Actions and mechanisms of reactive oxygen species and antioxidative system in semen

Abstract

Oxidative stress caused by the production of reactive oxygen species (ROS) in excess of the defense capability of the body’s antioxidative system is one of the primary reasons of sperm dysfunction. ROS, including free radicals, oxygen ions, and peroxides, are by-products of normal cellular metabolism. These molecules are important in physiological processes and cellular signaling pathways. Moderate amounts of ROS are indispensable for sperm physiology, such as capacitation, hyperactivation, and sperm-egg fusion. However, relatively high level of ROS can disrupt the integrity of sperm DNA and limit the fertilizing potential because of the compromised lipids and proteins in the sperm membrane. The antioxidative system of semen is composed of enzymatic and non-enzymatic antioxidants which interact with each other to maintain an intricate balance between ROS production and scavenging system. This review highlights the mechanisms of ROS production and elimination as well as the physiological and pathological effects on spermatozoa.