Oxidative stress and redox regulation of gametogenesis, fertilization, and embryonic development

Abstract

Oxidative stress caused by elevated reactive oxygen species (ROS) is one of the predominant causes of both male and female infertility. Oxidative stress conditions cause either cell death or senescence by oxidation of cellular molecules including nucleic acid, proteins, and lipids. It is particularly important to minimize oxidative stress when in vitro fertilization is performed for the purpose of assisted reproduction. The problems associated with assisted reproductive technology are becoming evident, and it is now the time to clarify its mechanisms and cope with them. On the other hand, the beneficial roles of ROS, such as intracellular signaling, have become evident. The antithetical functions of ROS make it more difficult to overcome the problems caused by oxidative stress. Despite the difficulty in understanding mammalian reproduction, the mechanisms and problems can be gradually unveiled by advanced technology such as genetic modification of animals.

Beta‐mercaptoethanol supplementation of in vitro maturation medium does not influence nuclear and cytoplasmic maturation of equine oocytes

“…Compared to the in vivo environment, in vitro culture conditions entail higher oxygen concentrations, producing an increased level of reactive oxygen species (ROS), with oxidative damage to DNA, lipids, proteins and consequently result in cell growth arrest and cell death of pre‐implantation embryos (Tsunoda, Kimura, & Fujii, ). Glutathione (GSH), a tripeptide thiol (c‐L‐glutamyl‐L‐cysteinylglycine), is the major non‐protein sulphydryl compound in mammalian cells that plays an important role in the maintenance and regulation of the thiol redox status of the cell, thus protecting cell from oxidative damage (Deleuze & Goudet, ).…”

Comparison of different fertilisation media for an in vitro maturation–fertilisation–culture system using flow-cytometrically sorted X chromosome-bearing spermatozoa for bovine embryo production

“…M199 contains antioxidants such as glutathione and L-ascorbic acid, which are missing from the TALP and SOF media formulations (Nedambale et al 2006). Antioxidants are important in mitigating the accumulation of reactive oxygen species (ROS) that can generate oxidative stress and damage normal physiological sperm function (Bansal and Bilaspuri 2010;Aitken et al 2012), impair sperm motility, affect membrane integrity and decrease oocyte penetration capacity (Chatterjee and Gagnon 2001;Bansal and Bilaspuri 2010;Aitken and Henkel 2011;Tsunoda et al 2013). Antioxidants also contribute to the sperm defence mechanism, compromised by the freeze-thawing process, against hydrogen peroxides (Agarwal et al 2006;Bansal and Bilaspuri 2010).…”

Two Spontaneous Pregnancies after Treatment with Ovocyplus<sup>TM</sup> among an Infertile Patient with Two Failed IVF: A Case Report

“…Recent studies have linked the prevalence of female infertility to an increase in oxidative stress (OS) levels, in the various critical micro-or macro-environments in the body [2]- [4]. The OS, a deleterious process that damages cell structures as well as lipids, proteins and DNA, is, by definition, an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense systems [5]. The presence of ROS within the ovary, especially during the ovulation process and the endometrial has significant physiological and pathological implications in the female reproductive tract.…”

“…The presence of ROS within the ovary, especially during the ovulation process and the endometrial has significant physiological and pathological implications in the female reproductive tract. It seems that physiological levels of ROS are required as modulators of a large spectrum of female reproductive pathways such as oocyte maturation, ovarian steroidogenesis, corpus luteum functions, ovulation and are involved in the processes of fertilization, embryo development and pregnancy [5] [6]. Conversely, abnormal increased ROS activity is negatively correlated with oocyte development, embryonic development and pregnancy outcome [5] [7].…”

“…It seems that physiological levels of ROS are required as modulators of a large spectrum of female reproductive pathways such as oocyte maturation, ovarian steroidogenesis, corpus luteum functions, ovulation and are involved in the processes of fertilization, embryo development and pregnancy [5] [6]. Conversely, abnormal increased ROS activity is negatively correlated with oocyte development, embryonic development and pregnancy outcome [5] [7]. Natural enzymatic antioxidants such as catalase, glutathione peroxidase and superoxide dismutase as well as nonenzymatic antioxidants (vitamin A, vitamin E, zinc and selenium) are essential in maintaining adequate levels of ROS in the cell by preventing and removing excess of free radicals [8] [9].…”