Sperm Oxidative Stress Research Articles

Sperm Oxidative Stress during In Vitro Manipulation and Its Effects on Sperm Function and Embryo Development.

Reactive oxygen species (ROS) generated at low levels during mitochondrial respiration have key roles in several signaling pathways. Oxidative stress (OS) arises when the generation of ROS exceeds the cell’s antioxidant scavenging ability and leads to cell damage. Physiological ROS production in spermatozoa regulates essential functional characteristics such as motility, capacitation, acrosome reaction, hyperactivation, and sperm-oocyte fusion. OS can have detrimental effects on sperm function through lipid peroxidation, protein damage, and DNA strand breakage, which can eventually affect the fertility of an individual. Substantial evidence in the literature indicates that spermatozoa experiencing OS during in vitro manipulation procedures in human- and animal-assisted reproduction are increasingly associated with iatrogenic ROS production and eventual impairment of sperm function. Although a direct association between sperm OS and human assisted reproductive techniques (ART) outcomes after in vitro fertilization (IVF) and/or intracytoplasmic sperm injection (ICSI) is still a matter of debate, studies in animal models provide enough evidence on the adverse effects of sperm OS in vitro and defective fertilization and embryo development. This review summarized the literature on sperm OS in vitro, its effects on functional ability and embryo development, and the approaches that have been proposed to reduce iatrogenic sperm damage and altered embryonic development.

Clinical observation of herb-separated moxibustion on segmental conception vessel combined with low-frequency TEAS for asthenospermia and oligospermia

To observe the clinical effect of herb-separated moxibustion on segmental conception vessel combined with low-frequency transcutaneous electrical acupoint stimulation (TEAS) for asthenospermia and oligospermia. A total of 105 patients with asthenospermia and oligospermia were randomly divided into a combination group, a TEAS group and a medication group, 35 cases in each one. In the medication group, vitamin E capsules, coenzyme Q10 capsules，Wuzi Yanzong pills were taken. In the TEAS group, TEAS was applied at Shenshu (BL 23) and Pishu (BL 20), 2 Hz in frequency, 10-15 mA in intensity, once every 2 days, 30 min each time.On the base of the treatment as the TEAS group, herb-separated moxibustion on segmental conception vessel [Shenque (CV 8) to Zhongji (CV 3)] was applied in the combination group, once every 10 days. A total of 3 months were required in the 3 groups.Before treatment and 2, 3 months into treatment, the semen routine indexes (concentration, normal morphology rate, sperm motility), seminal plasma contents of superoxide dismutase (SOD) and malondialdehyde (MDA) and TCM syndrome score were observed in the 3 groups, and the clinical efficacy was evaluated. Compared before treatment, except for the sperm morphology 2 months into treatment in the medication group, the semen routine indexes 2, 3 months into treatment were improved in the 3 groups (P<0.01), and the semen routine indexes 2, 3 months into treatment in the combination group were superior to the medication group and the TEAS group (P<0.01). Compared before treatment, the seminal plasma contents of SOD were increased and MDA were decreased 2, 3 months into treatment in the 3 groups (P<0.01), and the changes of the combination group were larger than the medication group and the TEAS group (P<0.01). Compared before treatment, the TCM syndrome scores 2, 3 months into treatment in the combination group, and 3 months into treatment in the medication group and the TEAS group were decreased (P<0.01). The TCM syndrome scores 2, 3 months into treatment in the combination group were lower than the medication group and the TEAS group (P<0.01). The total effective rates in the combination group, the medication group and the TEAS group were 85.7% (30/35), 68.6% (24/35) and 65.7% (23/35), the clinical efficacy of the combination group was higher than the medication group and the TEAS group (P<0.05). Herb-separated moxibustion on segmental conception vessel combined with low-frequency TEAS can improve semen routine, reduce sperm oxidative stress damage for patients with asthenospermia and oligospermia, and the clinical efficacy is better than the medication and TEAS.

Sperm oxidative stress: clinical significance and management

Oxidative stress is one of the leading causes of sperm dysfunction. Excessive amounts of reactive oxygen species can damage sperm membranes and disrupt their DNA integrity, which affects not only the likelihood of getting pregnant naturally, but also the clinical outcomes of assisted reproductive technologies and the risk of miscarriage. Sperm cells are extremely vulnerable to oxidative stress, given the limited functional reserve of their antioxidant systems and the DNA repair apparatus. Lifestyle factors, most of which are modifiable, often trigger generation of reactive oxygen species. Both the lifestyle modification and use of antioxidant dietary supplements are adequate and compatible ways to combat male oxidative stress-associated infertility. The search for other internal and external sources of reactive oxygen species, the identification of the etiology of oxidative stress and treatment of respective diseases are necessary for the successful regulation of redox processes in the male reproductive system in clinical practice, which is required not only to overcome infertility, but also to prevent induced epigenetic disorders in subsequent generations. The article presents the analysis of the molecular mechanisms of male idiopathic infertility. The authors provide an overview of how to prevent oxidative stress as one of the causes of subfebrile fever. The article provides an overview of modern therapeutics, as well as the options for eliminating the consequences of the effect of reactive oxygen species on spermatogenesis and male reproductive system in general.

Impact of the Vegan Diet on Sperm Quality and Sperm Oxidative Stress Values: A Preliminary Study.

Background:Insufficient nutrition and inappropriate diet have been related to many diseases. Although the literature confirms the hypothesis that particular nutritional factors can influence the quality of semen, until today, there are no specific dietary recommendations created for infertile males. Since the male contribution to the fertility of a couple is crucial, it is of high importance to determine the dietary factors that can affect male fertility.Aim:The aim of the present study was to evaluate differences in sperm quality parameters, sperm oxidative stress values and sperm acrosome reaction between vegan diet consumers and non-vegans.Setting and Design:Prospective study in a University Medical School.Materials and Methods:The present study was undertaken to evaluate the sperm quality parameters of vegan diet consumers (10 males who had a strictly vegetable diet with no animal products) and compare them with non-vegans (10 males with no diet restrictions). Semen quality was assessed following the World Health Organization (2010) criteria. Acrosome and DNA integrity has been evaluated using the immunofluorescence technique.Statistical Analysis:All variables were analysed by IBM SPSS version 24. Mean differences among groups were compared by Mann–Whitney U-test.Results:Obtained results showed that total sperm count (224.7 [117–369] vs. 119.7 [64.8–442.8]; P = 0.011) and the percentage of rapid progressively motile sperm were significantly higher in the vegan group compared with the non-vegan group (1 [0–7] vs. 17.5 [15–30]; P < 0.0001). Furthermore, the oxidation-reduction potential (0.4 [0.3–0.9] vs. 1.5 [0.6–2.8]; P < 0.0001) and the proportion of spermatozoon with DNA damage (14.7 [7–33.5] vs. 8.2 [3–19.5]; P = 0.05) were significantly higher in the non-vegan group in comparison to the vegan group.Conclusions:Results obtained in this study provide additional evidence about the favourable effect of a plant-based diet on sperm parameters. To confirm our preliminary findings, further studies including larger cohorts are warranted.

Sperm DNA fragmentation: etiology, pathogenesis, the influence on reproductive function

The literature review of sperm DNA fragmentation is evaluated. Russian and foreign literary data over the past 10 years, including fundamental researching of the evaluation of the gametes genome integrity, are analyzed. The main etiological factors and the possible reasons of the DNA breaks formation on the different stages of spermatogenesis are described. The influence of the sperm oxidative stress reaction to the DNA integrity is analyzed. The relationship between DNA fragmentation of spermatozoa pregnancy and live birth rates in the assisted reproductive techniqueare noted. Risk of the recurrent pregnancy losses in male infertility cases with the sperm DNA damage is presented. Review confirms the significant prognostic value of sperm DNA fragmentation detection in infertility cases. Further studies in evaluation of pathogenesis of sperm DNA have a clinical interest to reproductive health physicians.

Seminal Plasma Proteomic Biomarkers of Oxidative Stress.

The prevalence of idiopathic male infertility is high, up to 75% of patients with abnormal sperm parameters. Hence, the research of its causes is mandatory. Oxidative stress (OS) can be responsible for male infertility in 30–80% of cases. In recent years, seminal plasma (SP) proteomics has developed as a useful tool to provide biomarkers of specific diseases. This systematic review aims to collect the available evidence on the changes of SP proteome in patients exposed to OS to provide possible SP biomarkers of sperm OS. To accomplish this, the following keyterms “seminal fluid proteome”, “seminal plasma proteome”, “oxidative stress”, and “sperm oxidative stress” were used and 137 records were found. Among these, 17 were finally included. Nine proteins involved with OS were found overexpressed in patients with OS. Twenty-three proteins were found differentially expressed in patients with clinical conditions associated with OS, such as varicocele, male accessory gland infection/inflammation, cigarette smoke, and obesity. These proteins do not seem to overlap among the clinical conditions taken into account. We speculate that specific SP proteins may mediate OS in different clinical conditions. Altogether, these results suggest that proteomics could help to better understand some of the molecular mechanisms involved in the pathogenesis of infertility. However, further studies are needed to identify potential biomarkers of male infertility with valuable clinical significance.

Changes in miRNA levels of sperm and small extracellular vesicles of seminal plasma are associated with transient scrotal heat stress in bulls

Scrotal heat stress affects spermatogenesis and impairs male fertility by increasing sperm morphological abnormalities, oxidative stress and DNA fragmentation. While sperm morpho-functional changes triggered by scrotal heat stress are well described, sperm molecular alterations remain unknown. Recently, spermatozoa were described as accumulating miRNAs during the last steps of spermatogenesis and through epididymis transit, mainly by communication with small extracellular vesicles (sEVs). Herein, the aim was to investigate the impact of scrotal heat stress in miRNAs profile of sperm, as well as, seminal plasma sEVs. Six Nelore bulls (Bos indicus) were divided into two groups: Control (CON; n = 3) and Scrotal Heat Stress (SHS; n = 3; scrotal heat stressed during 96 h by scrotal bags). The day that the scrotal bags were removed from SHS group was considered as D0 (Day zero). Seminal plasma sEVs were isolated from semen samples collected seven days after heat stress (D+7) to evaluate sEVs diameter, concentration, and 380 miRNA levels. Sperm morpho-functional features and profile of 380 miRNAs were evaluated from semen collected 21 days after heat stress (D+21). As a control, sEVs and sperm were analyzed seven days before heat stress (D-7). Only semen parameters that were not significantly different (P > 0.05) among bulls on D-7 were addressed on D+7 and D+21. While no alterations in diameter and concentration were detected in sEVs on D+7 between CON and SHS groups, three sEVs-miRNAs (miR-23b-5p, −489 and −1248) were down-regulated in SHS bulls compared to CON on D+7; other three (miR-126-5p, −656 and −1307) displayed a tendency (0.05 < P < 0.10) to be altered. Sperm oxidative stress was higher, and the level of 21 sperm miRNAs was altered (18 down-, 3 up-regulated) in SHS bulls compared to CON on D+21. Functional analysis indicated that target genes involved in transcription activation, as well as cell proliferation and differentiation were related to the 18 down-regulated sperm miRNAs (miR-9-5p, −15a, −18a, −20b, −30a-5p, −30b-5p, −30d, −30e-5p −34b, −34c, −106b, -126-5p, −146a, −191, −192, −200b, −335 and −449a). Thus, the scrotal heat stress probably impacted testicular and epididymis functions by reducing the levels of a substantial proportion of sEVs and sperm miRNAs. Our findings suggest that miR-126-5p was possibly trafficked between sEVs and sperm and provide new insights on the mechanism by which sperm acquire miRNAs in the last stages of spermatogenesis and sperm maturation in cattle.

Male infertility: before and after the era of SARS-CoV-2

It has been found that men are infected with the coronavirus 1.5 times more often than women, but at the same time 95% of them have mild infection. There are questions that require a scientific explanation: why are men infected more often and more susceptible than women, does the virus cross the blood-testicular barrier, can it be found in the seminal fluid, does SARS-CoV-2 have an effect on the production of androgens, is the testicle affected and what are the consequences of this damage, what is the direct effect of a virus and virus-associated problems (such as social problems, isolation, quarantine, psychological problems, sedentary lifestyle, etc.) primarily on sexual function, sexual behaviour and reproduction in general? The review article examines the SARS-CoV-2 pandemic-associated situation in 2020 and its effect on the men’s health. The article provides data on epidemiology, aspects of pathogenesis, features of new coronavirus infection in men. The authors announced the international reproduction associations (ASRM, ESHRE, RAHR) recommendations for the implementation of assisted reproductive technology (ART) programs in the era of the pandemic. Different points of view on the effect of testosterone on the disease incidence in men are presented. The importance of sperm oxidative stress and antioxidant therapy for male infertility has been shown. The tasks of an international project for the study of SARS-CoV-2 coronavirus infection and its consequences on men’s health are outlined. An invitation to collaboration with domestic and foreign specialists in the field of urology and andrology under the aegis of the National Medical Research Center of Obstetrics, Gynecology and Perinatology named after Academician V.I. Kulakov of the Ministry of Health of the Russian Federation has been published.

Determination of NRF2 and GSTM1 Expression and Biomarkers of Oxidative Stress on Smoking and Nonsmoking Sperm: A Pilot study

Background and Aims: Smoking has an influence on different semen parameters. It is regarded as a risk factor for infertility. This study aims to evaluate the effect of smoking cigarettes on the expression of nuclear factor erythroid 2-related factor 2 (NRF2) and glutathione S-transferase Mu 1 (GSTM1) genes and biomarkers of oxidative stress in sperm. Materials and Methods: A case-control study was conducted on 15 men smoker (case) and 15 men nonsmokers (control) who had referred to infertility clinics in Isfahan, Iran. After sampling and analysis of semen quality parameters, gene expression of NRF2 and GSTM1 was determined using a Real time-polymerase chain reaction instrument. The lipid peroxidation and total antioxidant capacity (TAC) were evaluated by colorimetric methods. Results: Sperm concentration and their progressive motility in smokers were significantly lower than the nonsmoker population (p&lt;0.001). In addition, the lipid peroxidation level increased and TAC level (p&lt;0.01) as well as gene expression of NRF2 (p&lt;0.05) and GSTM1 (p&lt;0.01) decreased compared to control groups. Conclusions: Our data demonstrated that the NRF2 and GSMT1 expressions are significantly lower in human males with low sperm motility and correlated with specific sperm quality parameters.

Capsaicin improves sperm quality in rats with experimental varicocele.

Capsaicin is the main capsaicinoid in chilli peppers that have numerous biological and pharmaceutical roles in the body such as antioxidant, anti-inflammatory, anticarcinogenic, analgesic, counterirritant and antiarthritic properties. Numerous studies have shown increased oxidative stress in men with varicocele that is caused by dilation of the spermatic vein and increase of testicular temperature. Therefore, we aimed to assess the effect of Capsaicin on sperm parameters in rats with experimental varicocele. At first, we induced varicocele in 30 Wistar rats and, verify varicocele model only in 10 rats by assessment of sperm parameters, oxidative stress, DNA damage and persistent histone after 2months. Of the remaining 20 varicocelised rats, half of them were treated with 2.5mg/kg Capsaicin for two months and the other half served as control. Then, sperm tests were assessed, and the results showed that Capsaicin can restore the mean of sperm oxidative stress (38.78±3.75 versus 58.37±4.34; p<.05), sperm concentration (60.14±7.66 versus 34.87±5.78; p<.05) and motility (62.43±3.10 versus 41.22±5.11; p<.05) in varicocelised rats treated with Capsaicin compared to varicocelised rats that were not treat. Therefore, Capsaicin possibly with reduction of oxidative stress level could improve mean of sperm concentration and motility in varicocele condition.

Use of a male antioxidant nutraceutical is associated with superior live birth rates during IVF treatment.

Oxidative stress is prevalent among infertile men and is a significant cause of sperm DNA damage. Since sperm DNA damage may reduce embryo quality and increase miscarriage rates, it is possible that untreated sperm oxidative stress may impair in vitro fertilization (IVF) live birth rates. Given that the antioxidant Menevit is reported to reduce sperm DNA damage, it was hypothesized that men's consumption of this supplement may alter IVF outcomes. Therefore, a retrospective cohort study was conducted analyzing outcomes for couples undergoing their first fresh embryo transfer. Men were classified as controls if they were taking no supplements, health conscious controls if taking “general health” supplements, or Menevit users. Men with karyotype abnormalities, or cycles using donated, frozen and surgically extracted sperm were excluded. Among the final study cohort of 657 men, live birth rates were significantly higher in Menevit users than controls (multivariate adjusted odds ratio [OR]: 1.57, 95% confidence interval [CI]: 1.01–2.45, P = 0.046), but not between controls taking no supplements and those using general health supplements, thereby suggesting that potential health conscious behavior in supplement users is unlikely responsible for the superior outcomes in Menevit users. Interestingly, in a post hoc sensitivity analysis, live birth rates among Menevit users were statistically superior to controls for lean men (OR: 2.73, 95% CI: 1.18–6.28; P = 0.019), not their overweight/obese counterparts (OR: 1.29, 95% CI: 0.75–2.22, P = 0.37). The results of this large cohort study therefore support a positive association between men's use of the Menevit antioxidant during IVF treatment and live birth rates, especially in lean individuals.

The Relationship between Sperm Oxidative Stress Alterations and IVF/ICSI Outcomes: A Systematic Review from Nonhuman Mammals.

Achieving high embryo quality following IVF and ICSI procedures is a key factor in increasing fertility outcomes in human infertile couples. While the male factor is known to underlie infertility in about 50% of cases, studies performed in human infertile couples have not been able to define the precise effect of sperm affectations upon embryo development. This lack of consistency is, in most cases, due to the heterogeneity of the results caused by the multiple male and female factors that mask the concrete effect of a given sperm parameter. These biases can be reduced with the use of animal gametes, being a good approach for basic researchers to design more homogeneous studies analyzing the specific consequences of a certain affectation. Herein, we conducted a systematic review (March 2020) that assessed the relationship between sperm oxidative stress alterations and IVF/ICSI outcomes in nonhumans mammals. The review was conducted according to PRISMA guidelines and using the MEDLINE-PubMed and EMBASE databases. Thirty articles were included: 11 performed IVF, 17 conducted ICSI, and two carried out both fertilization methods. Most articles were conducted in mouse (43%), cattle (30%) and pig models (10%). After IVF treatments, 80% of studies observed a negative effect of sperm oxidative stress on fertilization rates, and 100% of studies observed a negative effect on blastocyst rates. After ICSI treatments, a positive relationship of sperm oxidative stress with fertilization rates (75% of studies) and with blastocyst rates (83% of studies) was found. In conclusion, the present systematic review shows that sperm oxidative stress is associated with a significant reduction in fertilization rates and in vitro embryo development.

Follicle-Stimulating Hormone Treatment and Male Idiopathic Infertility: Effects on Sperm Parameters and Oxidative Stress Indices according to FSHR c. 2039 A/G and c. -29 G/A Genotypes.

Scientific evidence shows that the administration of follicle-stimulating hormone (FSH) to infertile patients with normal serum FSH concentrations improves sperm parameters in oligozoospermic men. The aim of this study was to evaluate the effects of highly purified urofollitropin (hpFSH) on conventional and bio-functional sperm parameters and on oxidative stress indices in patients with idiopathic infertility. We also evaluated the response to hpFSH on these parameters in relationship to FSHR c. 2039 A/G and FSHR c. -29 G/A genotypes. A prospective longitudinal study was conducted on 42 patients with idiopathic male infertility, 23 of whom underwent to FSHR c. 2039 A/G and FSHR c. -29 G/A genotyping. Each patient was asked to collect two semen samples before and after administration of 150 IU hpFSH three times a week for 16 weeks. Patients were divided into responders or non-responders based on whether their total sperm count had at least doubled or was less than double at the end of treatment, respectively. Responders showed a significantly higher semen volume, sperm concentration, spermatids, and leukocytes. Non-responders had a significant decrease of the percentage of spermatozoa in early apoptosis after hpFSH administration. Oxidative stress indexes did not differ significantly after FSH administration in both groups. Conventional and bio-functional sperm parameters did not differ in patients with FSHR c. 2039 GG and AA genotypes, and FSHR c. -29 GG genotype both before and after FSH administration. The FSHR c. 2039 and FSHR -29 G/A genotypes and allelic distribution did not differ between responders and non-responders. FSH showed to be capable of ameliorating sperm parameters in about half patients treated, therefore it may be helpful in patients with idiopathic infertility.

Oxidative stress in cryopreserved semen of sex-reversed female and normal male rainbow trout

The aim of the current study was to determine the sperm quality of sex-reversed female (SRF) and normal male rainbow trout measured as ROS+ (percentage of spermatozoa exhibiting reactive oxygen species) production and TAC (total antioxidant capacity) in semen cryopreserved at different glucose concentration [optimal (0.15 M), low (0.11 M) and high (0.19 and 0.21 M for SRF and normal male rainbow trout, respectively)] in 7.5% methanol (glucose-methanol extender). Our hypothesis assumes that at non-optimal glucose concentrations, production of ROS+ is induced, resulting in damage to spermatozoa which should be characteristic for normal males and SRF rainbow trout. Such approach would allow to describe the characteristics of the response of spermatozoa of normal males and SRF to oxidative stress which is prerequisite for better understanding the mechanism of oxidative stress of normal males and SRF. This knowledge can be important for improvement of protocols of short-term storage and cryopreservation of SRF and normal males semen. We established baseline values for ROS+ and TAC for fresh semen from SRF and normal male rainbow trout and found a negative regression between those two characteristics in SRF. We determined the effect of glucose concentration on ROS+ production, TAC and sperm quality parameters of cryopreserved semen. TAC activity was monitored at the same time, and its relationship to oxidative stress was assessed. The glucose concentration significantly affected sperm motility, curvilinear velocity and viability after thawing. Cryopreservation resulted in increased ROS+ values in both tested groups. On the other hand, TAC values were significantly lower in cryopreserved samples than in equilibrated samples of SRF rainbow trout semen at all tested glucose concentrations. Our results strongly suggest that increasing the osmolality of the extender induces oxidative stress in spermatozoa of SRF and normal male rainbow trout. Most changes are related to freezing and thawing; however, some changes may occur during equilibration. Specific changes in oxidative stress characteristics occur in fresh and cryopreserved semen of SRF and normal males. An inverse relationship between ROS+ and TAC is likely caused by consumption of antioxidants by ROS+. Our results can be useful for optimization of cryopreservation protocols for salmonid fish. Further studies are necessary to elucidate the mechanisms that lead to differences in oxidative stress levels in semen from SRF and normal male rainbow trout.

Relationship between sperm telomere length and sperm quality in infertile men

Telomeres, noncoding and repetitive DNA sequences play a significant function in chromatin integrity. Telomere length is age-dependent in somatic cells, while it increases in sperm cell with age. Therefore, we aimed to assess sperm chromatin, leucocyte and sperm telomere length (LTL, STL) in spermatozoon of 38 infertile and 19 fertile men aged between 20 and 50years. Protamine deficiency (chromomycin A3 test), DNA fragmentation (TUNEL assay), lipid peroxidation (Bodipy probe) and telomere length (quantitative real-time PCR) were assessed. A significant decrease in mean of sperm concentration and motility and a significant increase in means of sperm abnormal morphology, DNA fragmentation, lipid peroxidation and protamine deficiency were observed in infertile compared with fertile men. In addition, the mean of LTL and STL were significantly shorter in infertile men compared with fertile individuals. We observed significant associations between telomere length with sperm concentration, DNA fragmentation and lipid peroxidation. We hypothesised that increased oxidative stress in spermatozoa of infertile men can result in abnormal packaging of chromatin, damage of DNA and shorter sperm telomere length. Together, these anomalies may account for fertility failure in these individuals.

Use of antioxidant could ameliorate the negative impact of etoposide on human sperm DNA during chemotherapy.

A previous study showed that N-acetylcysteine (NAC), used after in-vitro exposure to the gonadotoxic chemotherapeutic drug etoposide, has the ability to decrease DNA damage in human spermatozoa; however, it showed no benefit when used before exposure. This study aimed to evaluate the impact of the NAC on the preservation of sperm quality during in-vitro exposure to etoposide. Twenty semen samples were submitted to four experimental conditions: control, NAC-only incubation, etoposide-only incubation, and concomitant etoposide and NAC incubation. After in-vitro incubation, semen parameters, sperm chromatin condensation, sperm DNA fragmentation, sperm oxidative stress and sperm metabolism were used to evaluate the role of NAC in protecting human spermatozoa from etoposide. Etoposide did not affect semen parameters, nor did it cause sperm oxidative damage or alterations in glycolytic profile. However, it induced chromatin decondensation and DNA fragmentation, which were fully prevented by NAC. NAC was able to protect sperm DNA integrity during etoposide treatment in vitro, suggesting that NAC may be useful as an adjuvant agent in preserving male fertility during chemotherapy treatments.

Mechanisms of Sperm Oxidation: Breaking Down the Origins of Oxidative Activity.

Oxidative stress has been long considered an important cause of male infertility, and sperm-derived reactive oxygen species (ROS) have been considered one of the major sources. In article number 1900205, Issue 2, Netherton etal. have improved upon current technologies for detection of true ROS-derived oxidative events from those originated by mitochondrial compounds. Moreover, the authors have isolated proteins that bear lipid aldehyde adducts, in order to verify their origin. In their paper, Netherton et al. demonstrate that sperm-derived ROS do not contribute to sperm oxidative stress, which is an important finding, given that most studies consider altered sperm a major source of seminal ROS. Moreover, adducted proteins are mostly of prostatic origin, which leads to questions regarding how and where the oxidative events occur. Under the light of this study and the methodological improvements it has brought, it may be important to revisit some foundation studies in semen and sperm oxidative stress.

Does supplementation of vitamin C, reduced glutathione or their association in semen extender reduce oxidative stress in bovine frozen semen?

ABSTRACT The aim of this study was to evaluate the addition of vitamin C, reduced glutathione and the association thereof to the bovine semen cryopreservation extender. The ejaculate from nine bulls were divided into four fractions, each corresponding to a treatment, namely: control group-semen diluted with Tris-yolk extender; vitamin C group-semen diluted in Tris-yolk extender supplemented with vitamin C (2.5mmol/mL); glutathione group-semen diluted in Tris-yolk extender supplemented with reduced glutathione (2.5mmol/mL) and associated group-semen diluted in Tris-yolk extender supplemented with vitamin C (1.25mmol/mL) and reduced glutathione (1.25mmol/mL). Afterwards, the semen was packed into French straws and submitted to cryopreservation using automated equipment. After cryopreservation, the semen was thawed and evaluated considering sperm motility, morphology, plasma membrane, acrosome, mitochondrial potential and oxidative stress, as well as the thermo resistance test. Extender’s supplementation with the association of vitamin C and reduced glutathione showed benefic effects on sperm motility and preservation of plasma and acrosomal membranes during semen cryopreservation, being also the group that showed higher values of reactive oxygen species. Thus, the association of both antioxidants contributed to the preservation of sperm cells in every analyzed characteristic, suggesting its use on bovine semen cryopreservation.

382 Gene polymorphism of 5, 10-methylene tetrahydrofolate reductase is related to boar semen quality

Abstract 5, 10-methylene tetrahydrofolate reductase (MTHFR) is an important enzyme in folate and homocysteine metabolism, and plays an important role in regulating folate levels, DNA synthesis and methylation in cells. Defects in the MTHFR gene can lead to spermatogenesis disorders and male sterility. Polymorphic loci of MTHFR gene and semen quality of 1,490 boars were examined to explore their relationship. Results showed there were 13 polymorphic loci on MTHFR gene exon in boars with different semen quality, among which loci 1 and 2 were missense mutations. For Duroc boars, although there were synonymous mutations at loci 3–5 and 11, the mutation had no effect on semen quality (P &amp;gt; 0.05). In addition to loci 13, loci 1–12 of the MTHFR gene had mutations, but it had no effect on semen quality in Yorkshire boars (P &amp;gt; 0.05). Interestingly, for Landrace boars, double mutation of MTHFR gene at 1–2, 6–10, and 12 loci (CC → TT) led to decreased sperm motility and increased abnormal sperm rate (P &amp;lt; 0.05). Further analysis showed seminal plasma MDA and hydrogen peroxide levels were increased in Landrace boars with the mutation of MTHFR gene at loci 1–2, 6–10 and 12 (P &amp;lt; 0.05). In conclusion, double mutation of MTHFR gene at 1–2, 6–10, and 12 loci decreased semen quality and increased oxidative stress in sperm, and these mutant loci may be potential biomarkers for predicting the semen quality of Landrace boars.

284 Gene polymorphism of 5, 10-methylene tetrahydrofolate reductase is related to boar semen quality

Abstract 5, 10-methylene tetrahydrofolate reductase (MTHFR) is an important enzyme in folate and homocysteine metabolism, and plays an important role in regulating folate levels, DNA synthesis and methylation in cells. Defects in the MTHFR gene can lead to spermatogenesis disorders and male sterility. Polymorphic loci of MTHFR gene and semen quality of 1,490 boars were examined to explore their relationship. Results showed there were 13 polymorphic loci on MTHFR gene exon in boars with different semen quality, among which loci 1 and 2 were missense mutations. For Duroc boars, although there were synonymous mutations at loci 3–5 and 11, the mutation had no effect on semen quality (P &amp;gt; 0.05). In addition to loci 13, loci 1–12 of the MTHFR gene had mutations, but it had no effect on semen quality in Yorkshire boars (P &amp;gt; 0.05). Interestingly, for Landrace boars, double mutation of MTHFR gene at 1–2, 6–10, and 12 loci (CC → TT) led to decreased sperm motility and increased abnormal sperm rate (P &amp;lt; 0.05). Further analysis showed seminal plasma MDA and hydrogen peroxide levels were increased in Landrace boars with the mutation of MTHFR gene at loci 1–2, 6–10 and 12 (P &amp;lt; 0.05). In conclusion, double mutation of MTHFR gene at 1–2, 6–10, and 12 loci decreased semen quality and increased oxidative stress in sperm, and these mutant loci may be potential biomarkers for predicting the semen quality of Landrace boars.