Melatonin therapy adds extra benefit to varicecelectomy in terms of sperm parameters, hormonal profile and total antioxidant capacity: A placebo-controlled, double-blind trial

Effects of Varicocele Repair on Sperm DNA Fragmentation and Seminal Malondialdehyde Levels in Infertile Men with Clinical Varicocele: A Systematic Review and Meta-Analysis

PURPOSE

Varicoceles can be a source of elevated seminal oxidative stress (OS) and sperm DNA fragmentation (SDF). However, it remains unclear whether varicocele repair (VR) could reduce these parameters. This systematic review and meta-analysis (SRMA) aims to investigate the impact of VR on SDF and seminal malondialdehyde (MDA).

MATERIALS AND METHODS

A literature search was performed in Scopus, PubMed, Ovid, Embase, and Cochrane databases. This SRMA included randomized controlled trials and observational studies reporting the pre- and postoperative levels of SDF and seminal OS in infertile men with clinical varicocele that underwent VR. Subgroup analyses included techniques of VR and SDF testing. The effect size was expressed as standardized mean difference (SMD).

RESULTS

Out of 1,632 abstracts assessed for eligibility, 29 studies with 1,491 infertile men were included. The analysis showed a significant reduction in SDF after VR, compared to preoperative values (SMD -1.125, 95% confidence interval [CI] -1.410, -0.840; p<0.0001) with high inter-study heterogeneity (I²=90.965%). Reduction in SDF was evident with microsurgical technique and non-microsurgical inguinal approaches (SMD -1.014, 95% CI -1.263, -0.765; p<0.0001, and SMD -1.495, 95% CI -2.116, -0.873; p<0.0001), respectively. Reduction in SDF was significant irrespective of testing was done by sperm chromatin dispersion (SMD -2.197, 95% CI -3.187, -1.207; p<0.0001), sperm chromatin structure assay (SMD -0.857, 95% CI -1.156, -0.559; p<0.0001) or TUNEL (SMD -1.599, 95% CI -2.478, -0.719; p<0.0001). A significant decrease in seminal MDA levels was observed following VR (SMD -2.450, 95% CI -3.903 to -0.997, p=0.001) with high inter-study heterogeneity (I²=93.7%).

CONCLUSIONS

Using pre- and post-intervention data, this SRMA indicates a significant reduction in SDF and seminal MDA levels in infertile men with clinical varicocele treated with VR. These findings may have important implications for the future management of this selected group of infertile patients.

Does Varicocele Repair Improve Conventional Semen Parameters? A Meta-Analytic Study of Before-After Data

PURPOSE

The purpose of this meta-analysis is to study the impact of varicocele repair in the largest cohort of infertile males with clinical varicocele by including all available studies, with no language restrictions, comparing intra-person conventional semen parameters before and after the repair of varicoceles.

MATERIALS AND METHODS

The meta-analysis was performed according to PRISMA-P and MOOSE guidelines. A systematic search was performed in Scopus, PubMed, Cochrane, and Embase databases. Eligible studies were selected according to the PICOS model (Population: infertile male patients with clinical varicocele; Intervention: varicocele repair; Comparison: intra-person before-after varicocele repair; Outcome: conventional semen parameters; Study type: randomized controlled trials [RCTs], observational and case-control studies).

RESULTS

Out of 1,632 screened abstracts, 351 articles (23 RCTs, 292 observational, and 36 case-control studies) were included in the quantitative analysis. The before-and-after analysis showed significant improvements in all semen parameters after varicocele repair (except sperm vitality); semen volume: standardized mean difference (SMD) 0.203, 95% CI: 0.129-0.278; p<0.001; I²=83.62%, Egger's p=0.3329; sperm concentration: SMD 1.590, 95% CI: 1.474-1.706; p<0.001; I²=97.86%, Egger's p<0.0001; total sperm count: SMD 1.824, 95% CI: 1.526-2.121; p<0.001; I²=97.88%, Egger's p=0.0063; total motile sperm count: SMD 1.643, 95% CI: 1.318-1.968; p<0.001; I²=98.65%, Egger's p=0.0003; progressive sperm motility: SMD 1.845, 95% CI: 1.537%-2.153%; p<0.001; I²=98.97%, Egger's p<0.0001; total sperm motility: SMD 1.613, 95% CI 1.467%-1.759%; p<0.001; l2=97.98%, Egger's p<0.001; sperm morphology: SMD 1.066, 95% CI 0.992%-1.211%; p<0.001; I²=97.87%, Egger's p=0.1864.

CONCLUSIONS

The current meta-analysis is the largest to date using paired analysis on varicocele patients. In the current meta-analysis, almost all conventional semen parameters improved significantly following varicocele repair in infertile patients with clinical varicocele.

Protective effects of melatonin against physical injuries to testicular tissue: A systematic review and meta-analysis of animal models

BACKGROUND

Modern societies face infertility as a global challenge. There are certain environmental conditions and disorders that damage testicular tissue and may cause male infertility. Melatonin, as a potential antioxidant, may protect testicular tissue. Therefore, we conducted this systematic review and meta-analysis to evaluate the effects of melatonin in animal models against physical, heat, and ischemic damage to the testicular tissue.

METHODS

PubMed, Scopus, and Web of Science were systematically searched to identify animal trials evaluating the protective effect of melatonin therapy on rodent testicular tissue when it is exposed to physical, thermal, ischemic, or hypobaric oxygen stress. Random-effect modeling was used to estimate the standardized mean difference and 95% confidence intervals based on the pooled data. Additionally, the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) tool was used to assess the risk of bias. The study protocol was prospectively registered in PROSPERO (CRD42022354599).

RESULTS

A total of 41 studies were eligible for review out of 10039 records. Studies employed direct heat, cryptorchidism, varicocele, torsion-detorsion, testicular vascular occlusion, hypobaric hypoxia, ischemia-reperfusion, stress by excessive or restraint activity, spinal cord injury, and trauma to induce stress in the subjects. The histopathological characteristics of testicular tissue were generally improved in rodents by melatonin therapy. Based on the pooled data, sperm count, morphology, forward motility, viability, Johnsen's biopsy score, testicular tissue glutathione peroxidase, and superoxide dismutase levels were higher in the melatonin treatment rodent arms. In contrast, the malondialdehyde level in testicular tissue was lower in the treatment rodent arms. The included studies suffered from a high risk of bias in most of the SYRCLE domains.

CONCLUSION

This study concludes that melatonin therapy was associated with improved testicular histopathological characteristics, reproductive hormonal panel, and tissue markers of oxidative stress in male rodents with physical, ischemic, and thermal testicular injuries. In this regard, melatonin deserves scientific investigations as a potential protective drug against rodent male infertility.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022354599.

Impact of Antioxidant Therapy on Natural Pregnancy Outcomes and Semen Parameters in Infertile Men: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

PURPOSE

Seminal oxidative stress (OS) is a recognized factor potentially associated with male infertility, but the efficacy of antioxidant (AOX) therapy is controversial and there is no consensus on its utility. Primary outcomes of this study were to investigate the effect of AOX on spontaneous clinical pregnancy, live birth and miscarriage rates in male infertile patients. Secondary outcomes were conventional semen parameters, sperm DNA fragmentation (SDF) and seminal OS.

MATERIALS AND METHODS

Literature search was performed using Scopus, PubMed, Ovid, Embase, and Cochrane databases. Only randomized controlled trials (RCTs) were included and the meta-analysis was conducted according to PRISMA guidelines.

RESULTS

We assessed for eligibility 1,307 abstracts, and 45 RCTs were finally included, for a total of 4,332 infertile patients. We found a significantly higher pregnancy rate in patients treated with AOX compared to placebo-treated or untreated controls, without significant inter-study heterogeneity. No effects on live-birth or miscarriage rates were observed in four studies. A significantly higher sperm concentration, sperm progressive motility, sperm total motility, and normal sperm morphology was found in patients compared to controls. We found no effect on SDF in analysis of three eligible studies. Seminal levels of total antioxidant capacity were significantly higher, while seminal malondialdehyde acid was significantly lower in patients than controls. These results did not change after exclusion of studies performed following varicocele repair.

CONCLUSIONS

The present analysis upgrades the level of evidence favoring a recommendation for using AOX in male infertility to improve the spontaneous pregnancy rate and the conventional sperm parameters. The failure to demonstrate an increase in live-birth rate, despite an increase in pregnancy rates, is due to the very few RCTs specifically assessing the impact of AOX on live-birth rate. Therefore, further RCTs assessing the impact of AOX on live-birth rate and miscarriage rate, and SDF will be helpful.

Coping with Oxidative Stress in Reproductive Pathophysiology and Assisted Reproduction: Melatonin as an Emerging Therapeutical Tool

Infertility is an increasing global public health concern with socio-psychological implications for affected couples. Remarkable advances in reproductive medicine have led to successful treatments such as assisted reproductive techniques (ART). However, the search for new therapeutic tools to improve ART success rates has become a research hotspot. In the last few years, pineal indolamine melatonin has been investigated for its powerful antioxidant properties and its role in reproductive physiology. It is considered a promising therapeutical agent to counteract the detrimental effects associated with oxidative stress in fertility treatments. The aim of the present narrative review was to summarize the current state of the art on the importance of melatonin in reproductive physiology and to provide a critical evaluation of the data available encompassing basic, translational and clinical studies on its potential use in ART to improve fertility success rates.

Coenzyme Q10 and Melatonin for the Treatment of Male Infertility: A Narrative Review

BACKGROUND

Lifestyle and environmental factors can negatively impact fertility by means of oxidative stress. In this context, antioxidant supplementation therapy has gained much interest in recent years, and different molecules, alone or in combination, have been studied.

OBJECTIVE

The purpose of the present review is to investigate the evidence regarding the efficacy of coenzyme Q10 (CoQ10) and melatonin on male infertility.

METHODS

A literature search using PUBMED database from 2000 to October 2022 was performed to explore the role of CoQ10 and melatonin on male reproductive function.

CONCLUSIONS

The analysis involved a narrative synthesis. CoQ10, alone or in combination, appears to reduce testicular oxidative stress and sperm DNA fragmentation and to improve sperm parameters; particularly sperm motility. Moreover, CoQ10 treatment is associated with higher pregnancy rates, both naturally and through assisted reproductive technology (ART). Larger studies are needed to precisely determine its clinical efficacy. Melatonin is a known antioxidant and preclinical studies have shown its ability to modulate reproductive function through hormonal and immune system regulation and sperm cell proliferation. Regardless, clinical studies are necessary to assess its potential in male infertility.

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.

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, AMED, and two trial registers were searched on 15 February 2021, together with reference checking and contact with 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 men with idiopathic infertility and normal semen parameters or 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 90 studies with a total population of 10,303 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 medically assisted reproduction (MAR). Investigators compared and combined 20 different oral antioxidants. The evidence was of 'low' to 'very low' certainty: the main limitation was that out of the 67 included studies in the meta-analysis only 20 studies reported clinical pregnancy, and of those 12 reported on live birth. The evidence is current up to February 2021. Live birth: antioxidants may lead to increased live birth rates (odds ratio (OR) 1.43, 95% confidence interval (CI) 1.07 to 1.91, P = 0.02, 12 RCTs, 1283 men, I2 = 44%, very low-certainty evidence). Results in the studies contributing to the analysis of live birth rate suggest that if the baseline chance of live birth following placebo or no treatment is assumed to be 16%, the chance following the use of antioxidants is estimated to be between 17% and 27%. However, this result was based on only 246 live births from 1283 couples in 12 small or medium-sized studies. When studies at high risk of bias were removed from the analysis, there was no evidence of increased live birth (Peto OR 1.22, 95% CI 0.85 to 1.75, 827 men, 8 RCTs, P = 0.27, I2 = 32%). Clinical pregnancy rate: antioxidants may lead to increased clinical pregnancy rates (OR 1.89, 95% CI 1.45 to 2.47, P < 0.00001, 20 RCTs, 1706 men, I2 = 3%, low-certainty evidence) compared with placebo or no treatment. This suggests that, in the studies contributing to the analysis of clinical pregnancy, if the baseline chance of clinical pregnancy following placebo or no treatment is assumed to be 15%, the chance following the use of antioxidants is estimated to be between 20% and 30%. This result was based on 327 clinical pregnancies from 1706 couples in 20 small studies. Adverse events Miscarriage: only six studies reported on this outcome and the event rate was very low. No evidence of a difference in miscarriage rate was found between the antioxidant and placebo or no treatment group (OR 1.46, 95% CI 0.75 to 2.83, P = 0.27, 6 RCTs, 664 men, I2 = 35%, very low-certainty evidence). The findings suggest that in a population of subfertile couples, with male factor infertility, with an expected miscarriage rate of 5%, the risk of miscarriage following the use of an antioxidant would be between 4% and 13%. Gastrointestinal: antioxidants may lead to an increase in mild gastrointestinal discomfort when compared with placebo or no treatment (OR 2.70, 95% CI 1.46 to 4.99, P = 0.002, 16 RCTs, 1355 men, I2 = 40%, low-certainty evidence). This suggests that if the chance of gastrointestinal discomfort following placebo or no treatment is assumed to be 2%, the chance following the use of antioxidants is estimated to be between 2% and 7%. However, this result was based on a low event rate of 46 out of 1355 men in 16 small or medium-sized studies, and the certainty of the evidence was rated low and heterogeneity was high. We were unable to draw conclusions from the antioxidant versus antioxidant comparison as insufficient studies compared the same interventions.

AUTHORS' CONCLUSIONS

In this review, there is very low-certainty evidence from 12 small or medium-sized randomised controlled trials suggesting that antioxidant supplementation in subfertile males may improve live birth rates for couples attending fertility clinics. Low-certainty evidence suggests that clinical pregnancy rates may increase. There is no evidence of increased risk of miscarriage, however antioxidants may give more mild gastrointestinal discomfort, based on very low-certainty evidence. Subfertile 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 studying infertile men and reporting on pregnancy and live births are still required to clarify the exact role of antioxidants.

Age-Related Decline of Male Fertility: Mitochondrial Dysfunction and the Antioxidant Interventions

Mitochondria are structurally and functionally unique organelles in male gametes. Apparently, as the only organelles remaining in mature sperm, mitochondria not only produce adeno-sine triphosphate (ATP) through oxidative phosphorylation (OXPHOS) to support sperm mobility, but also play key roles in regulating reactive oxidation species (ROS) signaling, calcium homeostasis, steroid hormone biosynthesis, and apoptosis. Mitochondrial dysfunction is often associated with the aging process. Age-dependent alterations of the epididymis can cause alterations in sperm mitochondrial functioning. The resultant cellular defects in sperm have been implicated in male infertility. Among these, oxidative stress (OS) due to the overproduction of ROS in mitochondria may represent one of the major causes of these disorders. Excessive ROS can trigger DNA damage, disturb calcium homeostasis, impair OXPHOS, disrupt the integrity of the sperm lipid membrane, and induce apoptosis. Given these facts, scavenging ROS by antioxidants hold great potential in terms of finding promising therapeutic strategies to treat male infertility. Here, we summarize the progress made in understanding mitochondrial dysfunction, aging, and male infertility. The clinical potential of antioxidant interventions was also discussed.

Role of Oxidative Stress in Varicocele

According to the official statistics of the World Health Organization, at least 48 million couples and 186 million people suffer from infertility. Varicocele has been recognized as the leading cause of male infertility and can affect spermatogenesis and cause testicular and epididymal disorders through multiple diverse pathophysiological processes. Reactive oxygen species (ROS) produced by oxidative stress have been reconciled as an important pathogenic factor throughout the course of varicocele. Testis respond to heat stress, hypoxia, and inflammation at the cost of producing excessive ROS. High levels of ROS can lead to infertility not only through lipid peroxidation or DNA damage, but also by inactivating enzymes and proteins in spermatogenesis. This review studies the oxidative stress and its role in the pathophysiology and molecular biology of varicocele in the context of a decline in fertility.

Safety of higher doses of melatonin in adults: A systematic review and meta-analysis

Melatonin is commonly used for sleep and jetlag at low doses. However, there is less documentation on the safety of higher doses, which are being increasingly used for a wide variety of conditions, including more recently COVID-19 prevention and treatment. The aim of this review was to investigate the safety of higher doses of melatonin in adults. Medline, Scopus, Embase and PsycINFO databases from inception until December 2019 with convenience searches until October 2020. Randomised controlled trials investigating high-dose melatonin (≥10 mg) in human adults over 30 years of age were included. Two investigators independently abstracted articles using PRISMA guidelines. Risk of bias was assessed by a committee of three investigators. 79 studies were identified with a total of 3861 participants. Studies included a large range of medical conditions. The meta-analysis was pooled data using a random effects model. The outcomes examined were the number of adverse events (AEs), serious adverse events (SAEs) and withdrawals due to AEs. A total of 29 studies (37%) made no mention of the presence or absence of AEs. Overall, only four studies met the pre-specified low risk of bias criteria for meta-analysis. In that small subset, melatonin did not cause a detectable increase in SAEs (Rate Ratio = 0.88 [0.52, 1.50], p = .64) or withdrawals due to AEs (0.93 [0.24, 3.56], p = .92), but did appear to increase the risk of AEs such as drowsiness, headache and dizziness (1.40 [1.15, 1.69], p < .001). Overall, there has been limited AE reporting from high-dose melatonin studies. Based on this limited evidence, melatonin appears to have a good safety profile. Better safety reporting in future long-term trials is needed to confirm this as our confidence limits were very wide due to the paucity of suitable data.

Melatonin epigenetic potential on testicular functions and fertility profile in varicocele rat model is mediated by Silent information regulator1

BACKGROUND AND PURPOSE

Varicocele is a leading cause of male infertility. Melatonin is a highly pleiotropic neurohormone. We aimed to characterize the melatonin epigenetic potential in varicocele and the involved molecular mechanisms.

EXPERIMENTAL APPROACH

Fifty-two male albino rats were randomly divided into four groups (13 rats each): control (I), melatonin (II), varicocele (III) and melatonin treated varicocele (IV) groups. Left varicocele was induced by partial left renal vein ligation. Reproductive hormones, epididymal sperm functional parameters, testicular 3/17 β-hydroxysteroid dehydrogenases, antioxidant enzymes, malondialdehyde, nicotinamide adenine dinucleotide phosphate oxidase, 8-hydroxy-2'-deoxyguanosine and histopathological/Johnsen's score were evaluated. Flow cytometry and Comet were carried out to explore extent of sperm and testicular DNA damage. Testicular expression of silent information regulator 1 (SIRT1), forkhead transcription factors-class O (type1) (FOXO1), tumour suppressor gene, P53, cation channels of sperm (CatSper) and steroidogenic acute regulatory protein was evaluated by western blot technique. Testicular expression of Bcl-2 and its associated X protein and nuclear factor kappa-light-chain-enhancer of activated B cells were assayed by immunohistochemical staining. Testicular miR-34a expression was quantified by quantitative reverse transcription-polymerase chain reaction.

KEY RESULTS

The varicocele induced testicular histological injury, enhanced oxidative stress, P53-mediated apoptosis, DNA damage and increased testicular miR-34a expression paralleled with down-regulated SIRT1/FOXO axis. Melatonin treatment of varicocele rats displayed antioxidant/anti-apoptotic efficacy and improved reproductive hormones axis, CatSper expression and fertility parameters. MiR-34a/SIRT1/FOXO1 epigenetic axis integrates testicular melatonin mediated intracellular transduction cascades in varicocele.

CONCLUSION AND IMPLICATIONS

Melatonin can be used as an adjuvant therapy to improve varicocele and its complication.

Oxidative Stress-Induced Male Infertility: Role of Antioxidants in Cellular Defense Mechanisms

Male infertility is linked to several environmental and mutagenic factors. Most of these factors, i.e., lifestyle, radiations, and chemical contaminations, work on the fundamental principles of physics, chemistry, and biology. Principally, it may induce oxidative stress (OS) and produce free radicals within the cells. The negative effect of OS may enhance the reactive oxygen species (ROS) levels in male reproductive organs and impair basic functions in a couple's fertility. Evidence suggests that infertile men have significantly increased ROS levels and a reduced antioxidant capacity compared with fertile men. Although, basic spermatic function and fertilizing capacity depend on a delicate balance between physiological activity of ROS and antioxidants to protect from cellular oxidative injury in sperm, that is essential to achieve pregnancy. The ideal oxidation-reduction (REDOX) equilibrium requires a maintenance of a range of ROS concentrations and modulation of antioxidants. For this reason, the chapter focuses on the effects of ROS in sperm functions and the current concepts regarding the benefits of medical management in men with diminished fertility and amelioration of the effect to improve sperm function. Also, this evidence-based study suggests an increasing rate of infertility that poses a global challenge for human health, urging the need of health care professionals to offer a correct diagnosis, comprehension of the process, and an individualized management of the patients.

An In vitro study on the protective effect of melatonin on human sperm parameters treated by cadmium

Background:

Male infertility account for nearly 50% of infertility cases. Cadmium is regarded as a well-known toxic metal for industrial applications; high amounts of cadmium in the human body can result in chronic toxicity. Melatonin as a free radical scavenger has anti-inflammatory, and even anti-cancer and antiapoptotic functions.

Aim:

In this work, we evaluated the protective effect of melatonin on human sperm parameters treated by cadmium.

Study Setting and Design:

This was an experimental study carried out from May to December 2019.

Materials and Methods:

A total of 41 fresh semen samples were collected from fertile men and were divided into 4 groups: (1) control, (2) sperm +25 Nm cd, (3) sperm +25 nM cd +0.1 mM melatonin,(4) sperm +0.1 mM melatonin treated for 60 min. In all groups, semen analysis was performed for motility, viability and DNA fragmentation index (DFI).

Statistical Analysis:

The groups were compared using the ANOVA test.

Results:

The group treated with cadmium showed a significant decrease in rapid and slow motility, and survival rate compared with the control group (P < 0.05). However, the degree of DFI and sperm with non-progressive motility in the group treated with cadmium had a significant increase compared to the control (P < 0.05). The use of melatonin significantly improved sperm parameters such as motility, survival rate and decreased sperm DFI with non-progressive motility.

Conclusions:

The use of melatonin reduces the amount of cadmium damage in human sperm in vitro.

Endocrine disorders and fertility and pregnancy: An update

It is estimated that more and more couples suffer from fertility and pregnancy maintenance disorders. It is associated with impaired androgen secretion, which is influenced by many factors, ranging from genetic to environmental. It is also important to remember that fertility disorders can also result from abnormal anatomy of the reproductive male and female organ (congenital uterine anomalies - septate, unicornuate, bicornuate uterus; acquired defects of the uterus structure - fibroids, polyps, hypertrophy), disturbed hormonal cycle and obstruction of the fallopian tubes resulting from the presence of adhesions due to inflammation, endometriosis, and surgery, abnormal rhythm of menstrual bleeding, the abnormal concentration of hormones. There are many relationships between the endocrine organs, leading to a chain reaction when one of them fails to function properly. Conditions in which the immune system is involved, including infections and autoimmune diseases, also affect fertility. The form of treatment depends on infertility duration and the patient's age. It includes ovulation stimulation with clomiphene citrate or gonadotropins, metformin use, and weight loss interventions. Since so many different factors affect fertility, it is important to correctly diagnose what is causing the problem and to modify the treatment regimen if necessary. This review describes disturbances in the hormone secretion of individual endocrine organs in the context of fertility and the maintenance of pregnancy.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Utility of Antioxidants in the Treatment of Male Infertility: Clinical Guidelines Based on a Systematic Review and Analysis of Evidence

It is widely accepted that oxidative stress plays an important role in the pathophysiology of male infertility and that antioxidants could have a significant role in the treatment of male infertility. The main objectives of this study are: 1) to systematically review the current evidence for the utility of antioxidants in the treatment of male infertility; and 2) propose evidence-based clinical guidelines for the use of antioxidants in the treatment of male infertility. A systematic review of the available clinical evidence was performed, with articles published on Scopus being manually screened. Data extracted included the type of antioxidant used, the clinical conditions under investigation, the evaluation of semen parameters and reproductive outcomes. The adherence to the Cambridge Quality Checklist, Cochrane Risk of Bias for randomized controlled trials (RCTs), CONSORT guidelines and JADAD score were analyzed for each included study. Further, we provided a Strength Weakness Opportunity Threat (SWOT) analysis to analyze the current and future value of antioxidants in male infertility. Of the 1,978 articles identified, 97 articles were included in the study. Of these, 52 (53.6%) were uncontrolled (open label), 12 (12.4%) unblinded RCTs, and 33 (34.0%) blinded RCTs, whereas 44 (45.4%) articles tested individual antioxidants, 31 (32.0%) a combination of several products in variable dosages, and 22 (22.6%) registered antioxidant products. Based on the published evidence, we 1) critically examined the necessity of additional double-blind, randomized, placebo-controlled trials, and 2) proposed updated evidence-based clinical guidelines for antioxidant therapy in male infertility. The current systematic review on antioxidants and male infertility clearly shows that antioxidant supplementation improves semen parameters. In addition, it provides the indications for antioxidant treatment in specific clinical conditions, including varicocele, unexplained and idiopathic male infertility, as well as in cases of altered semen quality.

Varicocoele and oxidative stress: New perspectives from animal and human studies

BACKGROUND

Varicocoele (VCL), one of the main causes of male subfertility, negatively affects testicular function. Due to limited access to human testicular tissue, animal model studies have been used to evaluate molecular and, recently, epigenetic changes attributed to pathophysiology induced by VCL.

OBJECTIVES

This review aims to provide an update on the latest findings regarding the link between VCL-induced biochemical stress and molecular changes in germ cells and spermatozoa. Endocrine and antioxidant status, testicular chaperone-specific hemostasis failure, altered testicular ion balance, metabolic disorders, and altered carbon cycling during spermatogenesis are among the many features that will be presented.

DISCUSSION

Literature review coupled with our own findings suggests that ionic imbalance, hypoxia, hyperthermia, and altered blood flow could lead to severe chronic oxidative and nitrosative stress in patients with VCL leading to defective spermatogenesis and impairment of the integrity of all sperm cell components and compartments down to the epigenetic information they carry.

CONCLUSION

Since oxidative stress is an important feature of the reproductive pathology of VCL, therapeutic strategies such as the administration of appropriate antioxidants could be undertaken as a complementary non-invasive treatment line.

Effects of melatonin supplementation on oxidative stress: a systematic review and meta-analysis of randomized controlled trials

Objectives

Previous studies showed that melatonin supplementation may suppress oxidative stress, however, the results have not been consistent. So, we conducted this meta-analysis to assess the precise relationship between melatonin supplementation and oxidative stress.

Methods

PubMed and Scopus were searched for randomized controlled trials that investigated the effect of melatonin supplementation on oxidative stress up to March 2020. Heterogeneity was assessed by Cochran’s Q test and I-square (I 2) statistic. Data were pooled using the random effect model and standardized mean difference (SMD) was considered as the summary effect size. Also, standard methods were used for assessment of sensitivity analysis and publication bias.

Results

We included 15 related articles and our findings indicated that melatonin supplementation significantly increased total antioxidant capacity (TAC) level (SMD: 1.03, 95% CI: 0.24, 1.81, p=0.011) and reduced protein carbonyl (PCO) (SMD: −1.78, 95% CI: −2.97, −0.58, p=0.004) and malondialdehyde (MDA) levels (SMD: −0.94, 95% CI: −1.48, −0.40, p=0.001). Additionally, there was considerable effect on TAC level by using ≥20 mg/d melatonin and in people under 35 years old. MDA level also decreased using dosage of below 20 mg/d and in people ≥35 years old.

Conclusions

The present study showed a promising effect of melatonin administration for reducing MDA, PCO, and increasing TAC levels. However, further studies especially with more attention to PCO level assessment are needed to confirm the findings of the present study in larger samples on different populations.

Dietary supplements in the management of varicocele-induced infertility: A review of potential mechanisms

Varicocele is a main cause of lower production of spermatozoon and infertility with multiple pathophysiological mechanisms. In the past decades, the use of dietary supplements has significantly increased due to both the modern lifestyle and the food shortages of the industrialised countries. The purpose of this review paper is to collect scientific evidences from basic and clinical studies which support the use of dietary supplements to define the clinical framework for patients with varicocele. In the present review, we used keywords such as dietary supplements, varicocele, male infertility, oxidative stress, DNA fragmentation, sperm parameters to find the proper articles. The standard search biomedical engines were used for seeking the papers. The use of dietary supplements such as minerals, vitamins and antioxidants has an essential role in the prevention and treatment of varicocele by increasing the levels of antioxidant enzymes (e.g. peroxidase, superoxide dismutase and catalase) and decreasing the levels of inflammatory markers (e.g. tumour necrosis factor-α, interleukin-6 and interleukin-1) in testis. According to the results, the dietary supplements may alleviate the spermatogenesis in varicocele patients through different mechanisms such as suppression of stress oxidative and inflammation in testicular tissue.

Protective effect of vitamin E on sperm parameters in rats infected with Candida albicans

Candida albicans is one of the most frequent pathogens present in the reproductive system. The negative in vitro effects of C. albicans on sperm functions have previously been studied. The current study was undertaken to investigate the effects of C. albicans infection in vivo on sperm quality and to evaluate the efficacy of vitamin E administration in rats infected with C. albicans. In this study, 5 days after infection induction, animals were treated with vitamin E for 5 weeks. Thereafter, sperm parameters, lipid peroxidation (LPO), total antioxidant capacity (TAC), hormonal analysis and testis histology were evaluated. Based on the results, sperm parameters and TAC significantly reduced, while LPO and tissue damage increased (p ≤ .05) following the infection. Hormone analysis showed low LH and testosterone levels in serum of the infected rats. Treatment with vitamin E significantly (p ≤ .05) improved sperm quality and testis histology, increased TAC and reduced LPO. In addition, vitamin E administration significantly increased (p ≤ .05) serum LH and testosterone levels. These results clearly indicate that vitamin E is effective in attenuating the adverse effects of C. albicans infection on male fertility and could be used as a complementary treatment for patients who suffer from fertility disorders following C. albicans infection.

Oxidative Stress in Male Infertility: Causes, Effects in Assisted Reproductive Techniques, and Protective Support of Antioxidants

The spermatozoon is a highly specialized cell, whose main function is the transport of the intact male genetic material into the oocyte. During its formation and transit throughout male and female reproductive tracts, sperm cells are internally and externally surrounded by reactive oxygen species (ROS), which are produced from both endogenous and exogenous sources. While low amounts of ROS are known to be necessary for crucial physiological sperm processes, such as acrosome reaction and sperm-oocyte interaction, high levels of those species underlie misbalanced antioxidant-oxidant molecules, generating oxidative stress (OS), which is one of the most damaging factors that affect sperm function and lower male fertility potential. The present work starts by reviewing the different sources of oxidative stress that affect sperm cells, continues by summarizing the detrimental effects of OS on the male germline, and discusses previous studies addressing the consequences of these detrimental effects on natural pregnancy and assisted reproductive techniques effectiveness. The last section is focused on how antioxidants can counteract the effects of ROS and how sperm fertilizing ability may benefit from these agents.

The Importance of Oxidative Stress in Determining the Functionality of Mammalian Spermatozoa: A Two-Edged Sword

This article addresses the importance of oxidative processes in both the generation of functional gametes and the aetiology of defective sperm function. Functionally, sperm capacitation is recognized as a redox-regulated process, wherein a low level of reactive oxygen species (ROS) generation is intimately involved in driving such events as the stimulation of tyrosine phosphorylation, the facilitation of cholesterol efflux and the promotion of cAMP generation. However, the continuous generation of ROS ultimately creates problems for spermatozoa because their unique physical architecture and unusual biochemical composition means that they are vulnerable to oxidative stress. As a consequence, they are heavily dependent on the antioxidant protection afforded by the fluids in the male and female reproductive tracts and, during the precarious process of insemination, seminal plasma. If this antioxidant protection should be compromised for any reason, then the spermatozoa experience pathological oxidative damage. In addition, situations may prevail that cause the spermatozoa to become exposed to high levels of ROS emanating either from other cells in the immediate vicinity (particularly neutrophils) or from the spermatozoa themselves. The environmental and lifestyle factors that promote ROS generation by the spermatozoa are reviewed in this article, as are the techniques that might be used in a diagnostic context to identify patients whose reproductive capacity is under oxidative threat. Understanding the strengths and weaknesses of ROS-monitoring methodologies is critical if we are to effectively identify those patients for whom treatment with antioxidants might be considered a rational management strategy.

Efficacy of antioxidant therapy on sperm quality measurements after varicocelectomy: A systematic review and meta-analysis

Antioxidants were proved to be efficient to improve the quality of spermatozoa after varicocelectomy. We carried out a systematic review and performed a meta-analysis to evaluate the efficacy of antioxidant therapy in sperm parameters' quality after varicocelectomy during 3 or 6 months' treatment cycle. During research, randomised controlled trials were searched by MEDLINE, EMBASE and the Cochrane Controlled Trials Register, and necessary parameters were compared between two groups after varicocelectomy. Finally, six studies including 576 patients were included in our meta-analysis. As for sperm parameters, significant improvements of sperm concentration (p < .0001), sperm motility (p = .03), progressive sperm motility (p < .00001) and sperm morphology (p < .00001) were existed in antioxidant group 3 months after varicocelectomy. With regard to the 6 months' outcomes, sperm parameters were improved as well except sperm motility (p = .72) and progressive sperm motility (p = .57). Referring to pregnancy rate, no significant difference was existed between two groups (p = .36), and the FSH level of antioxidant group was lower than placebo group 3 or 6 months after varicocelectomy (3 months, p = .02; 6 months, p = .03). In conclusion, compared with the placebo, the antioxidant therapy after varicocelectomy can improve the quality of sperm parameters and construct a favourable living condition for spermatozoa by reducing FSH level.