Generation of ROS in the Male Reproductive System

In contrast to normozoospermic semen samples, teratospermic, oligospermic, and asthenospermic subjects present semen samples with higher concentrations of ROS [39]. These free radicals are produced in spermatozoa by two predominant systems [31, 32, 40, 41]. First, as the generation of ROS is a result of oxygen metabolism, spermatozoal mitochondria are evidently the main contributor of the free radical [36]. Through the act of cellular respiration under normal physiological conditions, superoxide anions are the main ROS produced [36]. Spermatozoa require a constant source of energy to maintain motility and ROS is generated at a mitochondrial level by the nicotinamide adenine dinucleotide-dependant oxido-reductase (NADH) pathway [42].

Second, the sperm plasma membrane can generate ROS through the nicotinamide adenine dinucleotide phosphate-dependant oxidase system (NADPH) [35]. The plasma membrane is incredibly sensitive to ROS due to the high content of polyunsaturated fatty acids (PUFA), primarily docosahexaenoic acid [1, 4, 43]. This form of fatty acid provides fluidity to the plasma membrane with their highly specific lipid composition [36]. However, an unstable high concentration of ROS in an ejaculate can result in the peroxidation of these lipids [44]. The negative resultant effect from the peroxidative damage caused by the oxygen free radicals is increased permeability of the sperm plasma membrane [29, 44-46]. This process is induced by hydrogen peroxide, the most toxic compound for spermatozoa [3, 35, 47]. An additional and third source of ROS in seminal plasma is xanthine oxidase, an enzyme crucial in the catabolism of purine [48].

Pregnancy Guide

Pregnancy Guide

A Beginner's Guide to Healthy Pregnancy. If you suspect, or know, that you are pregnant, we ho pe you have already visited your doctor. Presuming that you have confirmed your suspicions and that this is your first child, or that you wish to take better care of yourself d uring pregnancy than you did during your other pregnancies; you have come to the right place.

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