The Role of Oxidative Stress in Neurodegenerative Diseases

Abstract

Oxidative stress is induced by an imbalanced redox states, involving either excessive generation of reactive oxygen species (ROS) or dysfunction of the antioxidant system. The brain is one of organs especially vulnerable to the effects of ROS because of its high oxygen demand and its abundance of peroxidation-susceptible lipid cells. Previous studies have demonstrated that oxidative stress plays a central role in a common pathophysiology of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Antioxidant therapy has been suggested for the prevention and treatment of neurodegenerative diseases, although the results with regard to their efficacy of treating neurodegenerative disease have been inconsistent. In this review, we will discuss the role of oxidative stress in the pathophysiology of neurodegenerative diseases and in vivo measurement of an index of damage by oxidative stress. Moreover, the present knowledge on antioxidant in the treatment of neurodegenerative diseases and future directions will be outlined.

Keywords: Alzheimer's disease; Antioxidant; Neurodegenerative disease; Oxidative stress; Parkinson's disease; Reactive oxygen species.

Fig. 1. Common reactive oxygen species (ROS). The consecutive reduction of oxygen through adding electrons cause the formation of a variety of ROS, which include superoxide (O₂^-), hydroxyl radical (·OH), hydroxyl ion (OH^-) and hydrogen peroxide (H₂O₂). The red dot indicates an unpaired electron.

Fig. 2. Generation of ROS. The superoxide (O₂^-) is generated from O₂as a by-product of respiratory chain complex in the mitochondria or by NADPH oxidase. By superoxide dismutase (SOD), the superoxide (O₂^-) can be transformed into hydrogen peroxide (H₂O₂), which can be further transformed to a number of other ROS such as hydroxyl radicals (·OH) and hydroxyl anions (OH^-).