Abstract
Reactive oxygen species (ROS) are produced during normal metabolic reactions in living cells. ROS causes oxidative damage to many types of biomolecules. An age-related increase in oxidative damage to DNA and RNA has been described in the human neurons, which play a vital role in the progression of age-associated neurodegeneration. As dopamine metabolism is believed to be the primary source of ROS, oxidative insults correlate with dopamine levels in the striatum during the progression of neurodegenerative diseases. Parallel changes in dopamine concentrations and vesicular monoamine transporter 2 (VMAT2) binding densities in the striatum were observed. Besides Fenton oxidation taking place, the packing of cytosolic dopamine into synaptic vesicles by VMAT2 inhibits its autoxidation and subsequent decay of dopaminergic neurons. The female bias in the DNA damage in the late-stage Parkinson disease (PD) patients suggests that the sex-determining region of the Y chromosome (SRY) genes are critically involved. ROS are involved in regulating the rate of the aging procession in healthy cohorts and an increased life span of patients with neurodegenerative diseases via stimulation of protective stress responses. Moreover, the DNA repair pathway’s mechanism, as genetic modifiers determine the age at onset through a ROS-inducing mutation.