Reactive Oxygen and Nitrogen Species in Male Reproductive Health: From Molecular Mechanisms to Clinical Consequences

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are critical modulators of male reproductive health, influencing sperm function, hormonal regulation, and overall fertility. While physiological levels of ROS and RNS are essential for processes such as sperm capacitation and acrosome reaction, their overproduction leads to oxidative and nitrosative stress, contributing to male infertility. Excessive ROS and RNS can damage sperm DNA, proteins, and lipids, impairing motility, viability, and fertilizing capacity. Moreover, these reactive species disrupt the hypothalamic-pituitary-gonadal (HPG) axis, leading to hormonal imbalances that further compromise reproductive function. Environmental factors, lifestyle choices, and underlying health conditions exacerbate the production of ROS and RNS, highlighting the need for preventive and therapeutic strategies. Clinically, ROS- and RNS-mediated redox imbalance has been implicated in several male reproductive disorders, including varicocele, genital tract infection and inflammation, obesity, diabetes and other metabolic disorders, and toxicant-related reproductive dysfunction. Antioxidant supplementation has shown promise in mitigating oxidative stress; however, its efficacy varies, and further research is necessary to establish standardized treatment protocols. These findings underscore the clinical relevance of integrating oxidative stress assessment with conventional semen analysis to improve risk stratification and guide targeted interventions in male infertility. This review synthesizes current knowledge on the molecular mechanisms by which ROS and RNS affect male reproduction and discusses potential clinical interventions to address oxidative and nitrosative stress in male infertility.