Oxidative Stress in Exercising Horses : Fact or Fiction ?

WHAT IS OXIDATIVE STRESS?
Oxidative stress is defined as an imbalance between the endogenous antioxidant defence of the organism and the exogenous or endogenous pro-oxidant burden in favour of pro-oxidants. Pro-oxidants are highly reactive molecules able to induce cellular damage by oxidation of cellular components, such as lipids, proteins, nucleic acids and carbohydrates. These “reactive oxygen species” (ROS) are generated by three physiologic processes: (1)Leukocytes release important amounts of ROS during inflammation (respiratory burst). (2)Incomplete oxygen reduction by mitochondria leads to formation and release of ROS. (3)Several enzymes generate ROS as by-products of metabolic processes. Antioxidants, such as vitamin A, C and E, glutathione, flavonoids, uric acid etc., are able to transform or inactivate ROS into less reactive molecules. Antioxidants are therefore essential to prevent cellular damage by pro-oxidants. [...]