Differential activities of malate and isocitrate NAD(P)-dependent dehydrogenases are involved in the induction of capacitation and acrosome reaction in cryopreserved bovine spermatozoa

Quercetin and Naringenin Provide Functional and Antioxidant Protection to Stored Boar Semen

In this study, we evaluated the impact of 5-50 μM quercetin (QUE) and naringenin (NAR) on extended boar spermatozoa in the BTS (Beltsville Thawing Solution) medium for 72 h. Spermatozoa motion, membrane, acrosome, and DNA integrity were investigated immediately after sample dilution (0 h) as well as after 24 h, 48 h, and 72 h of semen storage. Furthermore, reactive oxygen species (ROS) and superoxide production, as well as the extent of oxidative damage to the sperm proteins and lipids, were assessed to determine the potential of QUE and NAR to prevent a potential loss of sperm vitality due to oxidative stress development. Our results indicate that the most notable parameter influenced by QUE was the mitochondrial activity, which remained significantly higher throughout the experiment (p < 0.001 and p < 0.0001; 10 μM), and which correlated with the most prominent maintenance of sperm motility (p < 0.01, 48 h; p < 0.05, 72 h). A significant membrane stabilization (p < 0.01, 24 h and 48 h; p < 0.0001, 72 h) and prevention of lipid peroxidation (p < 0.05, 24 h and 48 h; p < 0.01, 72 h) was primarily observed following administration of 10 and 25 μM NAR; respectively. Administration of 10 μM QUE led to a significant decrease of superoxide (p < 0.0001, 48 h and 72 h) while the most notable decline of ROS generation was recorded in the case of 10 and 25 μM NAR (p < 0.001). This study may provide new information on the specific mechanisms of action involved in the favorable effects of natural biomolecules on spermatozoa.

Metabolomics analysis of seminal plasma in patients with idiopathic Oligoasthenoteratozoospermia using high-resolution NMR spectroscopy

BACKGROUND

Male infertility is a global health issue caused by a combination of different factors. Specialists generally rely on semen analysis to diagnose male infertility. However, it is known that diagnostic semen analysis fails to identify about 50% of male infertility disorders. Recently, metabolomics has been proven to be a powerful technique for the diagnosis of different diseases.

OBJECTIVE

To determine whether metabolites could be used as potential biomarkers for the diagnosis of male factor infertility through comparing seminal plasma samples from infertile men with oligoasthenoteratozospermia (OAT) and samples from normozoospermic controls.

MATERIALS AND METHODS

This study utilized high-resolution ¹ H NMR spectroscopy to reveal whether the metabolomic changes of seminal plasma obtained from 31 patients with oligoasthenoteratozospermia (OAT) are different from the ones obtained from 28 normozoospermic controls.

RESULTS

Multivariate statistical analysis of NMR data concluded that the metabolomic profile of samples from patients with OAT exhibits statistically significant differences when compared to the controls. The differences were based on the metabolites lactate, citrate, lysine, arginine, valine, glutamine, creatinine, α-ketoglutaric acid, spermine, putrescine, and tyrosine. Except the tyrosine, levels of the above metabolites were significantly decreased in patients with OAT compared to the controls. The levels of citrate, choline, spermine, putrescine, α-ketoglutaric acid, valine, and tyrosine were significantly different (p < 5 × 10^-4 ) between two groups. On the other hand, levels of lactate, creatinine, lysine, arginine, and glutamine were also statistically significant (0.001 < p < 0.05). However, considering the p-values, the physiological relevance of these metabolites may be lower when compared to the others. A PLS-DA model built on the NMR data achieved 89.29% sensitivity and 93.55% specificity results in a leave-one-out cross-validation process.

DISCUSSION AND CONCLUSION

¹ H NMR spectroscopy-based metabolomic analysis could be used as a diagnostic tool for the diagnosis of oligoasthenoteratozospermia.

Decrease in the cytosolic NADP+-dependent isocitrate dehydrogenase activity through porcine sperm capacitation

In order to understand the molecular mechanisms involved in the sperm capacitation, we have identified the proteins tyrosine-phosphorylated during the capacitation especially in conjunction with the regulation of the levels of reactive oxygen species (ROS) in sperm. In the present study, the effects of the tyrosine phosphorylation of cytosolic NADP⁺-dependent isocitrate dehydrogenase (IDPc) on its catalytic activity and on the levels of ROS in sperm have been studied. The tyrosine phosphorylated IDPc showed a significantly lowered enzymatic activity. The immunocytochemical analyses using the highly specific antisera against IDPc revealed that IDPc was mainly localized to the principal piece of the porcine sperm flagellum. As IDPc is one of the major NADPH regenerating enzymes in porcine sperm, it is strongly suggested that the decrease in IDPc activity is involved in the increased levels of ROS, which results in the induction of hyperactivated flagellar movement and capacitation.

Progesterone causes metabolic changes involving aminotransferases and creatine kinase in cryopreserved bovine spermatozoa

Progesterone (P4) is capable of inducing acrosome reaction in many species. The objective of this study was to determine the activity of enzymes involved in metabolism that contribute to the redox state and supply energy for acrosome reaction in cryopreserved bull spermatozoa. To accomplish this aim, acrosome reaction was induced by P4 in capacitated and non-capacitated samples. Alanine and aspartate aminotransferases (ALT, AST) and creatine kinase (CK) activities were measured spectrophotometrically at 340 nm after acrosome reaction with P4. Oxygen consumption was measured polarographically. ALT and AST activities increased by the addition of P4 capacitated and non-capacitated samples. P4 addition provoked an increase in CK activity in non-capacitated spermatozoa compared to heparin capacitated spermatozoa with or without P4 addition. P4 increased oxygen consumption, the percentage of acrosome reacted spermatozoa as well as the absence of acrosome integrity in both capacitated and non-capacitated bovine spermatozoa, but oxygen consumption in P4 samples was significantly lower than in heparin capacitated spermatozoa (P<0.05). Acrosome reaction induction by P4 required different creatine kinase activity with the same oxygen consumption and transaminases level to maintain oxidative metabolism and redox state through reducing equivalents transfer between cytosolic and mitochondrial compartment. In conclusion, P4 induces a lower oxidative metabolism during acrosome reaction in bovine cryopreserved spermatozoa, compared to heparin induced capacitation process.

Effect of Solanum surattense seed on the oxidative potential of cauda epididymal spermatozoa

OBJECTIVE

To evaluate the effect of aqueous seed extract of Solanum surattense (S. surattense) on the oxidative potential of cauda epididymal spermatozoa.

METHODS

S. surattense seed extract was orally administered at the dosage of 10 mg/kg b.w. for 15 days, after which aspartate transferase (AST), alanine transferase (ALT), glutamate dehydrogenase (GDH), citric acid and iso-citrate dehydrogenase (ICDH) were assayed.

RESULTS

The activity levels of the enzymes AST and ALT, which are considered to be the androgenicity in the sperm suspension, were depleted in the extract fed rats. The activity level of the enzyme ICDH, was reduced significantly in the treated group (P<0.001).

CONCLUSIONS

It can be concluded that the oral administration of the aqueous seed extract of S. surattense can deplete the oxidative stress of cauda epididymal spermatozoa in albino rats.

Discovery of predictive biomarkers for litter size in boar spermatozoa

Conventional semen analysis has been used for prognosis and diagnosis of male fertility. Although this tool is essential for providing initial quantitative information about semen, it remains a subject of debate. Therefore, development of new methods for the prognosis and diagnosis of male fertility should be seriously considered for animal species of economic importance as well as for humans. In the present study, we applied a comprehensive proteomic approach to identify global protein biomarkers in boar spermatozoa in order to increase the precision of male fertility prognoses and diagnoses. We determined that l-amino acid oxidase, mitochondrial malate dehydrogenase 2, NAD (MDH2), cytosolic 5'-nucleotidase 1B, lysozyme-like protein 4, and calmodulin (CALM) were significantly and abundantly expressed in high-litter size spermatozoa. We also found that equatorin, spermadhesin AWN, triosephosphate isomerase (TPI), Ras-related protein Rab-2A (RAB2A), spermadhesin AQN-3, and NADH dehydrogenase [ubiquinone] iron-sulfur protein 2 (NDUFS2) were significantly and abundantly expressed in low-litter size spermatozoa (>3-fold). Moreover, RAB2A, TPI, and NDUFS2 were negatively correlated with litter size, whereas CALM and MDH2 were positively correlated. This study provides novel biomarkers for the prediction of male fertility. To the best of our knowledge, this is the first work that shows significantly increased litter size using male fertility biomarkers in a field trial. Moreover, these protein markers may provide new developmental tools for the selection of superior sires as well as for the prognosis and diagnosis of male fertility.

Efficacy of Withania somnifera on seminal plasma metabolites of infertile males: a proton NMR study at 800 MHz

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Indian systems of medicine use roots of Withania somnifera for impotence, infertility treatment, stress, and the aging process. Although Withania somnifera improves semen quality by regulating reproductive hormone levels and oxidative stress, the molecular mechanism is not clear.

AIM OF THE STUDY

Our study uses high-resolution Nuclear Magnetic Resonance (NMR) spectroscopy to explore the scientific basis to reveal the pre- and post-treatment efficacy of Withania somnifera on seminal plasma of infertile men-which remains unexplored to date.

MATERIALS AND METHODS

A total of 180 infertile male patients were administered Withania somnifera root powder at the rate of 5 g/d for a 3-month period. The study included age-matched, healthy men as a control (n=50) group. Proton NMR spectroscopy was used to measure lactate, alanine, glutamate, glutamine, citrate, lysine, choline, glycerophosphocholine (GPC), glycine, tyrosine, histidine, phenylalanine, and uridine in all seminal plasma samples. To appraise infertility levels, we also measured sperm concentration, motility, lipid peroxide, and hormonal perturbation.

RESULTS

Withania somnifera therapy repairs the disturbed concentrations of lactate, alanine, citrate, GPC, histidine, and phenylalanine in seminal plasma and recovers the quality of semen of post-treated compared to pre-treated infertile men. Serum biochemistry was also improved over post-therapy in infertile men. Our findings reveal that Withania somnifera not only reboots enzymatic activity of metabolic pathways and energy metabolism but also invigorates the harmonic balance of seminal plasma metabolites and reproductive hormones in infertile men.

CONCLUSION

The results suggest that Withania somnifera may be used as an empirical therapy for clinical management and treatment of infertility.

Acrosin activity regulation by protein kinase C and tyrosine kinase in bovine sperm acrosome exocytosis induced by lysophosphatidylcholine

Acrosin is an important proteolytic enzyme that is capable of hydrolysing the zona pellucida in bovine oocyte. Lysophosphatydic acid (LPA) derivated from lysophosphatidylcholine (LPC) is known to trigger the acrosome exocytosis. The present study was aimed at examining the acrosin activity variations in LPC-induced acrosome exocytosis and its regulation by tyrosine kinase, protein kinase C (PKC) and voltage-dependent calcium channels (VDCC) in spermatozoa previously capacitated with heparin or quercetin. The enzyme activities were spectrophotometrically measured using N-α-benzoyl-DL-arginine p-nitroanilide as an acrosin-specific substrate. The capacitation and acrosomal reaction were evaluated by chlorotetracycline assay, and the viability and acrosome integrity were evaluated by the trypan blue stain/differential interference contrast. It was observed that LPC induced acrosome exocytosis and increased the activity of acrosin in spermatozoa previously capacitated with heparin. In heparin/LPC-treated samples, it was observed that the inhibition of tyrosine kinase and PKC blocked the acrosome exocytosis and the acrosin activity (p < 0.05). Under these conditions, in heparin-capacitated spermatozoa, the LPC provokes an acrosin activity increase that is independent of calcium influx through VDCC Type L. In cryopreserved bovine spermatozoa, LPC might require modulation, mainly tyrosine kinase participation with respect to PKC activity to induce acrosome exocytosis and increase acrosin activity.

Quantitative expression of candidate genes for developmental competence in bovine two-cell embryos

Only competent oocytes are able to undergo complete maturation and normal embryonic development. Therefore, the identification of genes that are differentially expressed in competent oocytes would contribute to our understanding of the factors controlling competency. It is well known that time of cleavage after insemination in vitro is highly correlated with embryonic developmental potential and this can be used to distinguish between oocytes of different quality. The main objective of this study was to identify genes associated with competency and rapid cleavage. We examined the expression of 16 candidate genes (IDH, YEAF Cathepsin B, RAD50, TCP1 NCOR1, HUEL, STK6, ZNF403, AOP2, EEF1A1, Hsp90, Hsp40, AKR1B1, PGRMC1, and DMRT2) in early and late cleaving embryos, by real time PCR. These transcripts were derived from previous study in our laboratory using cDNA coming from a suppressive subtraction hybridization (SSH) between early cleaving versus late cleaving embryos spotted on a microarray slide. Of the 16 genes evaluated, 3 (IDH, YEAF, and H2A) showed statistical difference (P < 0.05) between early and late cleaving embryos. However, some genes such as Cathepsin B (P = 0.0677), RAD50 (P = 0.0899), and TCP1 (P = 0.0824) tended to show higher expression in the early cleaving than in the late cleaving embryo. In conclusion, we have identified three genes (YEAF, IDH, H2A) that were differentially expressed in the early cleaving embryos, and their expression can be associated with greater developmental competence.