Oxidative Stress, Antioxidant Defenses, and the Liver

Oxidative stress is an unavoidable consequence of life in an oxygenrich atmosphere. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated as by-products of aerobic metabolism and are critical intermediates in the normal physiology and pathophysiology of hepatocytes. To cope with ROS and RNS, cells have developed antioxidant defenses in order to maintain the balance between production and detoxification processes. ROS are important in the creation of oxidative stimuli required for normal physiologic homeostasis of hepatocytes, but when the equilibrium between ROS generation and the antioxidant defense of the cell is disrupted, the consequence is the generation of an oxidative stress condition. In this chapter we will describe the main cellular source of free radicals, the damages generated by ROS accumulation, and all the principal enzymatic and non-enzymatic antioxidant defenses.