An Update on Oxidative Damage to Spermatozoa and Oocytes

Abstract

On the one hand, reactive oxygen species (ROS) are mandatory mediators for essential cellular functions including the function of germ cells (oocytes and spermatozoa) and thereby the fertilization process. However, the exposure of these cells to excessive levels of oxidative stress by too high levels of ROS or too low levels of antioxidative protection will render these cells dysfunctional thereby failing the fertilization process and causing couples to be infertile. Numerous causes are responsible for the delicate bodily redox system being out of balance and causing disease and infertility. Many of these causes are modifiable such as lifestyle factors like obesity, poor nutrition, heat stress, smoking, or alcohol abuse. Possible correctable measures include foremost lifestyle changes, but also supplementation with antioxidants to scavenge excessive ROS. However, this should only be done after careful examination of the patient and establishment of the individual bodily antioxidant needs. In addition, other corrective measures include sperm separation for assisted reproductive techniques. However, these techniques have to be carried out very carefully as they, if applied wrongly, bear risks of generating ROS damaging the germ cells and preventing fertilization.

Conservative Nonhormonal Options for the Treatment of Male Infertility: Antibiotics, Anti-Inflammatory Drugs, and Antioxidants

“…The seminal plasma contains natural antioxidant, such as vitamins C and E, superoxide dismutase (SOD), glutathione, uric acid, and the polyamine spermine that acts as a free radical scavenger [21]. However, the high concentration of unsaturated lipids in the plasma membrane and the relative paucity of oxyradical scavenger enzyme (due to the virtual absence of cytoplasma) make mature spermatozoa particularly susceptible to oxidative stress.…”

“…The polyunsaturated fatty acids of sperm plasma membrane are a target of ROS action leading to lipid peroxidation, measurable as malondialdehyde (MDA) in the seminal plasma, and loss of sperm motility [21]. ROS can also alter biofunctional sperm parameters, resulting in a greater number of spermatozoa with fragmented DNA that seems to be inversely correlated with sperm count, morphology, motility, and fertilization rate [21, 22].…”

“…ROS can also alter biofunctional sperm parameters, resulting in a greater number of spermatozoa with fragmented DNA that seems to be inversely correlated with sperm count, morphology, motility, and fertilization rate [21, 22]. ROS overproduction causes also a greater frequency of single- and double-strand DNA breaks and increased DNA protein cross-linking [8].…”

“…ROS overproduction causes also a greater frequency of single- and double-strand DNA breaks and increased DNA protein cross-linking [8]. Furthermore, ROS have the ability to damage mitochondrial DNA [21]. …”

Application of dietetics in reproductive medicine

“…However, while explaining pathophysiology of fertility disorders in obese women, a relatively smaller importance is ascribed to other mechanisms, among which is mentioned the role of the environment of the maturation of the ovum, which exerts a direct effect on the quality of the oocyte, quality of the embryo, and the chance to obtain pregnancy. Fatty tissue collected in the body contributes to an increase in the phenomenon of oxidative stress by production of an excess of adipocytokines and reactive oxygen species, which in the follicular fluid negatively affect the maturating oocyte [21,22,23]. Also, mitochondrial dysfunction related with obesity contributes to the occurrence of oxygen shock [24].…”