertile males may improve live birth rates for couples attending fertility clinics. Low-quality evidence suggests that clinical pregnancy rates may also increase. Overall, there is no evidence of increased risk of miscarriage, however antioxidants may give more mild gastrointestinal upsets but the evidence is of very low quality. Subfertilte couples should be advised that overall, the current evidence is inconclusive based on serious risk of bias due to poor reporting of methods of randomisation, failure to report on the clinical outcomes live birth rate and clinical pregnancy, often unclear or even high attrition, and also imprecision due to often low event rates and small overall sample sizes. Further large well-designed randomised placebo-controlled trials reporting on pregnancy and live births are still required to clarify the exact role of antioxidants.

Effects of N-acetyl-cysteine supplementation on sperm quality, chromatin integrity and level of oxidative stress in infertile men

BACKGROUND

Infertile men have higher levels of semen reactive oxygen species (ROS) than fertile men. High levels of semen ROS can cause sperm dysfunction, sperm DNA damage and reduced male reproductive potential. This study investigated the effects of supplementation with N-acetyl-cysteine (NAC) on the sperm quality, chromatin integrity and levels of oxidative stress in infertile men.

METHODS

The study was carried out in the unit of ACECR Infertility Research Center, Qom, Iran. The patients consisted of 50 infertile men with asthenoteratozoospermia who received NAC (600 mg/d) orally for 3 months, after which they were compared with pre-treatment status. Semen was analyzed according to WHO (2010), followed by the assessment of protamine content [chromomycin A3 (CMA3)] and DNA integrity [terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)]. Oxidative stress markers, i.e. total antioxidant capacity (TAC) and malondialdehyde (MDA), as well as hormonal profile (LH, FSH, Testosterone and Prolactin) were determined by ELISA kit.

RESULTS

After NAC treatment, patients' sperm count and motility increased significantly whereas abnormal morphology, DNA fragmentation and protamine deficiency showed significant decreases compared to pre-treatment levels (P < 0.05). Hormonal profile improvement was associated with lowered FSH and LH levels and increased amount of testosterone (P < 0.05). TAC significantly increased and MDA decreased with an inverse significant correlation between TAC and MDA (P < 0.05).

CONCLUSION

NAC oral supplementation may improve sperm parameters and oxidative/antioxidant status in infertile males.

Protective role of N-acetylcysteine (NAC) on human sperm exposed to etoposide

Background

Although recent progress in cancer treatment has increased patient survival and improved quality of life, reproductive side effects are still for concern. One way to decrease gonadal impairment is to use cytoprotectors. In testicular cancer, etoposide is generally used in combination with other agents, but there are no in-vitro studies of sperm exposure to etoposide and cytoprotectors, namely N-acetylcysteine (NAC).

Methods

Twenty semen samples were individually divided into five groups: control, incubation with NAC alone, incubation with etoposide alone, sequential exposure of NAC followed by etoposide (pre-treatment) and sequential exposure of etoposide followed by NAC (post-treatment). Sperm characteristics, chromatin condensation (aniline blue), DNA fragmentation (TUNEL), oxidative stress (OxyDNA labelling) and glutathione quantification were used to evaluate the capabilities of NAC as a prophylactic (pre-treatment) or ameliorator (post-treatment) agent over the effects caused in sperm during in-vitro exposure to etoposide.

Results

No deleterious effects were observed on sperm motility or sperm membrane integrity. Results revealed that prophylactic use of NAC (pre-treatment) increased rates of immature sperm chromatin as compared to ameliorator use of NAC (post-treatment), and increased rates of sperm DNA fragmentation in relation to controls. Pre and post-treatment with NAC increased oxidative levels in comparison to controls, but also increased levels of cellular antioxidant glutathione.

Conclusions

The results indicate that NAC has the ability to counteract etoposide-induced toxicity rather than preventing the etoposide cytotoxic effects over sperm DNA, suggesting that the administration of NAC to cells formerly exposed to etoposide is preferable to its prophylactic use. As the results evidenced that NAC seems to be more efficient in attenuating sperm etoposide cytotoxic effects instead of being used as a chemoprophylactic agent, this reinforces the idea that there might be a new NAC mechanism over DNA.

Oxidative Stress in the Male Germline: A Review of Novel Strategies to Reduce 4-Hydroxynonenal Production

Germline oxidative stress is intimately linked to several reproductive pathologies including a failure of sperm-egg recognition. The lipid aldehyde 4-hydroxynonenal (4HNE) is particularly damaging to the process of sperm-egg recognition as it compromises the function and the stability of several germline proteins. Considering mature spermatozoa do not have the capacity for de novo protein translation, 4HNE modification of proteins in the mature gametes has uniquely severe consequences for protein homeostasis, cell function and cell survival. In somatic cells, 4HNE overproduction has been attributed to the action of lipoxygenase enzymes that facilitate the oxygenation and degradation of ω-6 polyunsaturated fatty acids (PUFAs). Accordingly, the arachidonate 15-lipoxygenase (ALOX15) enzyme has been intrinsically linked with 4HNE production, and resultant pathophysiology in various complex conditions such as coronary artery disease and multiple sclerosis. While ALOX15 has not been well characterized in germ cells, we postulate that ALOX15 inhibition may pose a new strategy to prevent 4HNE-induced protein modifications in the male germline. In this light, this review focuses on (i) 4HNE-induced protein damage in the male germline and its implications for fertility; and (ii) new methods for the prevention of lipid peroxidation in germ cells.

Ryanodine Receptor 1-Related Myopathies: Diagnostic and Therapeutic Approaches

Ryanodine receptor type 1-related myopathies (RYR1-RM) are the most common class of congenital myopathies. Historically, RYR1-RM classification and diagnosis have been guided by histopathologic findings on muscle biopsy. Main histological subtypes of RYR1-RM include central core disease, multiminicore disease, core-rod myopathy, centronuclear myopathy, and congenital fiber-type disproportion. A range of RYR1-RM clinical phenotypes has also emerged more recently and includes King Denborough syndrome, RYR1 rhabdomyolysis-myalgia syndrome, atypical periodic paralysis, congenital neuromuscular disease with uniform type 1 fibers, and late-onset axial myopathy. This expansion of the RYR1-RM disease spectrum is due, in part, to implementation of next-generation sequencing methods, which include the entire RYR1 coding sequence rather than being restricted to hotspot regions. These methods enhance diagnostic capabilities, especially given historic limitations of histopathologic and clinical overlap across RYR1-RM. Both dominant and recessive modes of inheritance have been documented, with the latter typically associated with a more severe clinical phenotype. As with all congenital myopathies, no FDA-approved treatments exist to date. Here, we review histopathologic, clinical, imaging, and genetic diagnostic features of the main RYR1-RM subtypes. We also discuss the current state of treatments and focus on disease-modulating (nongenetic) therapeutic strategies under development for RYR1-RM. Finally, perspectives for future approaches to treatment development are broached.

The excessive use of antioxidant therapy: A possible cause of male infertility?

Reactive oxygen species and oxidative stress are closely associated with various pathologies such as neurodegenerative diseases, ageing and male infertility. Hence, antioxidants such as vitamin C, vitamin E, N-acetyl cysteine, L-carnitine and folic acid are regularly used in various treatment regimens to protect cells from the damage induced by free radicals. However, given their over-the-counter availability at unnaturally high concentrations and also the fact that they are commonly added to various food products, patients may run a risk of consuming excessive dosages of these compounds, which may then be toxic. The few studies that have assessed antioxidant overuse and the associated adverse effects found that large doses of dietary antioxidant supplements have varying-if any-therapeutic effects even though free radicals clearly damage cells-a phenomenon that has been termed the "antioxidant paradox." Furthermore, overuse of antioxidants such as vitamin C, vitamin E, N-acetyl cysteine may lead to reductive stress, which is reported to be as dangerous to cells as oxidative stress and can be the cause of diseases such as cancer or cardiomyopathy. Therefore, we feel that there is a need for more elaborate research to establish the clear benefits and risks involved in antioxidant therapy for male infertility.

Metabolic enhancers supporting 1-carbon cycle affect sperm functionality: an in vitro comparative study

The sperm plasma membrane is a sensitive target to oxidative stress. The most representative reactive oxygen species (ROS) scavengers in the genital tract, hypotaurine and glutathione, require, for their synthesis, cysteine whose availability is associated with the 1-carbon cycle (1-CC). Human, bovine and ascidian spermatozoa were incubated with compounds supporting the 1-CC (Vitamin B6, Methylcobalamin, 5 Methyl Tetrahydrofolate, Zinc Bisglycinate and N-acetyl-cysteine) (TRT) and compared to the effects induced solely by N-acetyl-cysteine (NAC). In control groups (CNTRL), spermatozoa were incubated with medium alone. After 90 and 180 minutes of incubation, the mitochondrial membrane potential (ΔΨM) in TRT and NAC was significantly (P < 0.01) higher than in CNTRL. At H₂DCFDA evaluation, ROS production differed between species whereas, at 2-OH Ethidium, it significantly decreased in bovine TRT group. Intracellular pH (pH_i) did not significantly vary in relation to treatment. In ascidian spermatozoa, the NAC supplementation decreased external pH, which in turn brought to a pH_i lowering. Buffering seawater with NaHCO₃ reversed the beneficial effects of N-acetyl-cysteine supplementation. In conclusion, both fully supporting the 1-CC and treatment with N-acetyl-cysteine alone improved kinetics, ΔΨM and ROS production in mammalian sperm demonstrating for the first time the direct in vitro effects of these compounds on sperm functionality.

Mancozeb induces testicular dysfunction through oxidative stress and apoptosis: Protective role of N-acetylcysteine antioxidant

Mancozeb (MZB) is one of the fungicides used in pest control programs that might affect human health including reproductive system. The aim of this study was to demonstrate the mechanisms through which MZB induces testicular tissue damage and the probable protective effect of N-acetylcysteine (NAC), a modified amino acid, with antioxidant property, against MZB toxicity in an animal model. Male albino mice ( n = 8) were exposed to different doses of MZB (250 and 500 mg/kg/day) by oral gavage without or with NAC (200 mg/kg, twice/week) for 40 days. Sub-chronic MZB dose-dependently decreased sperm motility and count. Exposure to MZB increased lipid peroxidation and protein carbonyl, while it reduced antioxidant enzymes activities, total antioxidant capacity, and glutathione content. The histopathological examination clearly showed deleterious changes in the testicular structure. At the molecular levels, the results of quantitative real time-poly chain reaction (qRT-PCR) showed that MZB upregulated oxidative stress markers inducible nitric oxide synthase (iNOS) and NADPH oxidase 4 (NOX4) and downregulated expression of the glutathione peroxidase 1 (Gpx1) gene as one of the most important antioxidant enzymes. MZB also induced apoptosis dose-dependently in the testes as determined by the terminal dUTP nick-end labeling assay and immunoblotting. NAC administration decreased the mRNA levels of both iNOS and NOX4 with a concomitant increase in Gpx1 expression. It also significantly decreased MZB-induced oxidative stress and apoptosis. Collectively, the present study showed MZB-induced oxidative damage in testes leading to apoptosis. It revealed that antioxidants such as NAC can mitigate oxidant injury induced by the dithiocarbamate pesticides in the reproductive system.

Histopathological Effects of Titanium Dioxide Nanoparticles and The Possible Protective Role of N-Acetylcysteine on The Testes of Male Albino Rats

BACKGROUND

Titanium dioxide (TiO₂) is a white pigment which is used in paints, plastics, etc. It is reported that TiO₂ induces oxidative stress and DNA damage. N-acetylcysteine (NAC) has been used to fight oxidative stress-induced damage in different tissues. The objective of this study was to evaluate the toxic effects of orally administered TiO₂ nanoparticles and the possible protective effect of NAC on the testes of adult male albino rats.

MATERIALS AND METHODS

In this experimental study, 50 adult male albino rats were classified into five groups. Group I was the negative control, group II was treated with gum acacia solution , group III was treated with NAC, group IV was treated with TiO₂ nanoparticles, and group V was treated with 100 mg/kg of NAC and 1200 mg/kg TiO₂ nanoparticles. Total testosterone, glutathione (GSH), and serum malondialdehyde (MDA) levels were estimated. The testes were subjected to histopathological, electron microscopic examinations, and immunohistochemical detection for tumor necrosis factor (TNF)-α. Cells from the left testis were examined to detect the degree of DNA impairment by using the comet assay.

RESULTS

TiO₂ nanoparticles induced histopathological and ultrastructure changes in the testes as well as positive TNF-α immunoreaction in the testicular tissue. Moreover, there was an increase in serum MDA while a decrease in testosterone and GSH levels in TiO₂ nanoparticles-treated group. TiO₂ resulted in DNA damage. Administration of NAC to TiO₂- treated rats led to improvement of the previous parameters with modest protective effects against DNA damage.

CONCLUSION

TiO₂-induced damage to the testes was mediated by oxidative stress. Notably, administration of NAC protected against TiO₂'s damaging effects.

L-Cysteine Partially Protects Against Acrylamide-Induced Testicular Toxicity

BACKGROUND

Acrylamide is a widespread substance having many areas of utilization. Besides, it also forms a part of high-temperature processed starchy foods. To date, numerous in vivo and in vitro studies have documented that acrylamide has toxic effects on various organ systems.

AIMS

To determine the potential protective effect of L-cysteine on acrylamide-induced testicular toxicity.

STUDY DESIGN

Animal experimentation.

METHODS

We randomly divided 28 rats into four groups as control (0.9% saline), L-cysteine (150 mg/kg), acrylamide (40 mg/kg) and acrylamide + L-cysteine. After a 10-day intraperitoneal injection period, we euthanized the animals, recorded their body and testis weights, collected blood samples for serum testosterone measurement, and excised testes for histopathological and morphometric evaluation. Besides, immunohistochemical scoring of proliferating cell nuclear antigen and bax proteins was performed.

RESULTS

Acrylamide reduced body (p<0.01) and testis weights (p<0.05), seminiferous tubule diameter (p<0.001) and proliferating cell nuclear antigen expression (p<0.05), while it increased bax protein expression (p<0.01) and the percentage of seminiferous tubules that contain multinucleated giant cells (p<0.001), but did not significantly change serum testosterone levels when compared to control. L-cysteine administered with acrylamide decreased multinucleated giant cell number (p<0.001) and reversed the reduced proliferating cell nuclear antigen positivity (p<0.001), but did not restore other parameters compared with the acrylamide alone-treated group.

CONCLUSION

Taking into account the dose and duration employed, the present study concluded that L-cysteine partially protects testis against acrylamide-induced toxic effects.

Systematic review of antioxidant types and doses in male infertility: Benefits on semen parameters, advanced sperm function, assisted reproduction and live-birth rate

Objective

To explore the current evidence concerning the effect of oral antioxidant supplementation on various male fertility outcomes, as antioxidants are widely available compounds that are commonly used for the treatment of male infertility.

Materials and methods

PubMed, Medline and Cochrane electronic databases were searched according to a modified Preferred Reporting Items for Systemic Reviews and Meta-Analyses (PRISMA) guidelines looking for studies investigating the effect of antioxidant therapy on infertile men. The studies were explored looking for antioxidants: (i) types and doses; (ii) mechanism of action and rationale for use; and (iii) effect on the different outcome measures reported.

Results

In all, 26 studies reported a significant positive effect of antioxidant therapy on basic semen parameters, advanced sperm function, outcomes of assisted reproductive therapy, and live-birth rate. Vitamin E, vitamin C, carnitines, N-acetyl cysteine, co-enzyme Q10, zinc, selenium, folic acid and lycopene were most commonly used. The vitamins’ mechanism of action and reported doses is presented in Table 1, Table 2.

Conclusion

Antioxidants generally have a favourable effect on male fertility. Further studies are needed to identify the optimal antioxidant regimen that can be used safely and efficiently in clinical practice.

Role of Antioxidants in Assisted Reproductive Techniques

Oxidative stress (OS) has been recognized as a significant cause of suboptimal assisted reproductive outcome. Many of the sperm preparation and manipulation procedures that are necessary in the in vitro environment can result in excessive production of reactive oxygen species (ROS) thereby exposing the gametes and growing embryos to significant oxidative damage. Antioxidants have long been utilized in the management of male subfertility as they can counterbalance the elevated levels of ROS inducing a high state of OS. Few studies have looked into the clinical effectiveness of antioxidants in patients undergoing assisted reproduction. While an overall favorable outcome has been perceived, the specific clinical indication and optimal antioxidant regimen remain unknown. The goal of our review is to explore the sources of ROS in the in vitro environment and provide a clinical scenario-based approach to identify the circumstances where antioxidant supplementation is most beneficial to enhance the outcome of assisted reproduction.

Conservative Nonhormonal Options for the Treatment of Male Infertility: Antibiotics, Anti-Inflammatory Drugs, and Antioxidants

The nonhormonal medical treatment can be divided into empirical, when the cause has not been identified, and nonempirical, if the pathogenic mechanism causing male infertility can be solved or ameliorated. The empirical nonhormonal medical treatment has been proposed for patients with idiopathic or noncurable oligoasthenoteratozoospermia and for normozoospermic infertile patients. Anti-inflammatory, fibrinolytic, and antioxidant compounds, oligo elements, and vitamin supplementation may be prescribed. Infection, inflammation, and/or increased oxidative stress often require a specific treatment with antibiotics, anti-inflammatory drugs, and/or antioxidants. Combined therapies can contribute to improve sperm quality.

Antioxidant therapy in idiopathic oligoasthenoteratozoospermia

Introduction:

Idiopathic oligoasthenoteratozoospermia (iOAT) is commonly encountered during the evaluation of men with infertility. Antioxidants have been utilized empirically in the treatment of iOAT based on their ability to reverse oxidative stress (OS)-induced sperm dysfunction often encountered in this patient population.

Methods:

A literature search was performed using MEDLINE/PubMed, focusing on publications of antioxidant therapies for iOAT. The main objective of our review article was to report the rationale and available evidence supporting the use of antioxidants.

Results:

Antioxidants such as glutathione, vitamins E and C, carnitines, coenzyme-Q10, N-acetylcysteine, selenium, zinc, folic acid, and lycopene have been shown to reduce OS-induced sperm damage. While rigorous scientific evidence in the form of double-blind, placebo-controlled clinical trials is limited, recent systematic reviews and meta-analyses have reported a beneficial effect of antioxidants on semen parameters and live birth rates.

Conclusion:

Additional randomized controlled studies are required to confirm the efficacy and safety of antioxidant supplementation in the medical treatment of idiopathic male infertility as well as the dosage required to improve semen parameters, fertilization rates, and pregnancy outcomes in iOAT.

A Preliminary Study: N-acetyl-L-cysteine Improves Semen Quality following Varicocelectomy

Background

Surgery is considered the primary treatment for male infertility from clinical varicocele. One of the main events associated with varicocele is excessive production of reactive oxygen species (ROS). N-acetyl-L-cysteine (NAC), an antioxidant that scavenges free radicals, is considered a supplement to alleviate glutathione (GSH) depletion during oxidative stress. Despite beneficial effects of NAC in other pathological events, there is no report on the effect of NAC in individuals with varicocele. Therefore, the aim of this study is to evaluate the outcome of NAC on semen quality, protamine content, DNA damage, oxidative stress and fertility following varicocelectomy.

Materials and Methods

This prospective clinical trial included 35 infertile men with varicocele randomly divided into control (n=20) and NAC (n=15) groups. We assessed semen parameters, protamine content [chromomycin A3 (CMA3)], DNA integrity [terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL)] and oxidative stress [2', 7'-dichlorodihydrofluorescein-diacetate (DCFH-DA)] before and three months after varicocelectomy.

Results

Percentage of abnormal semen parameters, protamine deficiency, DNA fragmentation and oxidative stress were significantly decreased in both groups compared to before surgery. We calculated the percentage of improvement in these parameters compared to before surgery for each group, then compared the results between the groups. Only percentage of protamine deficiency and DNA fragmentation significantly differed between the NAC and control groups.

Conclusion

The results of this study, for the first time, revealed that NAC improved chromatin integrity and pregnancy rate when administered as adjunct therapy post-varico- celectomy (Registeration Number: IRCT201508177223N5).

Antioxidants for male subfertility

BACKGROUND

Between 30% to 80% of male subfertility cases are considered to be due to the damaging effects of oxidative stress on sperm and 1 man in 20 will be affected by subfertility. Antioxidants are widely available and inexpensive when compared to other fertility treatments and many men are already using these to improve their fertility. It is thought that oral supplementation with antioxidants may improve sperm quality by reducing oxidative stress. Pentoxifylline, a drug that acts like an antioxidant, was also included in this review.  

OBJECTIVES

This Cochrane review aimed to evaluate the effectiveness and safety of oral supplementation with antioxidants for subfertile male partners in couples seeking fertility assistance.

SEARCH METHODS

We searched the Cochrane Menstrual Disorders and Subfertility Group Specialised Register, CENTRAL, MEDLINE, EMBASE, CINAHL, PsycINFO and AMED databases (from inception until January 2014); trial registers; sources of unpublished literature and reference lists. An updated search was run in August 2014 when potentially eligible studies were placed in 'Studies awaiting assessment'.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing any type or dose of antioxidant supplement (single or combined) taken by the subfertile male partner of a couple seeking fertility assistance with a placebo, no treatment or another antioxidant.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected eligible studies, extracted the data and assessed the risk of bias of the included studies. The primary review outcome was live birth; secondary outcomes included clinical pregnancy rates, adverse events, sperm DNA fragmentation, sperm motility and concentration. Data were combined, where appropriate, to calculate pooled odds ratios (ORs) or mean differences (MD) and 95% confidence intervals (CIs). Statistical heterogeneity was assessed using the I(2) statistic. We assessed the overall quality of the evidence for the main outcomes using GRADE methods.  

MAIN RESULTS

This updated review included 48 RCTs that compared single and combined antioxidants with placebo, no treatment or another antioxidant in a population of 4179 subfertile men. The duration of the trials ranged from 3 to 26 weeks with follow up ranging from 3 weeks to 2 years. The men were aged from 20 to 52 years. Most of the men enrolled in these trials had low total sperm motility and sperm concentration. One study enrolled men after varicocelectomy, one enrolled men with a varicocoele, and one recruited men with chronic prostatitis. Three trials enrolled men who, as a couple, were undergoing in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) and one trial enrolled men who were part of a couple undergoing intrauterine insemination (IUI). Funding sources were stated by 15 trials. Four of these trials stated that funding was from a commercial source and the remaining 11 obtained funding through non-commercial avenues or university grants. Thirty-three trials did not report any funding sources.A limitation of this review was that in a sense we had included two different groups of trials, those that reported on the use of antioxidants and the effect on live birth and clinical pregnancy, and a second group that reported on sperm parameters as their primary outcome and had no intention of reporting the primary outcomes of this review. We included 25 trials reporting on sperm parameters and only three of these reported on live birth or clinical pregnancy. Other limitations included poor reporting of study methods, imprecision, the small number of trials providing usable data, the small sample size of many of the included studies and the lack of adverse events reporting. The evidence was graded as 'very low' to 'low'. The data were current to 31 January 2014.Live birth: antioxidants may have increased live birth rates (OR 4.21, 95% CI 2.08 to 8.51, P< 0.0001, 4 RCTs, 277 men, I(2) = 0%, low quality evidence). This suggests that if the chance of a live birth following placebo or no treatment is assumed to be 5%, the chance following the use of antioxidants is estimated to be between 10% and 31%. However, this result was based on only 44 live births from a total of 277 couples in four small studies.Clinical pregnancy rate: antioxidants may have increased clinical pregnancy rates (OR 3.43, 95% CI 1.92 to 6.11, P < 0.0001, 7 RCTs, 522 men, I(2) = 0%, low quality evidence). This suggests that if the chance of clinical pregnancy following placebo or no treatment is assumed to be 6%, the chance following the use of antioxidants is estimated at between 11% and 28%. However, there were only seven small studies in this analysis and the quality of the evidence was rated as low.Miscarriage: only three trials reported on this outcome and the event rate was very low. There was insufficient evidence to show whether there was a difference in miscarriage rates between the antioxidant and placebo or no treatment groups (OR 1.74, 95% CI 0.40 to 7.60, P = 0.46, 3 RCTs, 247 men, I(2) = 0%, very low quality evidence). The findings suggest that in a population of subfertile men with an expected miscarriage rate of 2%, use of an antioxidant would result in the risk of a miscarriage lying between 1% and 13%.Gastrointestinal upsets: there was insufficient evidence to show whether there was a difference in gastrointestinal upsets when antioxidants were compared to placebo or no treatment as the event rate was very low (OR 1.60, 95% CI 0.47 to 5.50, P = 0.46, 6 RCTs, 429 men, I(2) = 0%).We were unable to draw any conclusions from the antioxidant versus antioxidant comparison as not enough trials compared the same interventions.

AUTHORS' CONCLUSIONS

There is low quality evidence from only four small randomised controlled trials suggesting that antioxidant supplementation in subfertile males may improve live birth rates for couples attending fertility clinics. Low quality evidence suggests that clinical pregnancy rates may increase. There is no evidence of increased risk of miscarriage but this is uncertain as the evidence is of very low quality. Data were lacking on other adverse effects. Further large well-designed randomised placebo-controlled trials are needed to clarify these results.

Rats with metabolic syndrome resist the protective effects of N-acetyl l-cystein against impaired spermatogenesis induced by high-phosphorus/zinc-free diet

Consumption of relatively high amounts of processed food can result in abnormal nutritional status, such as zinc deficiency or phosphorus excess. Moreover, hyperphosphatemia and hypozincemia are found in some patients with diabetic nephropathy and metabolic syndrome. The present study investigated the effects of high-phosphorus/zinc-free diet on the reproductive function of spontaneously hypertensive rats/NDmcr-cp (SHR/cp), a model of the metabolic syndrome. We also investigated the effects of antioxidant, N-acetyl-l-cysteine (NAC), on testicular dysfunction under such conditions. Male SHR/cp and control rats (Wistar Kyoto rats, WKY) were divided into three groups; rats fed control diet (P 0.3%, w/w; Zn 0.2%, w/w), high-phosphorus and zinc-deficient diet (P 1.2%, w/w; Zn 0.0%, w/w) with vehicle, or high-phosphorus and zinc-deficient diet with NAC (1.5mg/g/day) for 12 weeks (n=6 or 8 rats/group). The weights of testis and epididymis were significantly reduced by high-phosphate/zinc-free diet in both SHR/cp and WKY. The same diet significantly reduced caudal epididymal sperm count and motility and induced histopathological changes in the testis in both strains. Treatment with NAC provided significant protection against the toxic effects of the diet on testicular function in WKY, but not in SHR/cp. The lack of the protective effects of NAC on impaired spermatogenesis in SHR/cp could be due to the more pronounced state of oxidative stress observed in these rats compared with WKY.

Effects of N-acetyl-L-cysteine on bleomycin induced oxidative stress in malignant testicular germ cell tumors

Testicular cancer is a very common cancer in males aged 15-44 years. Bleomycin is used in chemotherapy regimens in the treatment of patients having testicular germ-cell tumor. Bleomycin generates oxygen radicals, induces oxidative cleavage of DNA strand and induces apoptosis in cancer cells. There is no study in the literature investigating effects of N-Acetyl-L-Cysteine (NAC) on bleomycin-induced oxidative stress in testicular germ cell tumors. For this reason, we studied effects of NAC on oxidative stress produced in wild-type NTera-2 and p53-mutant NCCIT testis cancer cells incubated with bleomycin and compared the results with H(2)O(2) which directly produces oxidative stress. We determined protein carbonyl content, thiobarbituric acid reactive substances (TBARS), glutathione (GSH), 8-isoprostane, lipid hydroperoxide levels and total antioxidant capacity in both testicular cancer cells. Bleomycin and H(2)O(2) significantly increased 8-isoprostane, TBARS, protein carbonyl and lipid hydroperoxide levels in NTera-2 and NCCIT cells. Bleomycin and H(2)O(2) significantly decreased antioxidant capacity and GSH levels in both cell lines. Co-incubation with NAC significantly decreased lipid hydroperoxide, 8-isoprostane, protein carbonyl content and TBARS levels increased by bleomycin and H(2)O(2). NAC enhanced GSH levels and antioxidant capacity in the NTera-2 and NCCIT cells. It can be concluded that NAC diminishes oxidative stress in human testicular cancer cells induced by bleomycin and H(2)O(2).

Differential modulation of apoptotic gene expression by N-acetyl-L-cysteine in Leydig cells stimulated persistently with hCG in vivo

The present study was designed to investigate the molecular mechanisms of NAC (150 mg/kg bw twice/week) action in vivo under repeated hCG (100 IU/rat/day) stimulation to adult rats. Leydig cell refractoriness led to a significant decline in serum testosterone and intracellular cAMP by day 30 of chronic hCG intervention which improved significantly following NAC co-administration. It inhibited the rise in lipid peroxidation, improved the activity of antioxidant enzymes along with intracellular glutathione and total antioxidant capacity in the target cells. Leydig cell apoptosis declined significantly (P<0.001) with down-regulation of upstream, Fas, FasL, caspase-8, Bax and caspase-9, JNK/pJNK and downstream caspase-3 and PARP. On the other hand, anti-apoptotic Bcl2, NF-kβ, and Akt were up-regulated. Taken together, the above findings indicate that the specificity of NAC action was not restricted to regulating marker proteins in the extrinsic and JNK pathways as seen in vitro but extended to include intrinsic pathway of metazoan apoptosis as well.

Cysteine addition on short-term cooled boar semen preservation and its relationship with swine field fertility

Artificial insemination is routinely used in the swine industry to reduce the costs of production through to increase the efficiency of the refrigerated boar semen process. The objective of this study was to evaluate the effect of different levels of cysteine (CYS) added to the Beltsville Thawing Solution (BTS) extender semen during cooling for up to 72 hours. Ejaculated from three boars were collected with the gloved-hand technique and semen aliquots were diluted in BTS as follow: BTS only (BTS), BTS + 0.1mM cysteine (CYS0.1), BTS + 0.5mM cysteine (CYS0.5), BTS + 1.0mM cysteine (CYS1.0), BTS + 2.5mM cysteine (CYS2.5), BTS + 5.0mM cysteine (CYS5.0), BTS + 10.0mM cysteine (CYS10.0), and BTS + 20.0mM cysteine (CYS20.0). Evaluation of sperm integrity were analyzed using 0.5mg/ml propidium iodide (plasma membrane), 100µg/ml isothiocynate-conjugated Pisum sativun agglutinin (acrosomal membrane) and 153µM 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl carbocyanine iodide (mitochondria potential) after semen dilution at specific times (0, 24, 48 and 72 hours). Additionally, we also evaluated the effects of 5.0 mM CYS addition in the BTS extender on the maintenance of sperm quality and their influence on fertility in the swine production. After artificial insemination, animals were evaluated based on the estrous return and the number of piglet's born. Cysteine at concentrations of 10.0 and 20.0mM resulted in more pronounced reductions even at the time zero. Semen viability decreased to levels below 10% at these high levels of CYS in the first 24 hour of storage at 17ºC. At the end of the storage time, less than 65% of sperm cells had intact plasma membrane in all groups. The sperm viability decreased significantly when the semen was added at high concentrations of CYS (time "0"; CYS10.0 and CYS20.0; p<0.05), when compared to the other CYS concentrations. The BTS (10.20±0.39) treated group showed a lower rate of estrus return when compared to other (BTSCYS; 86.05±039), and it showed also the highest total number of piglets borne per treatment (12.71±3.38 vs. 9.00±3.38, respectively). In conclusion, the addition of CYS in the BTS semen extender did not maintain spermatic viability of boar cooled spermatozoa and it results in a higher percentage of return to estrus and lower number of piglets borne.

The role of antioxidant therapy in the treatment of male infertility: an overview

In recent years, many studies have focused on the effect of oxidative stress, reactive oxygen species (ROS) and antioxidants on the male eproductive system. Under physiological conditions, sperm produces small amounts of ROS, which are needed for fertilisation, acrosome reaction and capacitation. However, if an increased production of ROS is not associated with a similar increase in scavenging systems, peroxidative damage of the sperm plasma membrane and loss of DNA integrity typically occur, which leads to cell death and reduced fertility. Furthermore, since there is no linear correlation between sperm quality and pregnancy rates, an improvement in semen parameters should not be the sole outcome considered in studies of antioxidant therapies. A definitive conclusion regarding the benefit of these therapies is difficult to obtain, as most of the previous studies lacked control groups, considered different antioxidants in different combinations and doses, or did not evaluate pregnancy rates in previously infertile couples. Even if beneficial effects were reported in a few cases of male infertility, more multicentre, double-blind studies performed with the same criteria are necessary for an increased understanding of the effects of various antioxidants on fertility.

Antioxidant therapy in male infertility: fact or fiction?

Infertile men have higher levels of semen reactive oxygen species (ROS) than do fertile men. High levels of semen ROS can cause sperm dysfunction, sperm DNA damage and reduced male reproductive potential. This observation has led clinicians to treat infertile men with antioxidant supplements. The purpose of this article is to discuss the rationale for antioxidant therapy in infertile men and to evaluate the data on the efficacy of dietary and in vitro antioxidant preparations on sperm function and DNA damage. To date, most clinical studies suggest that dietary antioxidant supplements are beneficial in terms of improving sperm function and DNA integrity. However, the exact mechanism of action of dietary antioxidants and the optimal dietary supplement have not been established. Moreover, most of the clinical studies are small and few have evaluated pregnancy rates. A beneficial effect of in vitro antioxidant supplements in protecting spermatozoa from exogenous oxidants has been demonstrated in most studies; however, the effect of these antioxidants in protecting sperm from endogenous ROS, gentle sperm processing and cryopreservation has not been established conclusively.

Antioxidants for male subfertility

BACKGROUND

Between 30% to 80% of male subfertility cases are considered to be due to the damaging effects of oxidative stress on sperm. Oral supplementation with antioxidants may improve sperm quality by reducing oxidative stress.  

OBJECTIVES

This Cochrane review aimed to evaluate the effect of oral supplementation with antioxidants for male partners of couples undergoing assisted reproduction techniques (ART).

SEARCH STRATEGY

We searched the Cochrane Menstrual Disorders and Subfertility Group Register, CENTRAL (The Cochrane Library), MEDLINE, EMBASE, CINAHL, PsycINFO and AMED databases (from their inception until Febuary 2010), trial registers, sources of unpublished literature, reference lists and we asked experts in the field.

SELECTION CRITERIA

We included randomised controlled trials comparing any type or dose of antioxidant supplement (single or combined) taken by the male partner of a couple seeking fertility assistance with placebo, no treatment or another antioxidant. The outcomes were live birth, pregnancy, miscarriage, stillbirth, sperm DNA damage, sperm motility, sperm concentration and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion and trial quality, and extracted data.  

MAIN RESULTS

We included 34 trials with 2876 couples in total. Live birth: three trials reported live birth. Men taking oral antioxidants had an associated statistically significant increase in live birth rate (pooled odds ratio (OR) 4.85, 95% CI 1.92 to 12.24; P = 0.0008, I(2) = 0%) when compared with the men taking the control. This result was based on 20 live births from a total of 214 couples in only three studies.Pregnancy rate: there were 96 pregnancies in 15 trials including 964 couples. Antioxidant use was associated with a statistically significant increased pregnancy rate compared to control (pooled OR 4.18, 95% CI 2.65 to 6.59; P < 0.00001, I(2) = 0%).Side effects: no studies reported evidence of harmful side effects of the antioxidant therapy used.

AUTHORS' CONCLUSIONS

The evidence suggests that antioxidant supplementation in subfertile males may improve the outcomes of live birth and pregnancy rate for subfertile couples undergoing ART cycles. Further head to head comparisons are necessary to identify the superiority of one antioxidant over another.