Hydrogen Peroxide Effect on the Thapsigargin-sensitive Cа2+, Mg2+- ATPase Activity of Sperm Cells

Abstract

Introduction. It is known that mammalian and human spermatozoa are able to generate reactive oxygen species (ROS) which are important regulators of sperm functions (hyperactivation, capacitation and acrosome reaction). However, an excessive ROS generation appears to be related to male infertility. An uncontrolled production of ROS or impaired antioxidant defense enzyme and non-enzyme mechanisms leads to oxidative stress which is harmful to sperm cells. It has been demonstrated recently that oxidative stress is implicated in male infertility. ROS-mediated damage to sperm is a considerable pathology contribution in 30% to 80% of unselected infertile patients [1, 2]. One of the most common ROS having potential implications in the reproductive biology is hydrogen peroxide (H2O2). It was shown that human spermatozoa incubated and exposed to artificial H2O2 has detrimental effects on sperm motility and give rise to a significant increase in the overall ROS [4]. Oxidative stress may have negative impact on the activity of membranebound enzymes such as Са2+, Мg2+-АТPase which is involved in maintaining calcium homeostasis in spermatozoa. Ion-transporting ATPases are very sensitive to oxidation. The inhibition of Са2+, Мg2+-АТPase may occur through a different mechanism [9, 12]. The aim of the present work was to evaluate the H2O2 effect on the main kinetic parameters of ATP hydrolysis by thapsigargin-sensitive Са2+, Мg2+-АТPase of spermatozoa of fertile (normozoospermia) and infertilite men (asthenozoospermia). Material and Methods. Patients. 10 infertile men with asthenozoospermia were involved in this study. The main exclusion criteria: men who were currently on any medication or antioxidant supplementation were not included. In addition, men with infertility over 10 years, azoospermia, genital infection, chronic illness and serious systemic diseases, smokers and alcoholic men were excluded from the study because of their well-known high seminal ROS levels and decreased antioxidant activity which may affect ATPase activities. Infertile men were age-matched to fertile control cases. The control group consisted of 8 healthy men with somatic fertility, normozoospermia and confirmed parenthood (married for 3–10 years and have 1–3 healthy children). Semen samples were obtained by masturbation and collected into sterile containers, following 3–5 days of abstinence from sexual activity. After liquefaction at 37 °C with 5 % CO2 in air, semen samples were examined for volume, sperm concentration, pH, morphology and motility according to World Health Organization guidelines (WHO, 2010) [11]. Before turning to study, all men were aware of patient information leaflets and gave informed consent to participate in the research. Terms of sample selection meet the requirements of