THE IMPORTANCE OF ANTIOXIDANTS IN SPERM QUALITY AND IN VITRO EMBRYO PRODUCTION

Oxidative stress (OS) is the imbalance between the production of Reactive Oxygen Species (ROS) and the protective effect of the responsible antioxidant system for their neutralization and/or removal. OS has been identified as one of the main factors associated with male or female infertility. Indeed, the excessive production of ROS affects the structural and functional integrity of gametes and embryos either in vivo or in vitro. In particular, OS damages proteins, lipids, DNA and accelerates cell apoptosis. These events have been implicated with impaired sperm quality and low fertilization rates. The increased amounts of ROS have also been correlated with poor outcome in assisted reproductive techniques (ART) settings. The biological systems are equipped with antioxidant agents in order to counteract the negative effects of the ROS overproduction. Thus, ROS generation due to pathological conditions of the genital tract or the handling of gametes and embryos at high oxygen tension during ART, render the use of antioxidants essential, to protect the cells from the detrimental consequences of OS. A volume of recent published data indicates that both oral administration and in vitro supplementation of antioxidants are very promising strategies in order to maintain sperm quality characteristics and to ensure fertilization. Nevertheless, further studies should be addressed in order to provide answers on the safety, effectiveness, mechanism of action and combination of different antioxidants, depending on the circumstances. This review summarizes the consensus on the role of oxidative stress and antioxidants in animal and human reproduction. An emphasis is given in the critical role of plant derived antioxidants; this new knowledge may contribute in achievement of high fertilization rates. RESUMENEl estrés oxidativo (OS) es el desbalance entre la producción de Especies Oxigeno Reactivas (ROS) y el efecto protector del sistema antioxidante responsable de su neutralización y/o remoción. EL OS ha sido identificado como uno de los principales factores asociados con la infertilidad masculina y femenina. En realidad, la excesiva producción de ROS afecta la integridad estructural y funcional de gametos y embriones ya sea in vivo o in vitro. En particular, el OS daña proteínas, lípidos, DNA y acelera la apoptosis celular. Estos eventos han sido implicados con disminución de la calidad espermática y bajas tasas de fertilización. Altas cantidades de ROS han sido también correlacionadas con pobres resultados de técnicas de reproducción asistida (ART). Los sistemas biológicos están equipados con agentes antioxidantes con la finalidad de contrarrestar los efectos negativos de la sobreproducción de ROS. Por lo tanto, la generación de ROS debido a condiciones patológicas del tracto genital o por la manipulación de gametos y embriones bajo una alta tensión de oxígeno durante las ART, hace esencial el uso de antioxidantes, para proteger a las células de las consecuencias negativas del OS. Un volumen de información recién publicada indica que tanto la administración oral como la suplementación in vitro de antioxidantes son estrategias muy promisorias para mantener la calidad espermática y mejorar la fertilización. Sin embargo, estudios adicionales deber ser realizados a fin de proveer respuestas sobre la seguridad, efectividad, mecanismo de acción y la combinación de diferentes antioxidantes, según las circunstancias. Esta revisión resume el conceso sobre el rol del estrés oxidativo y los antioxidantes en la reproducción animal y humana. Se ha hecho énfasis en el crítico rol de los antioxidantes derivados de plantas; este nuevo conocimiento puede contribuir al logro de altas tasas de fertilización

Effect of seasonal infertility period on boar sperm proteins and quality characteristics

ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗSwine seasonal infertility reduces the productivity and profitability of a pig farm. The main causes of this condition are elevated environmental temperatures and long photoperiod during the summer season. The aim of this study was to investigate which sperm proteins and parameters are affected during the period of seasonal infertility. Depending on the environmental temperatures, the period from October to June was considered as cold and the period from July to September as warm season. A total of 65 ejaculates from 18 boars were collected over a year. Each semen sample was evaluated for kinetics (Computer Assisted Semen Analyzer), morphology (Sperm Blue stain), viability (Propidium Iodide - Calcein AM stain), mitochondrial membrane potential (Rhodamine 123 – Propidium Iodide stain), membrane integrity and functionality (Hypo-osmotic swelling test) and sperm DNA integrity (Acridine Orange Test). Moreover, selected proteins (HSP90, GPX5, OPN) were detected and quantified. The kinetic parameters VSL, LIN and the midpiece abnormalities were significantly higher in the warm compared to the cold season (p<0.05), while a strong tendency towards higher values for HSP90 and GPX5 was observed in warm compared to cold season (p=0.07and p=0.06, respectively). In conclusion, among the boar sperm characteristics tested in our study, seasonal infertility period negatively affected VSL and LIN kinetics, while GPX5 seminal plasma enzyme and HSP90 sperm surface protein increased their sperm protective effects

Olive oil with high polyphenolic content induces both beneficial and harmful alterations on rat redox status depending on the tissue

Olive oil (OO) possesses a predominant role in the diet of Mediterranean countries. According to a health claim approved by the European Food Safety Authority, OO protects against oxidative stress‑induced lipid peroxidation in human blood, when it contains at least 5 mg of hydroxytyrosol and its derivatives per 20 g. However, studies regarding the effects of a total OO biophenols on redox status in vivo are scarce and either observational and do not provide a holistic picture of their action in tissues. Following a series of in vitro screening tests an OO containing biophenols at 800 mg/kg of OO was administered for 14 days to male Wistar rats at a dose corresponding to 20 g OO/per day to humans. Our results showed that OO reinforced the antioxidant profile of blood, brain, muscle and small intestine, it induced oxidative stress in spleen, pancreas, liver and heart, whereas no distinct effects were observed in lung, colon and kidney. The seemingly negative effects of OO follow the recently formulated idea in toxicology, namely the real life exposure scenario. This study reports that OO, although considered a nutritional source rich in antioxidants, it exerts a tissues specific action when administered in vivo

The effect of dexamethasone on tissue fibrinolytic system in male and female rats

Background: Dexamethasone in low and high doses affects blood fibrinolytic activity both in animals and humans. In this study the effect of a high dose of dexamethasone on plasminogen activator activity (PAA), t-PA antigen level, plasminogen activator inhibition (PAI) and plasmin inhibition (Pl) in rat heal?, brain, liver, lungs and kidneys was investigated in both sexes. Materials and Methods: Twenty male and twenty female adult Wistar rats were used. Dexamethasone was administered as a single intraperitoneal injection (3mg/kg/day) in rats, once daily, for a period of 5 consecutive days. t-PA antigen level was assayed by an enzyme-linked immunoabsorbant assay method PAA, PAI and PI were determined by spectrophotometric methods. The plasminogen used was isolated from I at plasma. Results: Dexamethasone induced variable changes in the fibrinolytic parameters in mt heart, brain and liver of both sexes; in lungs and kidneys dexamethasone had no effect. Conclusion: These changes of PAA, PAI and t-PA antigen level in heart, brain and liver induced by dexamethasone might be of importance regarding the involvement of glucocorticoids and plasminogen activators/plasmin in many pathophysiological conditions

Gossypol-induced inhibition of plasminogen activator activity in human and ovine acrosomal extract

The effect of gossypol-a polycyclic compound isolated from cotton seeds-on the plasminogen activator activity of man and ram acrosomal extracts was explored in vitro. The action of gossypol on the plasminogen activator activity was investigated by a spectrophotometric method using the chromogenic substrate S-2251. Gossypol, a known antispermatogenic agent, was found to effectively inhibit human and ovine acrosomal plasminogen activator activity. The inhibition was dose-dependent. Plasminogen activator activity from man and ram extracts was completely inhibited by 350 mu mol l(-1) and 300 mu mol l(-1) of gossypol, respectively. In additional experiments, low, non-spermicidal concentrations of gossypol (2.5-40 mu mol l(-1)) were found to significantly inhibit plasmin activity in a dose-dependent manner. The results suggest that inhibition of both acrosomal plasminogen activator and plasmin activity is a possible mechanism by which gossypol exerts its antifertility effect, since the plasminogen activator/plasmin system plays a role in the whole process of ovum fertilization