Effect of reactive oxygen species and the activity of antioxidant systems on human semen; association with male infertility

A range of compounds with a role in oxidative stress were measured in ejaculates from 40 normozoospermic individuals and 93 infertile males. Ejaculates were classified according to WHO criteria. Seminal plasma and the sperm cell fraction were assessed separately for superoxide dismutase (SOD), catalase, xanthine oxidase, capability for singlet oxygen trapping and content of thiobarbituric acid-reactive substances (TBARS). Pathological cases defined as oligozoospermia, asthenozoospermia, or teratozoospermia revealed different backgrounds of oxidative stress as reflected by different levels of tested substances in every type of sperm pathology. In the majority of abnormal ejaculates, a significant increase in intracellular activity of SOD, decreased intracellular levels of catalase, elevated levels of xanthine oxidase and TBARS, and severely impaired singlet oxygen trapping were observed when compared to normozoospermic ejaculates. Interrelationships between SOD and TBARS, and between xanthine oxidase and catalase, appeared to be of key importance when analysed separately in seminal plasma and in spermatozoa or in a combination of both. Elevated xanthine oxidase levels and low capacity for singlet oxygen trapping are statistically significant factors for the evaluation of male infertility which can develop as a result of persistent oxidative stress.     

Effect of reactive oxygen species in semen on the pregnancy of infertile couples

Objective:   We intended retrospectively to investigate whether reactive oxygen species (ROS) levels, detected in whole semen, were correlated with the actual pregnancy rate.
Methods:   A total of 89 patients with data of ROS in semen, attending our male infertility clinics from April 1994 to June 2000, were evaluated. Semen parameters were determined with computer assisted semen analyzer (CASA) and ROS production levels were measured using a computer-driven LKB Wallac 1251 Luminometer after the addition of 40 µL of 4 mM luminol at the patients' first visits. All of the participants were inquired about their partners' pregnancies after the mean follow-up of 24.0 months (range 1.4 to 74.1). They were divided into two groups (pregnant group: n  = 41, non-pregnant group: n  = 48) and their characteristics, semen profiles and integrated ROS levels were analyzed.
Results:   There was no difference between the pregnancy rate of ROS detectable cases and negative cases. However, the mean integrated ROS level in detectable cases of the non-pregnant group was significantly higher than that in detectable cases of the pregnant group (115.61 ± 74.32 mV/30 min/10⁶ sperm versus 7.22 ± 4.69 mV/30 min/10⁶ sperm, P  = 0.0033). Then, by calculating the receiver operating characteristics curve with 95% confidence intervals, 4.35 mV/30 min/10⁶ sperm was considered as a cut-off value of ROS in semen for pregnancy.
Conclusion:   These results indicate that (i) highly detectable ROS in whole semen of infertile patients may have implications in their partners' pregnancies and that (ii) detection of ROS in whole semen has a prognostic value for idiopathic male infertility.     

Scavenging effect of N-acetyl-L-cysteine against reactive oxygen species in human semen: a possible therapeutic modality for male factor infertility?

Summary. A new approach to reduce the level of reactive oxygen species (ROS) in human semen by using N-acetyl-L-cysteine (NAG) was evaluated. Semen samples were incubated with or without NAC (1.0 nig ml⁻¹) at room temperature. The chemiluminescent signal of the oxidation of luminol was detected by means of an MTP reader after 0, 20, 40, 60 and 120 min, respectively, using 200 μM luminol. In addition, the dose-dependent action of NAC (0.1, 1.0 and 5.0 mg ml⁻¹) and the influence of NAC on functional sperm parameters (motility and acrosome reaction) were studied.
ROS levels decreased significantly after 20 min incubation with NAG. This reduction was greater in the high ROS group (>30 000 counts/10⁷ viable sperm at t = 0) than in the low ROS group (<30 000). In addition, a marked dose-dependence of NAC was observed. Concerning sperm function, total sperm motility improved after incubation with NAC, but no significant change was observed with respect to the acrosome reaction.
NAC (at concentrations of 1.0 mg ml⁻¹) significantly reduced ROS in human semen and showed the possibility of improving impaired sperm function. After further testing NAC might be useful for the treatment of male infertility patients.     

Infection and reactive oxygen species

Summary. In previous years the physiologic and pathophysiologic significance of reactive oxygen species (ROS) on sperm function has been recognized. The impact of ROS during the invasion, adhesion and multiplication of microorganisms in the male genital tract are largely unknown. However, it is known that the resulting activation of leukocytes leads to an increased generation of ROS. There is growing evidence that spermatozoa are protected from detrimental ROS effects by the powerful antioxidants in seminal plasma since disturbances of sperm function by ROS were demonstrated in the absence of seminal plasma, i.e., during epididymitis or after semen preparation. If seminal plasma is present, ROS generated by physiologic numbers of granulocytes (< 1 times 10⁶ ml⁻¹) apparently do not damage spermatozoa. Interestingly, ROS generated by leukocytes during male genital tract infections are critical for the techniques of semen preparation for assisted reproduction. These ROS impair sperm function if the protective effects of seminal plasma are not present. The relevance of ROS production by higher leukocyte numbers in human semen is presently unknown as is the relevance of ROS generated in the female reproductive tract.
In previous years the ambiguous role of reactive oxygen species (ROS) generation in human semen has been recognized. On one hand, ROS appear to be involved in physiologic reactions such as capacitation (De Lamirande & Gagnon, 1995; Griveau et al. , 1995a), while on the other hand, there is ample evidence that an increased ROS production impairs sperm functions and the fertilizing capacity of spermatozoa (Ochsendorf & Fuchs, 1993; Aitken, 1994; Griveau et al. , 1995b). The objective of this review is to summarize the relevance of reactive oxygen species during infections of the male genital tract.     

Varicocelectomy reduces reactive oxygen species levels and increases antioxidant activity of seminal plasma from infertile men with varicocele

Several theories have been advanced to explain the mechanisms by which varicocele impairs male fertility. These theories include scrotal hyperthermia, retrograde flow of adrenal or renal metabolites, Leydig cell dysfunction and hypoxia. Varicocele is reported to be associated with elevated reactive oxygen species (ROS) production in spermatozoa and diminished seminal plasma antioxidant activity. The aim of this study was to investigate whether surgical correction of varicocele might reduce ROS or increase the antioxidant capacity of seminal plasma from infertile patients with varicocele. The study group consisted of 68 infertile males, selected from patients scheduled for varicocelectomy at Cairo University Hospital during the year 1999. Seminal plasma levels of two ROS [malondialdehyde (MDA), hydrogen peroxide (H2O2)] and one ROS radical [nitric oxide (NO)] were estimated as well as six antioxidants [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), vitamin C (Vit C), vitamin E (Vit E), albumin) on the day prior to varicocelectomy. For comparison, the same parameters were measured again 3 and 6 months post-operatively. A statistically significant reduction in the 3 month post-operative levels of MDA, H2O2 and NO was observed when compared with the pre-operative values. A further significant reduction took place during the following 3 months. Four of the six antioxidants tested (SOD, CAT, GPx, and Vit C) showed a significant increase in seminal levels when comparing 3-month post-operative with pre-operative values. A further significant increase of the four antioxidant levels took place during the following 3 months. No significant change in the level of seminal plasma albumen took place during the first 3 months after varicocelectomy, however, a significant increase was noted during the next 3 months. In contrast to other antioxidants, seminal plasma levels of Vit E showed a significant decrease when comparing 3-month post-operative with pre-operative values. A further significant decrease took place during the following 3 months. It is concluded that varicocelectomy reduces ROS levels and increases antioxidant activity of seminal plasma from infertile men with varicocele.     

Proteomic analysis of sperm proteins in infertile men with high levels of reactive oxygen species

Oxidative stress is a significant risk factor for male infertility. A pro‐oxidant testicular environment may alter the expression profile of functional sperm proteins and result in poor sperm quality. Patients and donors were divided into ROS (‐) and ROS (+) groups. Using computational studies, and data mining of available literature on spermatozoa, oxidative stress and proteomics, we identified three core regulatory proteins angiotensin‐converting enzyme (ACE), heat‐shock protein (Hsp70) family A member 2 (HSPA2) and ribosomal protein subunit 27A (RPS27A) and seven interlink proteins NOS2, SUMO2, UBL4A, FBXO25, MAP3K3, APP and UBC. HSPA2 was validated by Western Blot, while the localisation of ACE, RPS27A, MAP3K3 and APP was identified by immunocytochemistry. The obtained results showed that HSPA2 was 1.2 (ROS+) and 2.1 (ROS?) fold downregulated in spermatozoa from patients with high levels of reactive oxygen species (ROS). ACE and APP were localised in the post‐acrosomal region of spermatozoa, whereas RPS27A and MAP3K3 were localised either in the tail or sperm neck area. Our data show that these proteins may play a role in ROS‐induced male infertility.     

Generation of reactive oxygen species in subgroups of infertile men

The capacity to generate reactive oxygen species (ROS), both basally and after stimulation with the calcium ionophore A23187, was examined in the motile fraction of sperm isolated after swim-up from the semen of 10 naturally fertile men and three groups of infertile patients. The latter included: (1) men with a non-bacterial inflammation of the genital tract (n = 10); (2) men unable to impregnate their partners during an intra-uterine insemination programme (IUI) (n = 8) and their matched controls (n = 6); and (3) men with hypogonadotrophic hypogonadism (HH) who remained infertile after induction of spermatogenesis with gonadotrophin or gonadotrophin-releasing hormone therapy (n = 3) and their matched controls (n = 3). The levels of ROS production were elevated in the sperm of some infertile men with inflammation of the genital tract compared to those found in 10 naturally fertile men. In addition, sperm from those patients who remained infertile after an IUI programme produced higher amounts of ROS compared to their control group who became fertile. Similarly, the production of ROS by sperm from three patients with HH who remained infertile was significantly higher than those of the three men who became fertile. These data suggest that an excessive production of ROS by sperm may explain some cases of idiopathic male infertility.     

血小板内源性活性氧对血小板高敏性的调控机制

血小板高敏性对疾病的重要性越来越被学者们重视.本文着重讨论了血小板内源性活性氧对血小板高敏性的调控机制,以及该研究对相关药物的作用靶点、相关疾病的易感性及病因防治的参考作用.     

Clinical significance of reactive oxygen species in semen of infertile Indian men

Reactive oxygen species (ROS) levels in semen are believed to play both physiological and pathological roles in male fertility. The study was aimed to find the clinical significance of ROS levels in infertile Indian men. This pilot study included 33 idiopathic infertile men and 18 proven fertile controls. ROS levels in the washed sperm were measured using chemiluminescence assay and expressed as 10⁶ cpm per 20 million spermatozoa. Sperm count, percent sperm motility, and percent normal sperm morphology were found to be significantly ( P  < 0.0001) reduced in infertile men compared with the controls. Median (minimum, maximum range) ROS levels of the infertile group [24.90 (6.89, 44.71)] were found to be significantly ( P  < 0.0001) elevated compared with the fertile controls [0.167(0.15, 2.78)]. No significant correlation was seen between ROS levels and semen parameters. Elevated ROS levels in the idiopathic Indian infertile men may be one of the underlying reasons for impaired fertility. Therefore measurement of seminal ROS levels may be used in Indian infertile men for better understanding of the aetiology and selection of antioxidant regimen in the treatment of male infertility. However, large studies may be urgently warranted to find out the role of antioxidants in ROS elevated Indian infertile men through randomised, controlled clinical study.     

精子凋亡率与精子密度、活率、活力及活性氧关系探讨

目的 探讨精子凋亡率与精子密度、活率、活力与精浆活性氧关系.方法 分析85例男性不育患者精液样本,采用计算机辅助精液分析进行精液参数检测,采用Annexin V/PI染色法检测精子凋亡率,采用TBA法测定精浆活性氧.结果 精子凋亡率与精子密度之间有显著负相关性(P＜0.01);与精子活率之间无显著相关性(P＞0.05):与精子活力之间有显著负相关性(P＜0.05);与精浆活性氧之间有显著正相关性(P＜0.05).结论 精子捌亡率与精子密度和活力有相关性,精子凋亡率增加可能是少、弱精子症患者不育的原因之一,精浆活性氧升高可能是精子凋亡率增加的原因之一.     

The role of infections and leukocytes in male infertility

Declining birth rates are one of the problems facing society today. Male counterparts are responsible for about half of the infertility cases, and genitourinary tract infections may play a contributing role in approximately 15% of male infertility cases. Leukocytospermia is an established indicator of infection in the male urogenital tract, although other microorganisms such as bacteria and virus may also be contributors to the etiology of male infertility. The pathophysiology of these infectious agents may be initiated by a local inflammatory reaction resulting in an increase in reactive oxygen species (ROS). This results in testicular injury, thereby affecting sperm morphology, sperm motility, sperm viability and elevation of the seminal leukocyte as a result of the genital tract infection. The infectious and inflammatory changes can result in male infertility. It is proposed that high concentrations of seminal leukocyte and infectious agents may affect sperm function resulting in clumping of motile spermatozoa, decreasing acrosomal functionality and also causing alterations in sperm morphology. However, the literature has poorly clarified the role of infection in male infertility, provoking further debate and research on this topic.     

皮肤光老化、活性氧簇与抗氧化剂

皮肤长期反复暴露于日光紫外线（UV）下可导致皮肤光老化.近年来研究表明活性氧簇（ROS）在UV致皮肤光老化过程中起重要作用.UV可在皮肤中诱生高浓度ROS,这些具有一个或多个未配对电子的原子或分子如不能被皮肤抗氧化系统及时清除则会和皮肤中的核酸、脂质、蛋白质等生物大分子发生化学反应,并影响相关细胞信号转导途径和基因表达,导致皮肤光老化发生,使用抗氧化剂清除ROS可能成为一种重要的光老化防治策略.     

The role of testicular biopsy in the modern management of male infertility.

PURPOSE: We evaluate the traditional role of isolated testicular biopsy as a diagnostic tool, as opposed to the value as a therapeutic procedure for azoospermic men. MATERIALS AND METHODS: The medical records of azoospermic patients who were evaluated, and treated between 1995 and 2000 were retrospectively analyzed for history, physical examination findings, endocrine profiles, testicular histology and sperm retrieval rates. Based on these parameters, cases were placed into diagnostic categories that included obstructive or nonobstructive azoospermia. Diagnostic parameters used to distinguish obstructive from nonobstructive azoospermia were subjected to statistical analysis with the t-test, analysis of variance and receiver operating characteristics curve. RESULTS: A total of 153 azoospermic men were included in our analysis. Of men with obstructive azoospermia 96% had follicle-stimulating hormone (FSH) 7.6 mIU/ml. or less, or testicular long axis greater than 4.6 cm. Conversely, 89% of men with nonobstructive azoospermia had FSH greater than 7.6 mIU/ml., or testicular long axis 4.6 cm. or less. Receiver operating characteristics analysis revealed that FSH, testicular long axis, and luteinizing hormone were the best individual diagnostic predictors, with areas 0.87, 0.83 and 0.79, respectively. CONCLUSIONS: In the vast majority of patients obstructive azoospermia may be distinguished clinically from nonobstructive azoospermia with a thorough analysis of diagnostic parameters. Based on this result, we believe that the isolated diagnostic testicular biopsy is rarely if ever indicated. Men with FSH 7.6 mIU/ml. or greater, or testicular long axis 4.6 cm. or less may be considered to have nonobstructive azoospermia and counseled accordingly. These men are best treated with therapeutic testicular biopsy and sperm extraction, with processing and cryopreservation for usage in in vitro fertilization and intracytoplasmic sperm injection if they accept advanced reproductive treatment. Diagnostic biopsy is of no other value in this group. Men with FSH 7.6 mIU/ml. or less, or testicular long axis greater than 4.6 cm. may elect to undergo reconstructive surgery with or without testicular biopsy and sperm extraction, or testicular biopsy and sperm extraction alone depending on their reproductive goals.     

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

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

The role of reactive oxygen species in testicular dysfunction associated with varicocele

OBJECTIVE: To determine the level of malondialdehyde (MDA), an indirect indicator of lipid peroxidation-induced injury by reactive oxygen species, in testicular biopsy specimens from infertile patients with and without varicocele. PATIENTS AND METHODS: Levels of MDA were measured in the testicular biopsy specimens from 25 infertile men (15 with varicocele, mean age 30.0 years, SD 5.7, range 23-45, and 10 without, mean age 28.7 years, SD 4.2, range 21-34). All patients were evaluated by a detailed history, physical examination, semen analysis (at least twice), serum follicle-stimulating hormone and free testosterone levels, testicular biopsy and contact imprint. Scrotal colour Doppler ultrasonography was used to confirm suspected varicocele. The level of MDA in testicular biopsy specimens was measured using the thiobarbituric acid test and the results expressed per unit tissue weight. RESULTS: As a causal factor for infertility, varicocele was identified in 15 men (60%), testicular failure in four (16%), idiopathic infertility in four (16%) and obstruction in two (8%). Of the 15 patients with varicocele, eight had bilateral varicocele and it was subclinical in three; the varicocele was grade I in four, grade II in six and grade III in two. The mean (SD) MDA level in the men with a subclinical varicocele was 15.7 (3.1) pmol/mg tissue, while in those with grade I-III varicocele it was 32.9 (12.25), 37.1 (12.25) and 86.9 (2.89) pmol/mg tissue, respectively. The levels in patients with grade III varicocele were significantly greater than in the other groups (P < 0.05). The mean MDA level in patients with or without varicocele was 38.3 (22.92) and 33.5 (18.93) pmol/mg tissue, respectively (P > 0.05). CONCLUSION: These results suggest that increasing levels of MDA are associated with higher grades of varicocele and support a possible rationale for controlled trials in infertile men with varicocele.     

活性氧簇调控破骨细胞分化的研究进展

破骨细胞是影响骨重塑的关键细胞,其分化过程受包括活性氧簇(reactive oxygen species, ROS)在内的多种因子调控。ROS是氧气转化为水的过程中氧化还原反应的中间产物,可通过激活RANKL/RANK信号通路下游的NF-κB、MAPK和AKT等多条信号通路来促进破骨细胞分化。近年来,众多新型抗氧化剂显现出对破骨细胞分化成熟的靶向抑制作用,有望为骨质疏松症等溶骨亢进型疾病提供治疗新思路。本文对破骨细胞中ROS的产生与清除、ROS对于破骨细胞分化的调控作用和抗氧化剂治疗溶骨性疾病的研究进展进行综述,探讨ROS作为溶骨性疾病治疗靶点的巨大潜力。     

Reactive oxygen species and human spermatozoa: physiology and pathology

The role of reactive oxygen species (ROS) in the pathophysiology of human sperm function has been emphasized in recent years. ROS production in semen has been associated with loss of sperm motility, decreased capacity for sperm–oocyte fusion and loss of fertility. There is a current presumption that the most prolific source of ROS in sperm suspensions is an NADPH oxidase located in leukocytes or in spermatozoa which produces superoxide which is further converted to peroxide by the action of superoxide dismutase. Hydrogen peroxide has been recognized as the most toxic oxidizing species for human spermatozoa, which are very sensitive to lipid peroxidation owing to the high content of polyunsaturated fatty acids in their plasma membrane, though this is not the sole mechanism by which sperm function might be impaired by ROS. Although the excessive production of ROS is detrimental to human spermatozoa, there is a growing body of evidence which suggests that ROS are also involved in the physiological control of some sperm functions. This review focuses on the nature and source of the ROS generated by human spermataozoa as well as their operational mechanisms and their effects, which may be detrimental or beneficial.     

Effect of rotation on the generation of reactive oxygen species in human semen

Summary. Rotation of semen after liquefaction is a standard procedure in an Andrology laboratory. During rotation under aerobic conditions the semen is exposed to oxygen. Oxygen toxicity induces lipid peroxidation which is responsible for the loss of sperm function. The generation of reactive oxygen species was significantly increased after rotation. This may have a detrimental effect on sperm function during assisted reproduction.     

Association of ureaplasma urealyticum with abnormal reactive oxygen species levels and absence of leukocytospermia

PURPOSE: Ureaplasma urealyticum is a commensal of the lower genitourinary tract of many sexually active adults. The organism is more common in partners of infertile than fertile marriages. We conducted a prospective study at our tertiary care center to confirm a possible association between U. urealyticum and abnormal sperm function parameters. MATERIALS AND METHODS: A total of 50 consecutive male patients seeking general urology consultation for lower urinary tract symptoms characteristic of chronic prostatitis were evaluated. Urine and semen localization cultures were performed with additional semen cultures for U. urealyticum, Chlamydia trachomatis and Mycoplasma hominis. Specimens from 21 healthy men were used as controls. Specimens were analyzed by a computer assisted semen analyzer, and verified manually for concentration, percent motility and morphology. Leukocytospermia was measured by the Endtz test. Semen specimens were also analyzed for reactive oxygen species (ROS), acrosome reaction and mannose binding assay. RESULTS: Of the patients 17 had positive U. urealyticum cultures and the other cultures were negative. Patients with U. urealyticum had significantly higher ROS levels (log [ROS + 1] = 2.52 +/- 0.25) than those without U. urealyticum (1.49 +/- 0.20, p = 0.002) or controls (1.31 +/- 0.19, p = 0.002). Leukocytospermia was detected in only 1 of the 17 (6%) positive specimens and 4 (12%) negative specimens. CONCLUSIONS: Seminal ROS levels are elevated among patients with U. urealyticum. ROS induces lipid peroxidation, which reduces membrane fluidity and sperm fertilization capability, and may be the mechanism by which U. urealyticum impairs sperm function. Absence of leukocytospermia does not exclude U. urealyticum.