Endogenous and Exogenous Antioxidants As a Tool to Ameliorate Male Infertility Induced by Reactive Oxygen Species

Antioxidants are essential for the maintenance of cellular redox homeodynamics in the male reproductive tract, playing a key role in fertilizing potential. Reactive oxygen species (ROS), at physiological levels, are essential for sperm function and fertilization. Under pathological conditions, abnormal production of ROS may occur. Redox control is primarily regulated by the inner antioxidant system. However, these endogenous antioxidants may be present at abnormal amounts or may be insufficient. Exogenous antioxidants obtained through the diet may have an important role, particularly in specific pathological conditions. This review addresses the regulation of redox homeodynamics in the male reproductive tract by endogenous and exogenous antioxidants and the importance of their cooperation for the maintenance of fertility. Many studies have shown the importance of antioxidants for the preservation of male fertility, mostly under pathological conditions. Excessive antioxidants can inhibit ROS-induced signaling pathways that are essential for the reproductive system. The challenge is to keep the balance between oxidants and antioxidants to maintain ROS-amount at physiological concentration. Although antioxidant therapies are gaining popularity and showing promising results in the improvement of male fertility, there is a lack of knowledge regarding the type of exogenous antioxidant, the doses and time to be administered. It would be of great importance to find a way to restore redox homeostasis under stress conditions. Understanding the poorly studied mechanisms by which exogenous antioxidants cooperate with the inner cellular antioxidant system to counteract free radicals may help in the development of new fertility therapies.