Seminal plasma metabolomics profiles following long (4-7 days) and short (2 h) sexual abstinence periods.

OBJECTIVE: Metabolomic profiling of seminal plasma has been suggested as a possible approach for a fast and non-invasive male infertility evaluation diagnosis. However, metabolomics profiles in normozoospermic men have not been thoroughly investigated, and the influence of ejaculation-abstinence has not been described. To provide interim reference values and find associations between the metabolomics profiles of human seminal plasma and length of ejaculation-abstinence period in normozoospermic men. STUDY DESIGN: Semen samples collected after long (4-7 days) and short abstinence (2 h) from 31 normozoospermic males were assessed for routine quality parameters before the seminal plasma was separated by centrifugation. Metabolomics profiles of the seminal plasma were then determined using untargeted Nuclear Magnetic Resonance Spectroscopy. RESULTS: In total, 30 metabolites were identified. Pyruvate showed a higher concentration, while fructose, acetate, choline, methanol, N-acetylglucosamine, O-acetylcarnitine, uridine, and sn-glycero-3-phosphocoline showed lower concentrations in samples collected after short abstinence (vs. long). All metabolites showed lower absolute amounts (volume × concentration) following shorter abstinence. However, the lower sperm concentration in samples collected after short abstinence resulted in higher absolute amounts of pyruvate and taurine per spermatozoa: pyruvate 1.92 (1.12-3.87) vs. 1.29 (0.83-2.62) (P < 0.001) and taurine 0.58 (0.36-0.92) vs. 0.43 (0.28-0.95) (P < 0.05) ng/106 spermatozoa. Simultaneously, there was a higher percentage of progressively motile spermatozoa in samples collected after the short abstinence. CONCLUSION: The generally lower concentrations of seminal metabolites after short abstinence periods may be related to the shorter time available for secretion and collection of these metabolites by the accessory glands and the epididymides. The concomitant lower number of spermatozoa in the second ejaculate resulted in increased absolute amounts of pyruvate and taurine per spermatozoa, accompanied by increased spermatozoa motility in these samples. The simultaneous increase in percentages of motile spermatozoa and absolute amounts of pyruvate and taurine per spermatozoa after shorter abstinence might indicate that these two metabolites play a more critical role in sperm motility, which should be further investigated in future studies.

Cut-off values for normal sperm morphology and toxicology for automated analysis of rat sperm morphology and morphometry.

We used automated sperm morphology analysis to investigate rat sperm morphometry and morphology in Sprague-Dawley and Wistar rats in three research centers to develop normal baseline values for sperm morphometry and to quantify the percentage of morphologically normal sperm in healthy rats. The participating centers were IRSN in Paris, France (Sprague-Dawley rats), University of the Western Cape, South Africa (Wistar rats) and Stellenbosch University (Wistar rats), South Africa. All three centers used identical sperm isolation techniques from the cauda epididymis, the same staining protocols, identical computer-aided sperm morphometry analysis (CASMA) software and microscopes with similar optics. With CASMA, fully automated analysis of the different parts of stained sperm, e.g., head, acrosome, mid-piece, can be performed, many sperm morphometric features can be measured accurately and eventually normal sperm morphology can be defined. We found that it is possible to distinguish sperm morphometric characteristics of Sprague-Dawley and Wistar rats. We also developed cut-off values for evaluating the percentage normal sperm in these two rat strains using the automatic analysis mode. Normal sperm morphology varied between 67 and 74% by contrast with previous findings of > 90%.

Ultraviolet Light Induced Generation of Reactive Oxygen Species.

As ultraviolet (UV) radiation is naturally and ubiquitously emitted by the sun, almost everyone is exposed to it on a daily basis, and it is necessary for normal physiological function. Human exposure to solar UV radiation thus has important health implications. The generation of reactive oxygen species (ROS) by UV radiation is one of the mechanisms through which UV light can manifest its possible detrimental effects on health. When an imbalance develops due to ROS generation exceeding the body's antioxidant defence mechanisms, oxidative stress can develop. Oxidative stress can lead to cellular damage (e.g. lipid peroxidation and DNA fragmentation), apoptosis and cell death. Broadly UV can induce ROS by affecting the cellular components directly or by means of photosensitization mechanisms. More specifically UV light can induce ROS by affecting the enzyme catalase and up-regulating nitric oxide synthase (NOS) synthesis. It may also cause a decrease in protein kinase C (PKC) expression leading to increased ROS production. UVR is capable of modifying DNA and other chromophores resulting in elevated ROS levels. The effects of raised ROS levels can vary based on the intracellular oxidant status of the cell. It is therefore important to protect yourself against the potentially harmful effects of UV light as it can lead to pathological UV-induced ROS production.

Are oxidative stress markers associated with unexplained male infertility?

Male infertility can be responsible for up to 20% of the cases attending fertility consultation facilities; nonetheless, the underlying molecular mechanisms that could explain it are still elusive. Therefore, we aimed to evaluate conventional and functional parameters of semen samples from patients who presented with male infertility of unknown origin. Conventional semen parameters and functional parameters (i.e. intracellular reactive oxygen species production, mitochondrial membrane potential, sperm chromatin structure assay, sperm membrane lipid peroxidation and antioxidant capacity of seminal plasma) were evaluated on semen samples from 54 healthy donors, 23 patients with idiopathic infertility and 34 fertile controls. No significant differences were observed in the conventional seminal parameters between the fertile and infertile men. However, increased intracellular reactive oxygen species (ROS) production and DNA fragmentation were observed in the infertile patients compared to the fertile group. Alterations in intracellular ROS production and DNA fragmentation could be associated with male idiopathic infertility. These parameters could eventually distinguish both groups more accurately than the conventional parameters. Our current results are encouraging, and the efficacy of these parameters in the clinical settings needs to be further assessed to establish their predictive potential as a marker of unexplained male infertility.

Large volume cryoprotectant-free vitrification: an alternative to conventional cryopreservation for human spermatozoa.

Vitrification is a simple and cost-effective method for the storage of human spermatozoa without the use of conventional cryoprotectants, by plunging the sperm suspension directly into liquid nitrogen. As a result, solidification of living cells without the formation of ice crystals is achieved during cooling. This study aimed to compare cryoprotectant-free vitrification to conventional cryopreservation protocols. Semen samples (n = 35) were collected from patients seeking diagnostic assistance at the Reproductive and Endocrine Unit at Steve Biko Academic Hospital. Samples were processed using a discontinuous density-gradient centrifugation method. Washed samples were split into two aliquots and cryopreserved either by means of cryoprotectant-free vitrification (sucrose + 1% albumin) or conventional slow freezing (TEST-yolk buffer). Post-thawing, the sperm motion parameters, mitochondrial membrane potential (Δψm) and DNA fragmentation were compared between the two groups. No significant differences were observed in the sperm motility parameters (P > 0.05). Significantly higher percentages of Δψm (11.99% ± 4.326% versus 6.58% ± 1.026%; P < 0.001) and lower percentages of DNA fragmentation (2.79% ± 1.017% versus 3.86% ± 1.38%; P < 0.01) were observed when comparing cryoprotectant-free vitrification to conventional cryopreservation. Cryoprotectant-free vitrification is a rapid and promising alternative to conventional methods resulting in good-quality spermatozoa post-thaw.

In vitro effects of nicotine on human spermatozoa.

Washed human spermatozoa from 12 normozoospermic donors were treated with different concentrations of nicotine 0.1, 1.0, 5.0 and 10.0 mm and were compared to spermatozoa suspended in nutrient medium only (control). Computer-aided sperm analysis was used to assess sperm kinematic properties after 30, 60, 120 and 180 min of incubation. Viability was assessed by means of a dye exclusion staining technique (eosin/nigrosin), while acrosome-reacted cells were identified under a fluorescent microscope using fluorescein isothiocyanate-Pisum sativum agglutinin as a probe. Nicotine significantly reduced total motility, progressive motility, curvilinear velocity, amplitude of lateral head displacement, beat cross-frequency, viability and caused spontaneous acrosome reaction at concentrations of ≥5.0 mm after 2 and 3 h of exposure. Nicotine concentrations of 0.1 and 1.0 mm had no significant effect (P < 0.05) on spermatozoa except that 1.0 mm significantly decreased (P < 0.05) sperm progressive motility at 2 and 3 h of incubation as well as viability after 3 h of incubation. This study concludes that the occurrence of high levels of nicotine in the body and seminal fluid might adversely affect fertilisation capacity of human spermatozoa through a mechanism that involves decreased motility, viability and premature induction of the acrosome reaction.

Revisiting the assessment of semen viscosity and its relationship to leucocytospermia.

With infertility challenges posing an obstacle to many couples, the extension of variables to assess male fertility is an important line of research. At the Reproductive Biology Unit where the study was undertaken, a considerable proportion of male patient's seeking fertility assessment presented with hyperviscous semen samples and elevated concentrations of leucocytes. Despite viscosity being included as part of a routine spermiogram, it raises a considerable amount of concern as it is assessed semiquantitatively. The study was undertaken to evaluate the quantification of semen viscosity in centipoise (cP) and to investigate whether a correlation exists between hyperviscosity and leucocytospermia. A total of 200 semen samples were assessed from a sample cohort of two population groups: 162 male patients undergoing fertility assessment and 38 volunteer donors. Semen viscosity was determined by measuring the filling time of a capillary-loaded Leja chamber and quantifying the viscosity in cP. Leucocytes were identified histochemically with a leucocyte peroxidase test. The viscosity when quantified in cP was significantly higher in the peroxidase positive sample group (9.01 ± 0.49 vs. 7.39 ± 0.23 cP; P < 0.005). The introduction of a more accurate method of quantifying viscosity may possibly help to identify, diagnose and treat patients suffering from leucocytospermia to ultimately enhance their fertility potential.

A red palm oil diet can reduce the effects of oxidative stress on rat spermatozoa.

Male Wistar rats (n = 54) received daily supplementation of red palm oil (RPO: 0, 2, 4 ml). Subgroups were subsequently injected with saline, cumene hydroperoxide (cHP, 10 µm) or t-butyl hydroperoxide (tbHP, 20 µm) over a 60-day period after which animals were sacrificed. Epididymal sperm motility, concentration, reactive oxygen species (ROS), lipid peroxidation and enzymes were measured. Sperm concentration, motility, superoxide dismutase (SOD) concentration, glutathione (GSH) and catalase (CAT) activities were significantly lower, while dichlorofluorescein (DCF) and malondialdehyde (MDA) were higher in sperm of hydroperoxide-treated animals compared to controls (P < 0.05). DCF and MDA levels were significantly lower, while SOD, CAT and GSH were significantly higher in the sperm of rats supplemented with RPO in combination with hydroperoxide treatment when compared to those receiving hydroperoxide and no RPO supplementation (P < 0.05). Moreover, the DCF, SOD, CAT and GSH levels in the RPO hydroperoxide groups did not differ from control values (P > 0.05). RPO supplementation can successfully attenuate the oxidative stress-induced sperm damage due to organic hydroperoxide exposure. We therefore propose that a daily intake of RPO supplement to the diet might be helpful in protecting males against the adverse effects of high ROS in sperm function and help preserve fertility.

Effects of H(2)O(2) exposure on human sperm motility parameters, reactive oxygen species levels and nitric oxide levels.

Research has revealed that reactive oxygen species (ROS) negatively affect sperm function, both in vivo and in vitro. Sperm preparation techniques for assisted reproductive technologies (ART) are potential causes for additional ROS production. This study aimed to correlate the concentration of exogenous H(2)O(2) with sperm motility parameters and intracellular ROS and nitric oxide (NO) levels to reiterate the importance of minimising ROS levels in ART. Human spermatozoa from 10 donors were incubated and exposed to different exogenous H(2)O(2) concentrations (0, 2.5, 7.5 and 15 mum). Subsequently, motility was determined using computer-aided semen analysis, while ROS (2,7-dichlorofluorescin diacetate) and NO (diaminofluorescein-2/diacetate) were analysed using fluorescence-activated cell sorting. Results showed that H(2)O(2) did affect the sperm parameters. Exogenous H(2)O(2) was detrimental to motility and resulted in a significant increase in overall ROS and NO levels. A significant increase in static cells was seen as well. It is important to elucidate the mechanisms between intracellular ROS levels with sperm motility parameters. While this experiment demonstrated a need to reduce exogenous ROS levels during ART, it did not illustrate the cause and effect relationship of intracellular ROS and NO levels with sperm motility. Further research needs to be conducted to define a pathological level of ROS.

Morphometric dimensions of the human sperm head depend on the staining method used.

BACKGROUND: Assessment of sperm morphology (including morphometry) is extensively used to determine one of the qualities of a semen sample and depends on the differential staining of spermatozoa. A staining technique should cause as little change to sperm dimensions and form as possible in order to reliably evaluate the morphometric features of the sperm. Various staining techniques have been employed, but only a few have been recommended by the World Health Organization and are amenable to automated sperm morphometry analysis. Our study was aimed at comparing the effect of three staining techniques [Papanicolaou (PAP), Rapidiff (RD) and SpermBlue (SB)] on human sperm head dimensions and to compare these with the head dimensions in fresh semen. METHODS: Smears made from human semen samples (n = 24) were stained according to the three staining techniques and sperm head morphometry was assessed with the Sperm Class Analyzer. Head dimensions of fresh spermatozoa were measured with a digital calliper on a computer screen. The minimum number of spermatozoa to be analyzed to represent the sperm population and the degree of inter-laboratory variation were determined. Electron micrographs from the same semen samples were used to determine the actual acrosome coverage of the spermatozoa in the semen (n = 7) in order to verify the results of the automatic analyses. RESULTS: The osmolality of human semen differs from that of the RD and PAP fixatives and stains, but is more similar to the SB fixative and stain. At least 100 spermatozoa should be analyzed to include a representative sample of the sperm population. RD caused sperm heads to swell, PAP caused them to shrink and SB had no significant effect on sperm head dimensions when compared with spermatozoa in fresh semen. Very little inter-laboratory variations were found. The percentage acrosome coverage was significantly different between the three staining techniques, as well as between the RD and PAP stains and the manual measurements obtained using the electron micrographs. CONCLUSIONS: Different staining techniques change the morphometric dimensions of the human sperm head, probably due to the fact that either the fixatives or stains are not iso-osmotic in relation to human semen. Since these changes in sperm head dimensions are not uniform, care should be taken when selecting a staining technique. Ideally, stained spermatozoa should have dimensions as close to spermatozoa in fresh semen as possible, as was found with the SB staining method, resulting in accurate evaluations of sperm head morphometry.

The in vitro effects of melatonin on human sperm function and its scavenging activities on NO and ROS.

Various systems of antioxidants exist endogenously in the body to help protect it against free radical damage by scavenging excessive ROS and RNS. Melatonin, a hormone secreted by the pineal gland, and responsible for controlling the circadian rhythm, is one such endogenous antioxidant. Melatonin has been reported to be present in human seminal fluid, but its antioxidant activities in semen are rather contradictory. This study aimed at establishing the effects of melatonin treatment on human spermatozoa. Spermatozoa were incubated with 2 mm melatonin (120 min, 37 degrees C, 5% CO(2)) after which motility parameters were measured by computer aided motility analysis, while cell viability (PI), intracellular NO (DAF-2/DA) and ROS (DCFH-DA) were assessed using flow cytometry. In vitro melatonin treated samples (n = 12) showed a significantly higher percentage of motile, progressive motile and rapid cells, while simultaneously reducing the number of nonviable spermatozoa when compared with the control. Endogenous NO was significantly decreased, but no effect was observed on ROS levels. From these results, it can be concluded that melatonin was able to directly or indirectly scavenge NO, as indicated by the reduction in 4,5-diaminofluorescein-2/diacetate fluorescence. Future studies will indicate whether melatonin treatment during sperm preparation techniques could protect spermatozoa from excessive NO production.

Effects of tumour necrosis factor alpha and interleukin-6 on progesterone and calcium ionophore-induced acrosome reaction.

For human spermatozoa to successfully fertilize the oocyte, they need to undergo a timely acrosome reaction (AR). Factors which disturb the AR may lead to fertilization failure. The objective of this study was to investigate the effects of two cytokines namely tumour necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) on the spontaneous, calcium ionophore-induced and progesterone-induced human sperm AR. Twenty-two normal semen samples were treated with increasing concentrations of TNF-alpha and IL-6 after spermatozoa were isolated by a double wash swim-up method. The AR was induced by calcium ionophore A23187 and progesterone. The AR was determined by using fluorescein isothiacyanate Pisum sativum agglutinin and observed under fluorescence microscope. Both TNF-alpha and IL-6 could decrease the spontaneous, ionophore and progesterone-induced AR (p < 0.05) in a dose-dependent manner. TNF-alpha showed a more potent inhibiting effect than IL-6 by inhibiting the AR at lower concentrations. This study has demonstrated that TNF-alpha and IL-6 play a role in inhibiting both the non-physiological as well as physiologically elicited AR by calcium ionophore and progesterone respectively.

Phosphatidylinositol 3-kinase inhibition enhances human sperm motility and sperm-zona pellucida binding.

Various signalling pathways are involved in the regulation of sperm motility, capacitation, acrosome reaction and sperm-zona binding. Recent data pointed out an important role for phosphatidylinositol 3-kinase (PI3K) in human sperm motility. However, no study as of yet has been carried out to determine the effect of sperm treatment with the PI3K inhibitor LY294002 on other sperm parameters. In the present study, we investigated the role of PI3K on human sperm motility, acrosome reaction and sperm-oocyte binding by using this inhibitor. We demonstrate that in vitro incubation of washed unselected spermatozoa with LY294002 increased the percentage motility and progressive motility in asthenozoospermia patients as evaluated by computer-aided sperm analysis. The compound furthermore did not influence the acrosome reaction, whilst it (further) slightly enhanced sperm-oocyte binding. Our results therefore imply that PI3K negatively affects sperm motility and oocyte binding and might suggest a possible therapeutic role for PI3K inhibitors in the treatment regime for asthenozoospermia.

Extracellular signal-regulated kinase activation involved in human sperm-zona pellucida binding.

In a previous study involving the inhibition the mitogen-activated protein kinase (MAPK), extracellular signal regulated kinase (ERK), we found that the very specific MAPK kinase (MEK) inhibitor, PD098059, inhibited the zona pellucida (ZP) induced acrosome reaction. As an intact acrosome on the spermatozoa is a prerequisite in ensuring tight binding to the ZP, we investigated the zona binding potential of spermatozoa after PD098059 treatment of sperm, followed by exposure to solubilised human ZP and calcium ionophore (A23187). PD098059 treated spermatozoa, exposed to solubilised ZP, bound significantly more to the ZP, as compared to control spermatozoa also exposed to solubilised ZP (26.5 +/- 3.7 vs. 13.8 +/- 2.8, P < 0.05). No significant differences in binding to the ZP were observed between PD098059 treated and untreated sperm populations after A23187 exposure. These results can be interpreted to support the idea that the ZP-induced AR is the physiologically relevant exocytotic event, as it is the ZP-induced AR, and not the spontaneous (culture medium) or A23187 induced AR, that appears to be mediated through an ERK-mediated signal transduction process.

The zona pellucida-induced acrosome reaction of human spermatozoa involves extracellular signal-regulated kinase activation.

Extracellular signal-regulated kinases (ERKs), belonging to the family of mitogen-activated protein kinases (MAPKs), are cytoplasmic and nuclear serine/threonine kinases involved in the signal transduction of several extracellular effectors. Recent evidence indicates the presence of p21 Ras and the phosphorylation of ERK1 and ERK2, suggesting the occurrence of the Ras/ERK cascade in mammalian spermatozoa. The present article describes the biological role of ERK during the acrosome reaction of human spermatozoa on stimulation with zona pellucida (ZP). The mitogen-activated protein-kinase inhibitor PD098059 was used as a pharmacological tool to study the involvement of extracellular signal-regulated kinases in the induction of the acrosome reaction in human spermatozoa. This compound significantly inhibited the acrosome reaction induced by both ZP and the calcium ionophore A23187. These results suggest that ERKs are involved in the signal transduction pathway through which ZP stimulation works during the process of fertilization.

The effect of selenium supplementation during the early post-mating period on embryonic survival in sheep.

The effect of selenium (Se) supplementation of ewes with blood Se concentrations ranging between 100-200 ng/ml on embryonic survival during the early post-mating period (days 15-35) was studied in 4 trials. In the 1st 2 trials 137 ewes were used in 1991 and 118 in 1992. After being mated as a single flock, these ewes were stratified randomly into 3 groups. One group served as a control, the 2nd was injected with 1 ml Deposel (containing 50 mg Se as Ba selenate) and the 3rd group injected with 1 ml containing 1 mg Se as Na selenite. During 1991, supplementation was administered immediately after the mating period. It was postponed by 14 days in 1992. Parenteral Se supplementation reduced (p < 0.10) the number of ewes that lambed by > 19% during 1991 but not during 1992. The number of ewes producing twins was unaffected. In Trials 3 and 4 there was a consistent indication that parenteral Se supplementation of pregnant ewes between 15-35 days after mating resulted in a reduced (22-40%) embryonic survival rate, although significant (p < or = 0.10) differences were only observed after the pooling of treatments receiving parenteral Se supplementation. Drenching of ewes with 50 mg Se as Na selenite resulted in a similar tendency. Biochemical appraisal of the blood, kidney and liver Se status of ewes failed to reveal toxic levels. The possible mechanisms involved in impaired embryonic survival are unclear. Supplementation of ewes during the 1st month of pregnancy with parenteral Se preparations is not recommended.

An assessment of the toxicity of parenteral treatment with copper EDTA and copper heptonate in sheep.

The toxicity of 2 parenteral copper (Cu) supplements was investigated. Di-sodium copper ethylene diamino tetra acetate (Cu EDTA) and Cu heptonate were administered to sheep (n = 9) by a single subcutaneous injection at a concentration of 0,2, 1 and 2 mg Cu/kg each (Trial 1.) Nine sheep were untreated and served as controls. The same treatments were applied to 2 sheep each (Trial 2) with the addition of 3 mg Cu/kg live body mass as Cu heptonate, and Cu heptonate administered intravenously at rates of 0,2, 0,4 and 0,6 mg Cu/kg live body mass. In Trial 1, 67% of the sheep treated with Cu EDTA at 2 mg Cu/kg live body mass died within 3 to 17 d after treatment, while no mortalities occurred in sheep where Cu heptonate was administered at the same dosage rate and even at 3 mg Cu/kg live body mass (P < or = 0,01). Post-mortem examination suggested acute Cu toxicity in all cases. Liver Cu concentrations were markedly increased (P < or = 0,05) by both supplements in groups of 3 treated sheep slaughtered over a 3-month period compared to control animals. The liver Cu concentrations of sheep that succumbed to Cu toxicity were within the normal range of 100 to 450 mg/kg DM. Results from Trial 2 suggested that the 2 sheep treated with 2 mg Cu/kg live body mass as Cu EDTA, experienced a haemolytic crisis between 5 and 11 d after treatment, resulting in the death of one of these sheep. The haemolytic crisis was characterised by a severe decrease in haemoglobin concentration and haematocrit.(ABSTRACT TRUNCATED AT 250 WORDS)