Search

Reactive Oxygen Species (ROS) play an important role in sperm physiology. They are required in processes such as capacitation and fertilization. However, the exposure of spermatozoa to ROS generated from internal or external sources may create a potentially detrimental redox imbalance. Antioxidant supplementation in semen is now a rather common approach to protect spermatozoa from oxidative stress (OS) during their handling and/or cryopreservation. Supplementation with pterostilbene, a potent antioxidant, protects spermatozoa from OS and ameliorates their post-thawing characteristics and viability. In the present study, we used freezing/thawing as a model of natural ROS overproduction and investigated the molecular mechanisms modulated by pterostilbene. Specifically, bovine frozen/thawed spermatozoa were incubated with 10 or 25 μM pterostilbene for 60 min. Results have shown that in a dose-independent manner, pterostilbene decreased lipid peroxidation and increased intracellular GSH levels. Moreover, pterostilbene ameliorated energy production, as ATP and AMP/ATP levels were restored, and increased autophagy levels through AMP-activated protein kinase (AMPK) activation, which finally resulted in the inhibition of apoptotic cell death in bovine spermatozoa when exposed to OS. This study sheds light on spermatozoa redox state, the crosstalk between apoptotic and autophagic pathways, and its role in determining the beneficial or detrimental effect of ROS in spermatozoa.

Erythropoietin (EPO), a hormone secreted mainly by the kidney, exerts its biological function by binding to its cell-surface receptor (EpoR). The presence of EPO and EpoR in the male and female reproductive system has been verified. Therefore, some of the key properties of EPO, such as its antioxidant and antiapoptotic effects, could improve the fertilizing capacity of spermatozoa. In the present study, the effect of two different concentrations of EPO (10 mIU/μL and 100 mIU/μL) on bovine sperm-quality parameters was evaluated during a post-thawing 4-h incubation at 37 °C. EPO had a positive effect on sperm motility, viability, and total antioxidant capacity. Moreover, EPO inhibited apoptosis, as it reduced both BCL2-associated X apoptosis regulator (Bax)/B-cell lymphoma 2 (Bcl-2) ratio and cleaved cysteine-aspartic proteases (caspases) substrate levels in a dose-dependent manner. In addition, EPO induced sperm capacitation and acrosome reaction in spermatozoa incubated in capacitation conditioned medeia. These results establish a foundation for the physiological role of EPO in reproductive processes and hopefully will provide an incentive for further research in order to fully decipher the role of EPO in sperm physiology and reproduction.

The imbalance between clot formation and fibrinolysis is mainly attributed to increased levels of plasminogen activator inhibitor type 1 (PAI-1), an inhibitor of fibrinolysis closely involved in inflammatory responses such as septic shock. This increase is mediated by many factors, including reactive oxygen species (ROS). The present study was designed to evaluate the prophylactic effect of crocin, a potent natural antioxidant, on PAI-1 in the rat model of endotoxic shock. Lipopolysaccharide-infused rats (500 μg/kg) showed significant changes in thrombosis-related haematological parameters such as decrease of platelet blood counts and increase (7 fold) of PAI-1 concentration in blood plasma. No effect on t-PA activity was observed. Crocin administration in two different doses (10 mg/kg and 100 mg/kg) 30 min prior to the injection of LPS, inhibited the reduction of platelet counts and ameliorated the concentration of PAI-1 in the liver and the brain. Moreover, crocin inhibited the deposition of fibrin in the renal glomeruli. No significant changes were recorded in the healthy groups of crocin (10 mg/kg and 100 mg/kg) compared to the control group. These data demonstrate the potential of crocin to prevent LPS-induced organ injury and suggest it is worthwhile to investigate the use of antioxidants for the treatment of septicemia., (Copyright © 2019. Published by Elsevier Ltd.)

Background: Grape extracts of the Greek species Vitis vinifera possess potent antioxidant properties in vitro. The freeze/thaw process and the preparation of semen during assisted reproductive techniques can adversely affect the functional integrity of spermatozoa. The objective was to assess the effect of three different concentrations (1 μg ml(-1), 2 μg ml(-1) and 5 μg ml(-1)) of a polyphenol-rich grape pomace extract on motility, viability, acrosomal and lipid peroxidation status of thawed bovine spermatozoa after 2 and 4 hrs of incubation., Results: The results indicate that the percentage of "Rapid" spermatozoa remained significantly increased (p <0.05) in the presence of 5 μg ml(-1) of the extract, compared to the control after 2 hrs of incubation. Additionally, the incubation of spermatozoa with 2 μg ml(-1) and 5 μg ml(-1) of the extract for 2 hrs resulted in a significantly better maintenance of viable spermatozoa with intact acrosome (p <0.05). The other parameters did not show statistically significant changes. Moreover, the presence of 2 μg ml(-1) and 5 μg ml(-1) of the extract kept the levels of Malondialdehyde (MDA) production in significantly lower level, compared to the other groups, after 2 hrs and 4 hrs of incubation (p <0.05). Particularly, a dose-dependent effect was noticed after 2 hrs of incubation., Conclusions: Our results suggest that the grape pomace extract exerts a powerful antioxidant role, by suppressing lipid peroxidation, and provides protection in terms of motility and acrosomal integrity, which are correlated with in vivo fertility. The optimal extract concentration is 5 μg ml(-1).