Lipid peroxidation in human spermatozoa and maintenance of progressive sperm motility

Exploratory Metabolomics and Lipidomics Profiling Contributes to Understanding How Curcumin Improves Quality of Goat Semen Stored at 16 °C in Tropical Areas

Reactive oxygen species (ROS) exert a vital role in sperm quality during semen preservation, where excessive ROS leads to oxidative damage and undermines sperm integrity. Curcumin, a botanical extract, is capable of neutralizing ROS and enhancing the activity of antioxidant enzymes. This study was aimed at evaluating the effects of curcumin on sperm viability, acrosome integrity, and antioxidant levels, as well as metabolomic and lipidomic profiles. The results demonstrated that curcumin at 25 µmol/L significantly enhanced sperm motility, plasma membrane, and acrosome integrity, elevated the levels of antioxidant enzymes (T-AOC, CAT, SOD), and decreased ROS production (p < 0.05). Metabolomic analysis identified 93 distinct metabolites that showed significant differences between the control and curcumin-treated groups. KEGG pathways emphasized the participation of these metabolites in key metabolic processes such as the citric acid cycle, cholesterol metabolism, and fatty acid metabolism. Curcumin treatment brought about notable variations in lipid profiles, including increased levels of phosphatidylcholine, acylcarnitine, and triglyceride over the storage time, suggesting enhanced lipid anabolic activity. Overall, the supplementation of curcumin at 25 µmol/L effectively mitigates oxidative stress and prolongs the viability of semen storage at 16 °C by modulating specific metabolic and lipid profiles.

A systematic review and meta-analysis of the placebo effect on both semen quality and male infertility

INTRODUCTION

Placebo influence on such objective indicators, as sperm quality and infertility, has not been studied previously, but some studies report that placebo may distort even objective outcomes. The aim of current study is to assess the placebo effect on fertility in patients suffering from sperm abnormalities and/or infertility.

EVIDENCE ACQUISITION

We conducted a search of two databases (Scopus and MEDLINE) and identified placebo-controlled clinical trials which focused on sperm abnormalities and/or male infertility treatment. Primary outcomes included changes in semen parameters (volume, total count, sperm concentration in semen, progressive motility, morphology (normal cells)). Secondary outcomes included DNA fragmentation and change in pregnancy rate.

EVIDENCE SYNTHESIS

Seventy-seven articles published from 1983 to 2022 were included. Statistically significant changes were observed for the following values: total sperm count, mean change 0.16 (95% CI 0.05, 0.26); P=0.004, I2=75.1%; and progressive motility, mean change 0.13 (95% CI 0.02, 0.24); P=0.026, I2=84.9%. In contrast, placebo did not affect sperm concentration, sperm volume, sperm morphology or DNA fragmentation index. The publication bias for all the values measured with Egger's test and funnel plots was low.

CONCLUSIONS

The current meta-analysis indicated a statistically significant increase of total sperm count and progressive motility in the placebo group. In contrast, placebo did not affect sperm concentration, sperm volume, sperm morphology and DNA fragmentation index. These findings should be considered while planning or analyzing placebo-controlled clinical trials.

Mito-Tempo improves acrosome integrity of frozen-thawed epididymal spermatozoa in tomcats

Introduction

In tomcats, epididymal spermatozoa provide an additional source of male gametes available for cryopreservation. While this procedure is feasible, the survival rate and motility of epididymal cat spermatozoa are both low after thawing. Cryopreservation is known to induce oxidative stress in spermatozoa, with mitochondria and the plasma membrane being the two major generation sites, and an imbalanced presence of free radicals is a possible cause for this low survival rate. Different antioxidants have been tested before for their effect on cryopreserved cat spermatozoa quality, with varying results. Here, we used Mito-Tempo, which is a synthetic mitochondria-targeted antioxidant and a specific scavenger of the mitochondrial superoxide system. By supplementing Mito-Tempo with the freezing extender, we aimed to improve the sperm quality of frozen-thawed cat epididymal spermatozoa.

Methods

Epididymal spermatozoa obtained from twelve tomcats were assessed for motility and concentration. Prior to freezing, samples were diluted in TRIS buffered extender with egg yolk and glycerol and divided into five aliquots supplemented with 0 (control), 0.5, 5, 50, and 1005M of Mito-Tempo. After thawing, sperm motility, concentration, morphology, plasma membrane integrity, acrosome integrity, and mitochondrial membrane potential were evaluated. A Friedman rank sum test with a Bonferroni post-hoc test was used to determine statistical in-between group differences in post-thaw semen parameters.

Results and discussion

The results indicated a slight improvement in acrosome integrity across all groups that were supplemented with Mito-Tempo, with the group that received 55M of Mito-Tempo showing the greatest improvement [(median of 67.99%, IQR of 5.55) compared to the control group (median of 65.33%, IQR of 7.75; P = 0.05)]. For all other sperm parameters, no significant differences (P > 0.05) were detected between different Mito-Tempo concentrations. These findings highlight the protective effect of Mito-Tempo on acrosome integrity and suggest that 55M is the most effective concentration for maintaining acrosome integrity. Since Mito-Tempo has shown a positive effect on multiple sperm parameters in other species, such as men, boars, roosters, rams, and bulls, we need to conclude that species-specificity may play a role here.

Sperm Lipid Markers of Male Fertility in Mammals

Sperm plasma membrane lipids are essential for the function and integrity of mammalian spermatozoa. Various lipid types are involved in each key step within the fertilization process in their own yet coordinated way. The balance between lipid metabolism is tightly regulated to ensure physiological cellular processes, especially referring to crucial steps such as sperm motility, capacitation, acrosome reaction or fusion. At the same time, it has been shown that male reproductive function depends on the homeostasis of sperm lipids. Here, we review the effects of phospholipid, neutral lipid and glycolipid homeostasis on sperm fertilization function and male fertility in mammals.

Sperm DNA damage and seminal antioxidant activity in subfertile men

Supraphysiological ROS levels can lead to apoptosis, lipid peroxidation, and DNA and protein damage. This pilot study aimed to investigate the sperm oxidative damage in subfertile men, to describe the relationship between the antioxidant system and ROS. Sixty-four semen samples were categorised according to the evaluated routine parameters (WHO, WHO laboratory manual for the examination and processing of human semen, 2010). Results were cross-referenced with the DNA damage [Comet (n = 53) and TUNEL (n = 49) assays], antioxidant enzyme activity [SOD (n = 51), CAT (n = 48) and GST (n = 48)], and content of total thiols (n = 36), lipid hydroperoxides (n = 35) and MDA (n = 31). Compared to pathospermic samples, normozoospermic presented 40%-45% fewer spermatozoa with fragmented DNA, 19% fewer hydroperoxides, and slightly higher total thiols and MDA levels. Asthenozoospermic/asthenoteratozoospermic samples had the lowest GST activity. SOD and CAT showed a similar trend. Our results evidenced significant positive correlations between DNA damage and immotile spermatozoa; SOD and CAT, GST and total thiols; CAT and GST; total thiols and sperm concentration; and MDA levels and head/midpiece abnormalities and hydroperoxides. This work contributes to the existing body of knowledge by showing that the oxidative status correlates with the classic sperm analysis parameters. Oxidative stress and DNA damage evaluation might be a valuable diagnostic and prognostic tool in cases of idiopathic male subfertility.

Characterization of seminal parameters, sperm morphometry, micromorphology, and ultrastructure in gray brocket deer (Mazama gouazoubira, Fischer, 1814)

Populations of gray brocket deer (Mazama gouazoubira) are declining; yet, knowledge on the reproductive biology of this species remains limited. Therefore, this study aimed to describe morphology, viability, membrane integrity, mitochondrial activity, morphometry, micromorphology, and ultrastructure of the gray brocket deer sperm. Three adult male gray brocket deer were used in the study. Semen collection was performed using electroejaculation. Semen were analyzed by evaluating pH, motilities, vigor, mass movement, volume, concentration, viability, membrane integrity, mitochondrial activity, morphology, and morphometry. Micromorphology and ultrastructure of sperm were analyzed using scanning and transmission electron microscopy (SEM and TEM), respectively. There was no significant difference among males regarding on pH, motilities, vigor, mass movement, volume, concentration, viability. High values for membrane integrity, mitochondrial activity, and normal sperm were observed. The most frequent defects were simple bent tail and bowed midpiece. The head length, and width, midpiece, and tail length were 8.5, 4.4, 11.5, and 41.3 μm, respectively. SEM sperm showed paddle-shaped heads, with apical ridge and serrated band on the equatorial segment. TEM revealed the nucleus, acrosome, plasma membrane, mitochondria sheath, proximal centrioles, segmented columns, axoneme, outer dense fibers, and fibrous sheath. SEM and TEM showed the presence of some abnormalities. These results are expected to provide baseline values of diverse semen parameters, contributing toward the development of reproductive biotechnologies for gray brocket deer and, other deer species at risk of extinction.

Incubation of human sperm with micelles made from glycerophospholipid mixtures increases sperm motility and resistance to oxidative stress

Membrane integrity is essential in maintaining sperm viability, signaling, and motility, which are essential for fertilization. Sperm are highly susceptible to oxidative stress, as they are rich in sensitive polyunsaturated fatty acids (PUFA), and are unable to synthesize and repair many essential membrane constituents. Because of this, sperm cellular membranes are important targets of this process. Membrane Lipid Replacement (MLR) with glycerophospholipid mixtures (GPL) has been shown to ameliorate oxidative stress in cells, restore their cellular membranes, and prevent loss of function. Therefore, we tested the effects of MLR on sperm by tracking and monitoring GPL incorporation into their membrane systems and studying their effects on sperm motility and viability under different experimental conditions. Incubation of sperm with mixtures of exogenous, unoxidized GPL results in their incorporation into sperm membranes, as shown by the use of fluorescent dyes attached to GPL. The percent overall (total) sperm motility was increased from 52±2.5% to 68±1.34% after adding GPL to the incubation media, and overall sperm motility was recovered from 7±2% after H2O2 treatment to 58±2.5%)(n = 8, p<0.01) by the incorporation of GPL into sperm membranes. When sperm were exposed to H2O2, the mitochondrial inner membrane potential (MIMP), monitored using the MIMP tracker dye JC-1 in flow cytometry, diminished, whereas the addition of GPL prevented the decrease in MIMP. Confocal microscopy with Rhodamine-123 and JC-1 confirmed the mitochondrial localization of the dyes. We conclude that incubation of human sperm with glycerolphospholipids into the membranes of sperm improves sperm viability, motility, and resistance to oxidizing agents like H2O2. This suggests that human sperm might be useful to test innovative new treatments like MLR, since such treatments could improve fertility when it is adversely affected by increased oxidative stress.

Effect of ghrelin on total antioxidant capacity, lipid peroxidation, sperm parameters and fertility in mice against oxidative damage caused by cyclophosphamide

Cyclophosphamide is a drug used for chemotherapy and as an immune-suppressive in the organ transplantation. Despite its many clinical implications in the treatment of cancers, this drug has toxic effects on the reproductive system. This study aimed to evaluate the effect of ghrelin against the damages caused by cyclophosphamide. In this experimental study, 40 male mice were randomly divided into four groups: (i) control; (ii) cyclophosphamide; (iii) cyclophosphamide + ghrelin; and (iv) ghrelin. Cyclophosphamide (100 mg/kg body weight), once a week, and ghrelin (80 μg/kg body weight), daily, were administered intraperitoneally for 5 weeks. After 5 weeks, the epididymides were removed and the lipid peroxidation, total antioxidant capacity and sperm parameters were examined. The fertility rate was evaluated by performance in vitro fertilisation. In the mice exposed to cyclophosphamide, the number of spermatozoa and viability, as well as total antioxidant capacity, decreased significantly (p < .05). The increase in the abnormal sperm and MDA levels was observed (p < .05). In addition, the fertility rate decreased in this group, while the use of ghrelin significantly improved the above disorders in the treatment group (p < .05). The findings of this study showed that ghrelin attenuates negative effects caused by cyclophosphamide in the sperm parameters and enhances the fertility.

Enzymatic scavengers in the epididymal fluid: comparison between pony and miniature breed stallions

The use of stallion semen collected from cauda epididymis for AI has increased due to the new protocols available for cryopreservation. Preserving the genetic material from valuable males that suffer sudden death or other events that prematurely end the stallion's reproductive life is an important strategy for Stud breeding management. While protecting spermatozoa from oxidative stress and infectious agents, the epididymis promotes the enhancement of sperm cell morphology and changes in membrane protein profile, increasing its fertility potential. The epididymal fluid must be a balanced redox environment to allow sperm preservation and protein-protein and protein-lipids interactions to quantify. The aim of this study was quantify the enzymatic ROS scavengers in epididymal fluid of pony and miniature breed stallions. Epididymides from 8 pony stallions and 12 miniature breed stallions were dissected and fluid from caput, corpus and cauda epididymis collected. Spermatozoa were separated of epididymal fluid by 2-step centrifugation. The activities of catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were measured and compared between stallion groups and epididymal regions. The three enzymes were present in all epididymal regions tested, with higher activities of catalase and SOD in cauda epididymis in miniature breed stallions (P<0.05). GPx activity was higher in caput epididymis in pony stallions (P<0.05), however with no difference to fluid from cauda epididymis of both breeds. These results show a difference in antioxidant enzymatic scavengers between pony and miniature breed stallions. Also, our data confirm the protective role of cauda epididymis, preserving spermatozoa integrity from oxidative damage. As glutathione peroxidase is involved in several signaling pathways, its constant activity during epididymal transit corroborates the importance of this enzyme for spermatozoa maturation.

Association between sperm quality, oxidative stress, and seminal antioxidant activity

OBJECTIVES

To determine seminal antioxidant capacity, oxidative stress markers, and their association with semen quality as oxidative stress is considered to be a major etiological factor in male infertility.

SUBJECTS AND METHODS

Semen samples were obtained from 138 men and categorized on the basis of sperm count, motility, and morphology. Seminal oxidative and antioxidant markers are as follows: lipid peroxidation (LPO), protein carbonyls (PC), superoxide dismutase (SOD), catalase (CAT), thiols, and ascorbic acid were determined.

RESULTS

Sperm count significantly correlated positively with progressive sperm motility and normal morphology. Sperm count and normal morphology showed significant negative correlation with LPO and PC. Sperm count and progressive motility showed significant positive relationship with SOD. The SOD, CAT, and thiols positively whereas LPO and PC negatively associated with elevated sperm count.

CONCLUSION

Insufficient antioxidant enzymes and increased oxidative stress may attribute to the risk of declining semen quality and hence protective role for antioxidant enzymes against the oxidative damage cannot be ruled out.

Detection of lipid peroxidation reaction in frozen-thawed epididymal cat spermatozoa using BODIPY(581/591) C11

Lipid peroxidation is considered to be an important cause of sperm membrane damage, resulting in an apparent reduction of reproductive fecundity. Recently, a new lipophilic fluorescent dye probe (BODIPY(581/591) C11; Invitrogen Singapore Pte Ltd, Singapore) has been demonstrated to be a highly sensitive indicator for the physiological oxidation of cell membrane fatty acids. The objectives of this study were: (i) to detect lipid peroxidation in frozen-thawed epididymal cat spermatozoa using the BODIPY(581/591) C11 and (ii) to study the effect of semen extender in protecting sperm membrane from lipid peroxidation [100-mm ferrous ion, ferrous sulphate (FeSO(4))]. Epididymal cat spermatozoa were collected from eight male cats. Two straws of sperm sample from each cat were cryopreserved. After thawing, the semen extender from the first straw was removed and the sperm pellet was resuspended with Tris buffer (control). The semen sample from the other straw was equally divided: one sample contained semen extender (treatment A) and one contained no extender (treatment B); both were incubated with FeSO(4). Semen samples were labelled with the BODIPY(581/591) C11 probe and evaluated by flow cytometry at 0 and 6 h after thawing (control), 6 h after the addition of FeSO(4) (treatment A), and 30 min and 6 h after the addition of FeSO(4) (treatment B), respectively. The percentage of lipid peroxidation was higher after treatment B (51.3 +/- 23.9) and 6-h incubation compared with the control and treatment A (p < 0.05). Furthermore, the percentage of lipid peroxidation after treatment B increased during the incubation time (p < 0.05). In conclusion, the high percentage of lipid peroxidation after treatment B indicated that FeSO(4) induced membrane damage in cat spermatozoa, which could be detected by BODIPY(581/591) C11. This marker is suggested to be a beneficial tool for the evaluation of lipid peroxidation. Furthermore, the use of semen extender seemed to protect cat spermatozoa membranes from lipid peroxidation.

Activity of antioxidant enzymes in seminal plasma and their relationship with lipid peroxidation of spermatozoa

PURPOSE

To determine the activity of seminal plasma catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPX) and their relationship with malondialdehyde (MDA), as a marker of lipid peroxidation, content of spermatozoa and seminal plasma in normozoospermic and asthenozoospermic males.

MATERIALS AND METHODS

Semen samples were obtained from 15 normozoospermic and 30 asthenozoospermic men.

RESULTS

We observed inverse correlations between activities of CAT (k/mL) and SOD (U/mL) in seminal plasma with MDA content of spermatozoa from normozoospermic samples (r =- 0.43, p < 0.05 and r =- 0.5, p < 0.05, respectively). Significant correlations were observed between total activity CAT (k/total seminal plasma) with total SOD (U/total seminal plasma) and GPX activity (mU/total seminal plasma) in seminal plasma from normozoospermic samples (r = 0.67, p = 0.008 and r = 0.455, p = 0.047, respectively). Furthermore, we found positive correlations between total activities of CAT, SOD and GPX with total content of MDA in seminal plasma (nmoL/total seminal plasma) from normozoospermic samples (r = 0.67, p = 0.003; r = 0.73, p = 0.003; r = 0.74, p = 0.004, respectively). In asthenozoospermic samples, there were no significant correlations observed between activities of CAT (k/mL), SOD (U/mL) and GPX (mU/mL) of seminal plasma with MDA content of spermatozoa. However, we found significant correlations between total activities of CAT (k/total seminal plasma) and SOD (U/total seminal plasma) with total content of MDA in seminal plasma (r = 0.4, p = 0.018 and r = 0.34, p = 0.03, respectively).

CONCLUSION

These findings indicate a protective role for antioxidant enzymes of seminal plasma against lipid peroxidation of spermatozoa in normozoospermic samples.

Effect of leukocytospermia and processing by discontinuous density gradient on sperm nuclear DNA fragmentation and mitochondrial activity

PURPOSE

To assess the effect of leukocytospermia and semen processing on sperm DNA and mitochondria.

METHODS

Twenty-two patients with and 41 without leukocytospermia were included. Sperm DNA fragmentation was assessed by the Comet assay, and mitochondrial activity by a colorimetric method for active mitochondria. Semen was processed using Percoll, and motility, DNA fragmentation, and mitochondrial activity were analyzed pre- and post-processing.

RESULTS

No differences were observed in age, abstinence, volume, sperm morphology, progressive motility, concentration, and vitality (p>0.10). Variables were grouped according to time (pre- vs post-processing) and group (leukocytospermia vs non-leukocytospermia) because no interactions could be observed. Leukocytospermia was associated to increased DNA fragmentation, while semen processing led to a decrease in DNA fragmentation and to increased mitochondrial activity.

CONCLUSION

While semen processing selects sperm with higher rates of DNA integrity independent of the presence or absence of leukocytes in semen, samples without leukocytospermia present more sperm without DNA fragmentation. Semen processing also selects sperm with higher mitochondrial activity.

Cut-off value of reactive oxygen species for predicting semen quality and fertilization outcome

Though the role of reactive oxygen species (ROS) in male infertility is widely investigated worldwide, there is a lack of adequate information on the cut-off value of ROS beyond which ART outcome may be adversely affected. The objective of the present study is to establish an upper level of ROS in semen samples which can be considered as a potential marker of good semen quality. Semen ejaculates were randomly collected from 338 male partners of infertile couples. The upper critical limit (UCL) of ROS was calculated from the control chart of normozoospermic patients and found to be 0.75x10(6) counted photons per minute (cpm)/10 million cells. This was further validated by estimating ROS in 17 proven fertile men and 38 patients undergoing intra cytoplasmic sperm injection (ICSI). As expected, all abnormal semen samples exhibited higher ROS as compared to nomozoospermic and proven fertile samples. All semen samples from proven fertile volunteers were found to be <0.075x10(6) cpm/10 million cells. On the basis of the calculated UCL, ICSI patients were divided into two groups: Group I (<UCL) and Group II (>UCL). The semen parameters, fertilization rate and pregnancy outcome were found to be significantly affected in Group II. Significant difference in live birth-rates was observed between Group I (47.6%) and Group II (17.6%) while no live-birth was recorded for ROS level >0.1x10(6) cpm/10 million cells. It is concluded that the upper cut-off value of normal semen samples that correlates with good semen quality is, therefore, in the order of 0.075-0.1x10(6) cpm/10 million cells. In addition to the WHO [1999] semen analysis, this range is expected to assist andrologists and clinicians in predicting semen quality and fertilization outcome in patients with male factor infertility undergoing ICSI.

Alteration of sperm quality and hormone levels by polycyclic aromatic hydrocarbons on airborne particulate particles

The objective of this study was to assess whether polycyclic aromatic hydrocarbons (PAHs) affect male reproductive functions in vivo. Male reproductive parameters included testis weight, sperm counts and motility, circulating follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone. The average body weight, testis weight, and epididymis weight in the exposed group were not significantly lower than that in the control group (p < 0.01). The daily numbers of sperm in the PAH-exposed groups were significantly lower than those in the control group. The motility of sperm in the PAH-exposed groups was significantly less than those in the control group. Plasma LH concentrations increased at the end of the exposure period and continued to increase after post-cessation of exposure to PAHs. Testosterone decreased at the end of the exposure period and increased after post-cessation of exposure. However, the follicle-stimulation hormone level remained relatively stable during the study period. The present study showed that PAHs can compromise sperm functions and alter endocrine hormone levels.

Sperm nuclear DNA fragmentation and mitochondrial activity in men with varicocele

OBJECTIVE

To verify the impact of varicocele on semen quality and sperm function (DNA integrity and mitochondrial activity).

DESIGN

Prospective study.

SETTING

Patients in an academic research environment.

PATIENT(S)

Seventeen patients with a clinical diagnosed varicocele of grade II or III and 20 men without a varicocele.

MAIN OUTCOME MEASURE(S)

Rate of sperm DNA fragmentation as assessed by the Comet assay and categorized as classes I (no DNA fragmentation), II (little DNA fragmentation), III (meaningful DNA fragmentation), and IV (high DNA fragmentation). Rate of mitochondrial activity as assessed by the diaminobenzidine (DAB) assay and categorized as grades I (all mitochondria active), II (most mitochondria active), III (most mitochondria inactive), and IV (all mitochondria inactive).

RESULT(S)

No statistically significant differences were found between the study and control groups with respect to age, ejaculatory abstinence, and round cell count. Men with varicocele had significantly higher ejaculate volume, concentration of immotile sperm, and neutrophil count and lower mean percentage of sperm concentration, progressive motility, and morphology than men in the control group. The study group presented a lower percentage of sperm with little DNA fragmentation (class II) and a higher percentage of sperm with DNA fragmentation (class IV). In addition, the study group presented a greater percentage of sperm with inactive mitochondria (class III).

CONCLUSION(S)

Compared with men without varicocele, men with varicocele had a higher percentage of cells with DNA fragmentation and sperm with inactive mitochondria. Indeed, varicocele causes a decrease in motility, concentration, and morphology and an increase in volume and concentration of immotile sperm and neutrophils. The sperm functional evaluation (DNA fragmentation and mitochondrial activity) could be important factors in deciding treatment options for men with varicocele.

Bacteria trigger oxygen radical release and sperm lipid peroxidation in in vitro model of semen inflammation

OBJECTIVE

To assess the in vitro effect of five bacterial strains isolated from semen samples (Escherichia coli, Staphylococcus haemolyticus, Streptococcus oralis, Bacteroides ureolyticus, and Ureaplasma urealyticum) on reactive oxygen intermediate (ROI) release and lipid sperm membrane peroxidation in the coincubated suspensions of white blood cells (WBC) with spermatozoa.

DESIGN

An in vitro model of semen infection.

SETTING

Basic research laboratory.

PATIENT(S)

Healthy normozoospermic volunteers and healthy blood donors.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Chemiluminescent assay was used to evaluate ROI generation by WBC. Malondialdehyde (MDA) concentration was determined in sperm lysates using high-performance liquid chromatography.

RESULT(S)

Of the bacterial strains tested, B. ureolyticus, S. haemolyticus, and E. coli caused the greatest damage to sperm membrane lipids. An increase in MDA levels in sperm lysates was a natural consequence of bacteria-induced ROI generation. The WBC usually enhanced harmful activity of the infectious agent toward the cell membranes.

CONCLUSION(S)

The harmful effect of bacteria on spermatozoa depends on the type and species of microorganisms invading, colonizing, or infecting the male genital tract and is associated with the accompanying oxidative stress. The presence of leukocytes in semen appears to be the additional factor enhancing the sperm lipid membrane peroxidation, which may affect the fertility status.

Impact of cryopreservation and reactive oxygen species on DNA integrity, lipid peroxidation, and functional parameters in ram sperm

Assisted reproduction using frozen-thawed semen has practical advantages, although cryopreservation is detrimental to sperm fertility in most mammals. We examined the influence of cryopreservation and reactive oxygen species (ROS) on ram sperm DNA stability (using SCSA), lipid peroxidation (LPO), chlortetracycline fluorescence (CTC) patterns, motility and viability. In Experiment 1, DNA integrity, LPO, CTC, motility and viability tests were performed on fresh and cryopreserved sperm after 0, 6, and 24 hr in synthetic oviductal fluid (SOF). In Experiment 2, fresh sperm were incubated in serum-free SOF (SOF-S; 1, 4, and 24 hr) with 0, 50, 150, or 300 microM H2O2 then assayed. Cryopreservation increased the percentage of sperm with a high DNA fragmentation index (%DFI), decreased the percentages of motile and viable sperm at thawing (0 hr), but did not affect LPO. H2O2 (150 or 300 microM) increased %DFI after 24 hr. LPO or sperm viability were not affected by H2O2, although most motility parameters decreased. H2O2 decreased the percentage of chlortetracycline pattern F sperm at 4 hr and increased the percentage of acrosome-reacted sperm (pattern AR) after 1 hr. Pooled data of Experiment 2 showed LPO was positively correlated with SCSA (r = 0.29 to r = 0.59; P < 0.05 to P < 0.01), while most motility parameters and the percentage of viable sperm were negatively correlated with LPO (r = -0.30 to r = -0.38; P < 0.05 to P < 0.01). LPO was positively correlated with the percentage of pattern AR sperm (r = 0.33; P < 0.01). Cryopreservation and H2O2 promote DNA instability in ram sperm, though motility is a more sensitive indicator of oxidative stress than the other parameters investigated.

Malondialdehyde levels in sperm and seminal plasma of asthenozoospermic and its relationship with semen parameters

BACKGROUND

Toxic lipid peroxides are known to cause various impairments of sperm cells and may play a major role in the etiology of male infertility. We determined the level of lipid peroxidation as indicated by malondialdehyde (MDA) in the spermatozoa and seminal plasma of asthenozoospermic and normozoospermic males.

METHODS

MDA of spermatozoa and seminal plasma was determined in 35 asthenozoospermic and 15 normozoospermic men by spectrofluorometry. Semen analysis was done according to the WHO standard.

RESULTS

MDA concentration in the spermatozoa of asthenozoospermic was significantly higher than in normozoospermic males (0.14+/-0.059 and 0.09+/-0.04 nmol/10 x 10(6) spermatozoa respectively). The mean+/-S.D. MDA value in the seminal plasma of asthenozoospermic and normozoospermic were 1.35+/-0.42 and 1.2+/-0.3 nmol/ml seminal plasma respectively.

CONCLUSIONS

Lipid peroxidation has a deleterious effect on the semen quality and MDA is an index of lipid peroxidation which may be a diagnostic tool for the analysis of infertility in the asthenozoospermic patients.

Detection of lead-induced oxidative stress in the rat epididymis by chemiluminescence

It has been shown that lead (Pb) is able to induce lipid peroxidation, one of the main manifestations of oxidative stress. In this study we examined the relationship between chronic Pb exposure and level of reactive oxygen species (ROS) in reproductive system tissues of sexually mature male Wistar rats. One group of animals (control, K) was allowed to drink distilled water, the second group (Pb) was allowed to drink freely 1% aqueous solution of lead acetate. Another groups had a following supplements: rats were allowed to drink distilled water containing vitamin C (vit C) at concentration of 500 mg/l or Trolox (a vitamin E analog) at concentration of 48 mg/l or vit C (500 mg/l) + Trolox (48 mg/l). The similar groups among Pb-treated animals were examined after treatment with the same vitamins and using the same vitamin doses, dissolved in 1% aqueous solution of lead acetate. In all cases the time of drinking was 6 months. It was found that lead content in samples of tissues from testis, epididymis and in a whole blood in Pb- and Pb with antioxidants treated rats was significantly elevated. Chemiluminescence (CL) emitted by the Pb-treated tissues was significantly higher when compared to the light emission by tissues isolated from the animals of control group. The increase in the CL caused by lead occurs in the following increasing order within the studied tissues: cauda of epididymis < testis < caput of epididymis (19%, 39% and 51%, respectively). Dietary vit C supplementation to the Pb-treated rats for 6 months period decreased the CL from caput of epididymis, cauda of epididymis and testis (by 43%, 24%, 39%, respectively) more effectively in comparison to the control group (35%, 17%, 33%, respectively). Also stronger quenching effect on the light emission from the above mentioned tissues after Trolox supplementation was observed in the Pb-treated group (42%, 21%, 35%, respectively) than in the control group (23%, 13%, 13% respectively). The combination of both antioxidants treatments (vit C and Trolox) did not give a higher significant quenching effect compared to the treatment with the vitamins separately. No ultrastructural changes were found in the seminiferous epithelium of Pb-treated animals. However, we found abnormalities in ultrastructure of epididymal epithelial cells and epididymal spermatozoa in rats of Pb-treated groups. These findings provide ex vivo evidence that Pb causes oxidative cellular damage in reproductive system tissues of adult male rats, which may be closely associated with the ROS production.

Analysis of lipid peroxidative levels in seminal plasma of infertile men by high-performance liquid chromatography

For the purpose to evaluate the significance of lipid peroxidative products on male infertility, the levels of malondialdehyde (MDA), which is one of the final products of lipid peroxidation in seminal plasma, were determined. Ninety-three male infertile patients were divided into obstructive azoospermic group (12 cases), non-obstructive azoospermic group (15 cases), oligozoospermic group (21 cases), asthenozoospermic group (19 cases), oligoasthenozoospermic group (16 cases) and oligoasthenoteratozoospermic group (10 cases). Eighteen fertile males were included in the control group. MDA concentrations of seminal plasma in the fertile and infertile men were detected by high-performance liquid chromatography (HPLC). The results showed that the concentration of MDA in seminal plasma differed significantly between the control group and all the infertile groups (P < 0.01) except the obstructive azoospermic group, between the oligoasthenozoospermic group and the oligozoospermic and asthenozoospermic groups (P < 0.01), and between the oligoasthenoteratozoospermic group and the oligozoospermic and asthenozoospermic groups (P < 0.01). MDA concentration of seminal plasma in the oligoasthenoteratozoospermic group differed significantly from that in the oligoasthenozoospermic group (P <0.05). The results suggested that detection of MDA concentrations in seminal plasma by HPLC has an indicative value on the diagnosis of male infertility induced by overproduction of reactive oxygen species in male reproductive system.

High-performance liquid chromatographic detection of lipid peroxidation in human seminal plasma and its application to male infertility

BACKGROUND

A simple and reliable high-performance liquid chromatographic (HPLC) method has been developed and validated for the analysis of malondialdehyde (MDA) in human seminal plasma.

METHODS

After human seminal plasma is hydrolyzed, MDA is reacted with thiobarbituric acid (TBA) to form MDA(TBA)(2), a red-colored adduct with maximum absorbance at 532 nm. HPLC separation of the adduct in human seminal plasma was performed on a Lichrospher C(18) column.

RESULTS

A mobile phase composed of 0.025 mol/l KH(2)PO(4) (pH 6.2)--methanol in the ratio 58:42 (v/v) was found to be the most suitable for this separation. Under the chromatographic conditions described, the MDA-TBA adduct had a retention time of approximately 4 min and good separation and detectability of MDA in human seminal plasma sample was obtained. The method proved to be linear calibration in the range of MDA from 0.10 to 2.50 micromol/l. The relative standard deviations of within- and between-assay for MDA analysis were 3.1% and 3.8%, respectively. The average recovery was 90.0-98.8% for the human seminal plasma samples. The method has been successfully applied to the study of the lipid peroxidation levels in the seminal plasma of male infertility. Semen samples were obtained from healthy volunteers and infertile males. Ejaculates were classified into studied subgroups and defined as: obstructive azoospermia, non-obstructive azoospermia, oligozoospermia, asthenozoospermia, oligoasthenozoospermia and oligoasthenoteratozoospermia. With the exception of obstructive azoospermic group, MDA concentrations of seminal plasma in control group had very significant difference with those in other infertile groups (P < 0.01).

CONCLUSIONS

This indicated that lipid peroxidation could be harmful to male sperm and reproductive system, which may lead to male infertility.

Oxidative stress and male reproductive biology

Spermatozoa were the first cell type in which the cellular generation of reactive oxygen was demonstrated. This activity has now been confirmed in spermatozoa from all mammalian species examined including the rat, mouse, rabbit, horse, bull and human being. Under physiological circumstances, cellular redox activity is thought to drive the cAMP-mediated, tyrosine phosphorylation events associated with sperm capacitation. In addition to this biological role, human spermatozoa also appear to suffer from oxidative stress, with impacts on the normality of their function and the integrity of their nuclear and mitochondrial DNA. Recent studies have helped to clarify the molecular basis for the intense redox activity observed in defective human spermatozoa, the nature of the subcellular structures responsible for this activity and possible mechanisms by which oxidative stress impacts on these cells. Given the importance of oxidative damage in the male germ line to the origins of male infertility, early pregnancy loss and childhood disease, this area of sperm biochemistry deserves attention from all those interested in improved methods for the diagnosis, management and prevention of male-mediated reproductive failure.

Values of sperm thiobarbituric acid-reactive substance in fertile men

BACKGROUND

The objective of this study was to establish for the first time reference levels of sperm malondialdehyde, a stable lipid peroxidation product, in a cohort of fertile men.

METHODS

Sperm malondialdehyde, a thiobarbituric acid-reactive substance, was assayed using the 2-thiobarbituric acid method.

RESULTS

Sperm malondialdehyde levels, expressed in nM/10(8) spermatozoa, were normally distributed in our cohort of fertile men and averaged 0.0287 +/- 0.0162 (mean +/- S.D.).

CONCLUSIONS

Given the impact of lipid peroxidation on spermatozoa and thereby on male fertility, the assay of sperm membrane thiobarbituric acid-reactive substance is clearly of interest. Malondialdehyde levels found in our study form a basis for normal values of sperm thiobarbituric acid-reactive substance observed in the semen of fertile men.

Cryopreservation of fractionated, highly motile human spermatozoa: effect on membrane phosphatidylserine externalization and lipid peroxidation

INTRODUCTION

This study investigated lipid peroxidation (LPO) and membrane integrity following cryopreservation-thawing.

METHODS

Infertile men (study group) and donors (control group) were examined. Purified populations of highly motile spermatozoa were cryopreserved using TEST-yolk buffer and glycerol (TYB-G) followed by quick thaw. LPO was measured by a spectrophotometric assay, with and without a ferrous ion promoter. Annexin V binding was used to assess membrane translocation of phosphatidylserine (PS).

RESULTS

Pre-freeze LPO was significantly higher in the study than in the control group (P = 0.03). In both groups, LPO measurements after thawing were significantly higher than the pre-freeze samples not exposed to TYB-G (P = 0.002 and P = 0.001 respectively). However, when the pre-freeze samples with TYB-G were compared with the post-thaw samples (all exposed to TYB-G), these differences were not significant. There was a significant increase in PS externalization following cryopreservation in both groups (P = 0.02 and P = 0.003 respectively). In donors, pre-freeze LPO concentrations had a significant positive correlation with thawed spermatozoa depicting PS externalization (r = 0.77, P = 0.04).

CONCLUSION

Although patients had higher basal LPO than donors, LPO did not differ between fresh and cryopreserved-thawed fractionated motile spermatozoa. Freezing-thawing was associated with translocation of PS to the external membrane leaflet.