The incriminating role of reactive oxygen species in idiopathic male infertility: an evidence based evaluation

Tetracarpidium conophorum ameliorates oxidative reproductive toxicity induced by ethanol in male rats

Background

Tetracarpidium conophorum (Mull. Arg.) Hutch. & Dalz is one of the many medicinal plants used for ages in folklore as male fertility enhancers. The current study evaluates the effect of the plant leaf extract on alcohol - induced reproductive toxicity in male rats.

Methods

Thirty rats were randomly divided into six groups of five animals each; Group 1 (positive control) received normal saline only; Group 2 (ethanol alone) were given only 30 % ethanol orally at 7 ml/kg body weight per day, thrice in a week; Group 3, 4, 5 were given ethanol and co-treated with 50 mg/kg, 500 mg/kg and 1000 mg/kg body weight of leaf extract respectively while Group 6 were given ethanol and co-treated with a fertility drug, clomiphene citrate. All the drugs were given daily and the experiment lasted for twenty one consecutive days.

Results

Alcohol ingestion resulted in a significant (p < 0.05) decrease in water, food intake and marked elevation of lipid peroxidation as assessed by the accumulation of malondialdehyde (MDA) in the reproductive tissues. Precisely, MDA level was elevated in the testis, epididymis, seminal vesicle and prostate gland by 81 %, 63 %, 95 % and 91 %, respectively. Furthermore, levels of total protein, reduced glutathione (GSH), vitamin C and activities of antioxidant enzymes in the reproductive tissues were significantly (p < 0.0001) reduced in ethanol-ingested rats. Interestingly, co-administration of T. conophorum with ethanol led to almost complete inhibition of lipid peroxidation thereby enhancing antioxidant status of the reproductive tissues.

Conclusion

Overall, T. conophorum ameliorates oxidative reproductive toxicity induced by ethanol in male rats and its ameliorative effect comparable well with the fertility drug, clomiphene citrate.

Utility of antioxidants during assisted reproductive techniques: an evidence based review

Assisted reproductive technology (ART) is a common treatment of choice for many couples facing infertility issues, be it due to male or female factor, or idiopathic. Employment of ART techniques, however, come with its own challenges as the in vitro environment is not nearly as ideal as the in vivo environment, where reactive oxygen species (ROS) build-up leading to oxidative stress is kept in check by the endogenous antioxidants system. While physiological amounts of ROS are necessary for normal reproductive function in vivo, in vitro manipulation of gametes and embryos exposes these cells to excessive ROS production either by endogenous or exogenous environmental factors. In this review, we discuss the sources of ROS in an in vitro clinical setting and the influence of oxidative stress on gamete/embryo quality and the outcome of IVF/ICSI. Sources of ROS and different strategies of overcoming the excessive generation of ROS in vitro are also highlighted. Endogenously, the gametes and the developing embryo become sources of ROS. Multiple exogenous factors act as potential sources of ROS, including exposure to visible light, composition of culture media, pH and temperature, oxygen concentration, centrifugation during spermatozoa preparation, ART technique involving handling of gamete/embryo and cryopreservation technique (freeze/thawing process). Finally, the use of antioxidants as agents to minimize ROS generation in the in vitro environment and as oral therapy is highlighted. Both enzymatic and non-enzymatic antioxidants are discussed and the outcome of studies using these antioxidants as oral therapy in the male or female or its use in vitro in media is presented. While results of studies using certain antioxidant agents are promising, the current body of evidence as a whole suggests the need for further well-designed and larger scale randomized controlled studies, as well as research to minimize oxidative stress conditions in the clinical ART setting.

Role of poly(ADP-ribose) polymerases in male reproduction

Poly(ADP-ribose) polymerases (PARPs) are a family of enzymes involved in a wide variety of biological processes, including DNA repair and maintenance of genomic stability following genotoxic stress, and regulates the expression of various proteins at the transcriptional level as well as replication and differentiation. However, excessive activation of PARP has been shown to contribute to the pathogenesis of several diseases associated with oxidative stress (OS), which has been known to play a fundamental role in the etiology of male infertility. Based on the degree and type of the stress stimulus, PARP directs cells to specific fates (such as, DNA repair vs. cell death). A large volume of accumulated evidence indicates the presence of PARP and its homologs in testicular germ line cells and its activity may offer a key mechanism for keeping DNA integrity in spermatogenesis. On the other hand, a possible role of PARP overactivation in OS-induced male reproductive disorders and in human sperm is gaining significance in recent years. In this review, we focus on the findings about the importance of PARP-1 and PARP-2 in male reproduction and possible involvement of PARP overactivation in various clinical conditions associated with male infertility.

Effect of oxidative stress on male reproduction

Infertility affects approximately 15% of couples trying to conceive, and a male factor contributes to roughly half of these cases. Oxidative stress (OS) has been identified as one of the many mediators of male infertility by causing sperm dysfunction. OS is a state related to increased cellular damage triggered by oxygen and oxygen-derived free radicals known as reactive oxygen species (ROS). During this process, augmented production of ROS overwhelms the body's antioxidant defenses. While small amounts of ROS are required for normal sperm functioning, disproportionate levels can negatively impact the quality of spermatozoa and impair their overall fertilizing capacity. OS has been identified as an area of great attention because ROS and their metabolites can attack DNA, lipids, and proteins; alter enzymatic systems; produce irreparable alterations; cause cell death; and ultimately, lead to a decline in the semen parameters associated with male infertility. This review highlights the mechanisms of ROS production, the physiological and pathophysiological roles of ROS in relation to the male reproductive system, and recent advances in diagnostic methods; it also explores the benefits of using antioxidants in a clinical setting.

The alteration of protein profile induced by cigarette smoking via oxidative stress in mice epididymis

Smoking is associated with a declining quality of semen. The aim of this study was to screen and investigate the differential expression of proteins extracted from the epididymis of mice exposed daily with cigarette smoke. Using MALDI-TOF-MS analysis, we found that the protein profile of the mouse epididymis was altered by cigarette smoking and identified 27 proteins from the most abundant and differentially expressed spots in the 2-DE gels of epididymal samples. These proteins were classified into groups according to their functions such as energy metabolism, reproduction and structural molecule activity. Through pathway analysis, these proteins were associated with the glutathione metabolism and protein processing in the endoplasmic reticulum. These results showed that the epididymis may experience oxidative stress following cigarette smoke exposure, which was confirmed using immunohistochemistry. We determine that cigarette smoking can induce oxidative stress in the mouse epididymis, which may cause protein profile altering, thereby impairing epididymis function, and leading to a decline in semen quality.

Mystery of idiopathic male infertility: is oxidative stress an actual risk?

OBJECTIVE

To study the role of oxidative stress in sperm dysfunction in Turkish idiopathic infertile men.

DESIGN

Prospective study.

SETTING

Medical laboratory.

PATIENT(S)

Semen samples from 28 idiopathic infertile men and 14 fertile men.

INTERVENTION(S)

Sperm DNA fragmentation and reactive oxygen species (ROS) formation were assayed with the terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) test and 2',7'-dichlorodihydrofluorescein, respectively. Seminal plasma protein carbonyl groups (PC), nitrotyrosine (NT), malondialdehyde (MDA), and total thiol (SH) levels and ferric reducing antioxidant power (FRAP) were determined.

MAIN OUTCOME MEASURE(S)

Sperm DNA fragmentation in relation to ROS formation and seminal plasma oxidative parameters.

RESULT(S)

The number of TUNEL-positive spermatozoa from idiopathic infertile men was higher than from fertile men, and ROS formation was increased as well in infertile males. A positive correlation was detected between TUNEL-positive cells and ROS content. Seminal plasma MDA, PC, and NT levels were elevated in idiopathic infertile males. No difference was observed in the total SH content and FRAP. Seminal plasma MDA levels correlated positively with both NT and PC levels. Positive correlations were detected between DNA fragmentation and MDA, NT, and PC of seminal plasma, and between sperm ROS content and MDA levels.

CONCLUSION(S)

The results of this study support the presence of oxidative stress in sperm dysfunction in Turkish idiopathic infertile men.

Cost-effective diagnosis of male oxidative stress using the nitroblue tetrazolium test: useful application for the developing world

Seminal oxidative stress plays an important role in male factor infertility (MFI), worldwide. A study was thus undertaken for the first time to establish seminal reactive oxygen species (ROS) as a clinical marker of MFI in a cohort of Sri Lankan males. The nitro blue tetrazolium (NBT) assay for ROS estimation and modified Endtz test for detecting leucocytes were carried out on semen samples (N = 102) of subfertile males. Age-matched individuals (N = 30) with proven past paternity served as controls. Significantly higher ROS production was evident in individuals with asthenozoospermia and unexplained infertility (Mann-Whitney U-test, P = 0.000), than in the fertile and the other subfertile groups tested. Receiver operating characteristic plot analysis established cut-off points of 40.57 and 42.02 μg formazan/10(7) spermatozoa for ROS to distinguish fertile males from asthenozoospermics (71.4% sensitivity: 70% specificity; AUC = 0.82), and from unexplained infertile males (74.1 % sensitivity: 73.3% specificity; AUC = 0.85) respectively. As ROS appear to be a potential marker of male infertility, it is imperative to validate this test as a simple, cost-effective hence a widely accessible diagnostic tool to be included in MFI investigations in the developing world.

The effects of oxidative stress on female reproduction: a review

Oxidative stress (OS), a state characterized by an imbalance between pro-oxidant molecules including reactive oxygen and nitrogen species, and antioxidant defenses, has been identified to play a key role in the pathogenesis of subfertility in both males and females. The adverse effects of OS on sperm quality and functions have been well documented. In females, on the other hand, the impact of OS on oocytes and reproductive functions remains unclear. This imbalance between pro-oxidants and antioxidants can lead to a number of reproductive diseases such as endometriosis, polycystic ovary syndrome (PCOS), and unexplained infertility. Pregnancy complications such as spontaneous abortion, recurrent pregnancy loss, and preeclampsia, can also develop in response to OS. Studies have shown that extremes of body weight and lifestyle factors such as cigarette smoking, alcohol use, and recreational drug use can promote excess free radical production, which could affect fertility. Exposures to environmental pollutants are of increasing concern, as they too have been found to trigger oxidative states, possibly contributing to female infertility. This article will review the currently available literature on the roles of reactive species and OS in both normal and abnormal reproductive physiological processes. Antioxidant supplementation may be effective in controlling the production of ROS and continues to be explored as a potential strategy to overcome reproductive disorders associated with infertility. However, investigations conducted to date have been through animal or in vitro studies, which have produced largely conflicting results. The impact of OS on assisted reproductive techniques (ART) will be addressed, in addition to the possible benefits of antioxidant supplementation of ART culture media to increase the likelihood for ART success. Future randomized controlled clinical trials on humans are necessary to elucidate the precise mechanisms through which OS affects female reproductive abilities, and will facilitate further explorations of the possible benefits of antioxidants to treat infertility.

What every gynecologist should know about male infertility: an update

PURPOSE

Our article reviews the evolving concepts in the field of male infertility for gynecologists and other health professionals involved in the care of men and women experiencing difficulty in having a child. The increased knowledge will help in the better management and treatment of infertile couples.

METHODS

Review of literature through Pubmed, Science Direct, Online Library.

RESULTS

Gynecologists are often the first healthcare providers to assess an infertile couple. Because half of all infertility problems stem from male factors, it is crucial for the gynecologist to remain updated on the main conditions that cause male infertility as well as current diagnostic tools and treatment options, including conventional strategies and assisted reproductive techniques.

CONCLUSIONS

Extraordinary advances have been achieved in the field of male infertility over the past several years and many old concepts are now challenged. Therefore, it is imperative that male infertility physicians should update the gynecologists about the recent advances in the work-up of infertile men in terms of diagnosis and management. Such convention will help improve the standards of care for the infertile couple and enhance the cooperation between male and female reproductive endocrinologists.

Elevation of both reactive oxygen species and antioxidant enzymes in vein tissue of infertile men with varicocele

OBJECTIVE

To compare reactive oxygen species (ROS) and antioxidants in internal spermatic vein tissue of men with varicocele and a control group with inguinal hernia. Also to compare the levels of oxidants and antioxidants in infertile and fertile men with varicocele.

PATIENTS AND METHODS

48 varicocele patients and 12 non-varicocele inguinal hernia patients participated in this study. The varicocele group was again divided into two groups--fertile men with varicocele and infertile men with varicocele. Internal spermatic vein tissue samples were obtained. The level of the malondialdehyde (MDA), an indicator of oxidative stress, and the activities of antioxidant enzymes (defense systems) against oxidative stress such as superoxide dismutase (SOD) and catalase (CAT) were estimated in these tissue samples.

RESULTS

The mean level of MDA in the varicocele group was significantly higher than in the hernia group, whereas the levels of antioxidants (SOD and CAT) were significantly lower in the varicocele group than in the hernia group. When compared with the subgroups of the varicocele group, the MDA levels and SOD and CAT activities were significantly higher in the infertile varicocele group than in the fertile varicocele group.

CONCLUSIONS

Antioxidant enzyme levels generally decrease due to a high consumption in varicocele patients. On the contrary, in our study both MDA and antioxidant enzymes increased in the internal spermatic venous wall of infertile varicocele patients. This situation may be explained by an adaptation against oxidative stress in varicocele, which could be defined as a chronic process.

Sperm DNA integrity assays: diagnostic and prognostic challenges and implications in management of infertility

Sperm is not a simple carrier of paternal genetic information but its role extends clearly beyond fertilization. Integrity of sperm genome is an essential pre-requisite for birth of healthy offspring and evaluation of sperm should entail DNA integrity analysis. DNA integrity analysis is a better diagnostic and prognostic marker of sperm reproductive potential. Conventional semen analysis emphasizes on sperm concentration, viability, motility and morphology and has been proven to be a poor indicator of reproductive potential and pregnancy outcome. To overcome the drawbacks associated with conventional semen analysis more useful fertility tests and molecular biomarkers have been explored. Among the different tests which have evolved for assessing the sperm reproductive potential, tests for sperm DNA quality are most promising. Sperm DNA damage has been closely associated with numerous indicators of reproductive health including fertilization, embryo quality, implantation, spontaneous abortion, congenital malformations and childhood diseases. It therefore has great potential as a prognostic test for both in vitro and in vivo conception. This review presents an updated account of tests that have better diagnostic and prognostic implications in the evaluation of sperm DNA damage. The basic principles, outline of methodology, advantage, disadvantage, clinical significance of each technique and implications of these tests have been discussed. The logistics of each test with respect to available resources and equipment in an andrology laboratory, the feasibility of performing these tests in routine diagnostic workup of infertile men and the opportunities and challenges provided by DNA testing in male fertility determination are also presented.

Luteinising hormone β-subunit gene Gly102Ser variant and oxidative stress biomarkers in Egyptian infertile males

The aim of the present study was to evaluate the association of Glycine102Serine molecular variant of luteinising hormone (LH) β-subunit gene with infertility in Egyptian males and to assess the impact of oxidative stress in association with Glycine102Serine molecular variant on male infertility. Fifty men with idiopathic oligozoospermia were enrolled in the study. The control group consisted of 39 men with normal semen parameters and proven fertility. Variable oxidative status markers were evaluated. Glycine102Serine variant was investigated using restriction fragment length polymorphism-polymerase chain reaction. The study concluded that Glycine102Serine variant of LH β-subunit gene is relatively common among infertile Egyptian males and might be implicated in some Egyptian infertility cases. In addition, the association of this variant, in some cases, with disturbed oxidative status (decreased seminal plasma antioxidants' level and increased sperm lipid peroxidation) probably have a significant role in accentuation of infertility in those particular cases.