Regulation of boar sperm functionality by the nitric oxide synthase/nitric oxide system.

PURPOSE: Nitric oxide (NO) is a free radical synthesized mainly by nitric oxide synthases (NOSs). NO regulates many aspects in sperm physiology in different species. However, in vitro studies investigating NOS distribution, and how NO influences sperm capacitation and fertilization (IVF) in porcine, have been lacking. Therefore, our study aimed to clarify these aspects. METHODS: Two main experiments were conducted: (i) boar spermatozoa were capacitated in the presence/absence of S-nitrosoglutathione (GSNO), a NO donor, and two NOS inhibitors, NG-nitro-L-arginine methyl ester hydrochloride (L-NAME) and aminoguanidine hemisulfate salt (AG), and (ii) IVF was performed in the presence or not of these supplements, but neither the oocytes nor the sperm were previously incubated in the supplemented media. RESULTS: Our results suggest that NOS distribution could be connected to pathways which lead to capacitation. Treatments showed significant differences after 30 min of incubation, compared to time zero in almost all motility parameters (P < 0.05). When NOSs were inhibited, three protein kinase A (PKA) substrates (~ 75, ~ 55, and ~50 kDa) showed lower phosphorylation levels between treatments (P < 0.05). No differences were observed in total tyrosine phosphorylation levels evaluated by Western blotting nor in situ. The percentage of acrosome-reacted sperm and phosphatidylserine translocation was significantly lower with L-NAME. Both inhibitors reduced sperm intracellular calcium concentration and IVF parameters, but L-NAME impaired sperm ability to penetrate denuded oocytes. CONCLUSIONS: These findings point out to the importance of both sperm and cumulus-oocyte-derived NO in the IVF outcome in porcine.

Total urokinase-type plasminogen activator (uPA) levels in seminal plasma are associated with positive assisted reproductive technology outcomes.

PURPOSE: The plasminogen/plasmin system is an important extracellular protease system whose function has been implicated in male reproductive function. However, its clinical relevance to fertility in human assisted reproduction technologies has not been systematically investigated. Here, we examined whether total and active populations of urokinase-type plasminogen activator (uPA) in human seminal plasma and spermatozoa are predictive of pregnancy outcome in couples undergoing insemination or intracytoplasmic sperm injection (ICSI). METHODS: Seminal samples from 182 men, 5 donors, 21 patients attending the clinic for infertility screening, and 156 for assisted reproduction technology (ART) treatment (insemination and ICSI), were evaluated. Total uPA in seminal plasma and spermatozoa as well as active uPA in seminal plasma were measured by ELISA. Sperm quality parameters and fertility outcomes following insemination or ICSI were correlated with the uPA values. RESULTS: Active uPA in seminal plasma was positively correlated to the volume of the ejaculate, total number of spermatozoa in the ejaculate, and total motility. However, these values were not prognostic of fertility outcomes. Total uPA in spermatozoa was inversely related to sperm concentration, total sperm in ejaculate, morphology, and total and progressive motility, and this measure was not related to fertility. Importantly, however, higher values of total uPA in seminal plasma were detected in cases that resulted in pregnancy compared to those that did not follow insemination and ICSI treatment. CONCLUSIONS: Taken together, these findings lay the foundation for further understanding the mechanism by which total uPA in seminal plasma affects fertility and how this marker can be used as a predictor of ART outcomes.

Assessment of two thawing processes of cryopreserved human sperm in pellets.

In this study, we evaluated the effects of the thawing methodology on sperm function after cryopreservation in pellets. We compared the use of two thawing procedures: method (1) maintaining pellet for 10 min in air at room temperature, then another 10-min period in air at 37°C followed by dilution in a thawing medium; and method (2) immersing the pellets directly in thawing medium at 37°C for 20 min. This procedure leads to a higher rate of temperature increase and a dilution of the glycerol present in the freezing medium. We analyzed the effect of the thawing procedure on sperm motility, viability, membrane lipid packing disorder, acrosome status, reactive oxygen species (ROS) level and sperm chromatin condensation. This study revealed a positive effect of the M2 thawing methodology on sperm parameters. The percentage of spermatozoa with fast-linear movement is increased (M1: 17.26% vs. M2: 28.05%, p<0.01), with higher viability (M1: 37.81% vs. M2: 40.15%, p<0.01) and less acrosome damage (M1: 40.44% vs. M2: 35.45%, p=0.02). We also detected an increase in the percentage of viable spermatozoa with low membrane lipid disorder (M1: 31.36% vs. M2: 33.17%, p=0.03) and a reduction in chromatin condensation (44.62 vs. 46.62 arbitrary units, p=0.02). Further studies will be necessary to evaluate the possible clinical applications.

Nitric oxide-targeted protein phosphorylation during human sperm capacitation.

Among many other molecules, nitric oxide insures the correct progress of sperm capacitation by mediating phosphorylation events. For a more comprehensive understanding of how this happens, we capacitated human spermatozoa from healthy men in the presence/absence of S-Nitrosoglutathione, a nitric oxide donor, two nitric oxide synthase inhibitors, NG-Nitro-L-arginine Methyl Ester Hydrochloride and Aminoguanidine Hemisulfate salt and, finally, with/without L-Arginine, the substrate for nitric oxide synthesis, and/or human follicular fluid. When analyzing the phosphorylation of protein kinase A substrates and tyrosine residues, we particularly observed how the inhibition of nitric oxide synthesis affects certain protein bands (~ 110, ~ 87, ~ 75 and ~ 62 kD) by lowering their phosphorylation degree, even when spermatozoa were incubated with L-Arginine and/or follicular fluid. Mass spectrometry analysis identified 29 proteins in these species, related to: spermatogenesis, binding to the zona pellucida, energy and metabolism, stress response, motility and structural organization, signaling and protein turnover. Significant changes in the phosphorylation degree of specific proteins could impair their biological activity and result in severe fertility-related phenotypes. These findings provide a deeper understanding of nitric oxide's role in the capacitation process, and consequently, future studies in infertile patients should determine how nitric oxide mediates phosphorylation events in the species here described.

Nitrite and Nitrate Levels in Follicular Fluid From Human Oocyte Donors Are Related to Ovarian Response and Embryo Quality.

Nitric oxide, a key regulatory molecule in the follicular fluid, has been suggested as a possible biomarker to predict ovarian response in stimulated cycles and the potential of the retrieved oocytes for developing high-quality embryos. Nevertheless, a consensus on whether or not nitric oxide can help in this context has not been reached. We simultaneously measured the oxidation products of nitric oxide, nitrite, and nitrate, via high-performance liquid chromatography (HPLC)-UV in follicular fluid samples from 72 oocyte donors. We found no associations of follicular fluid nitrite, nitrate, total nitric oxide, or nitrate/nitrite ratio with total or metaphase II (MII) oocyte yield. However, nitrite and nitrate levels were related to the yield of MII oocytes when this outcome was expressed as a proportion of all oocytes retrieved. The adjusted MII proportion in the lowest and highest nitrite levels were 68% (58-77%) and 79% (70-85%), respectively (p, linear trend = 0.02), whereas the adjusted MII proportion in extreme tertiles of nitrate levels were 79% (70-85%) and 68% (57-77%) (p, linear trend = 0.03). In addition, nitrate levels showed a suggestive inverse correlation with embryos with maximum or high potential of implantation (p = 0.07). These results suggest that the follicular fluid concentrations of nitrite and nitrate may be a useful tool in predicting how healthy oocyte donors respond to superovulation and the implantation potential of the embryos produced from their oocytes.

Physicochemical and Functional Characterization of Female Reproductive Fluids: A Report of the First Two Infants Born Following Addition of Their Mother's Fluids to the Embryo Culture Media.

Culture media supplemented with reproductive fluids (RF) have been used in livestock species, improving the efficiency and quality of in vitro produced embryos. However, usefulness in humans is still unknown. In this study, we collected human reproductive fluids (HRFs) ex vivo (from 25 patients undergoing abdominal hysterectomy plus bilateral salpingectomy) and in vivo (from 31 oocyte donors). Afterward, protocols to evaluate their osmolality, pH, total protein concentration, endotoxin level, and sterility were optimized, establishing security ranges for their use as natural additives. In addition, a functional assay was developed with bovine embryos grown in vitro in a medium supplemented with 1% of collected HRFs. Finally, a proof of concept was performed with six patients on post ovulation day 2 to evaluate the full-term viability of embryos grown in media supplemented with autologous uterine fluid, collected under in vivo conditions. Two of the embryos resulted in successful pregnancy and delivery of healthy babies. In conclusion, this study establishes a complete quality control sheet of HRFs as additives for embryo culture media and shows first preliminary data on obtaining healthy offspring derived from embryos grown in media supplemented with HRFs.

Dietary supplementation with docosahexaenoic acid (DHA) improves seminal antioxidant status and decreases sperm DNA fragmentation.

The purpose of this study was to evaluate the effect of docosahexaenoic acid (DHA) dietary supplementation on semen quality, fatty acid composition, antioxidant capacity, and DNA fragmentation. In this randomized, double blind, placebo-controlled, parallel-group study, 74 subjects were recruited and randomly assigned to either the placebo group (n=32) or to the DHA group (n=42) to consume three 500-mg capsules of oil per day over 10 weeks. The placebo group received 1,500 mg/day of sunflower oil and the DHA group 1,500 mg/day of DHA-enriched oil. Seminal parameters (semen volume, sperm concentration, motility, morphology, and vitality), total antioxidant capacity, deoxyribonucleic acid fragmentation, and lipid composition were evaluated prior to the treatment and after 10 weeks. Finally, 57 subjects were included in the study with 25 in the placebo group and 32 in the DHA group. No differences were found in traditional sperm parameters or lipid composition of the sperm membrane after treatment. However, an increase in DHA and Omega-3 fatty acid content in seminal plasma, an improvement in antioxidant status, and a reduction in the percentage of spermatozoa with deoxyribonucleic acid damage were observed in the DHA group after 10 weeks of treatment.

Effect of genistein supplementation of thawing medium on characteristics of frozen human spermatozoa.

In this study, we evaluated the effects of genistein supplementation of the thawing extender on frozen-thawed human semen parameters. We analyzed the effect of supplementation on sperm motility, capacitation (membrane lipid disorder), reactive oxygen species (ROS) generation, chromatin condensation and DNA damage. Using this preliminary information, it maybe possible to improve the cryopreservation process and reduce the cellular damage. We have confirmed that the isoflavone genistein (10 micromol L(-1)) has antioxidant properties on the frozen-thawed spermatozoa. This results in a decreased ROS production that shows a slight improvement in the sperm motility, and decreases the membrane lipid disorder and DNA damage caused by cryopreservation. These results suggest an effect of genistein on sperm functionality that could be of interest for assisted reproduction treatments using frozen-thawed human spermatozoa, but further studies will be necessary to confirm our findings and to evaluate the possible clinical applications.