title: Melatonin defeats neurally-derived free radicals and reduces the associated neuromorphological and neurobehavioral damage.
abstract: Melatonin and its metabolites are potent antioxidants by virtue of their ability to scavenge both oxygen-based and nitrogen-based radicals and intermediates but also as a consequence of their ability to stimulate the activity of antioxidative enzymes. Melatonin also prevents electron leakage from the mitochondrial electron transport chain thereby diminishing free radical generation; this process is referred to as radical avoidance. The fact that melatonin and its metabolites are all efficient radical scavengers indicates that melatonin is a precursor molecule for a variety of intracellular reducing agents. In specific reference to the brain, melatonin also has an advantage over some other antioxidants given that it readily passes through the blood-brain-barrier. This, coupled with the fact that it and its by-products are particularly efficient detoxifiers of reactive species, make these molecules of major importance in protecting the brain from oxidative/nitrosative abuse. This review summarizes the literature on two brain-related situations, i.e., traumatic brain and spinal cord injury and ischemia/reperfusion, and the neurodegenerative disease, amyotrophic lateral sclerosis, where melatonin has been shown to have efficacy in abating neural damage. These, however, are not the only age-associated neurodegenerative states where melatonin has been found to be protective.
authors.affiliation: Department of Cellular and Structural Biology, The University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA. reiter@uthscsa.edu
authors.forename: R J
authors.initials: RJ
authors.lastname: Reiter
authors.forename: D-X
authors.initials: DX
authors.lastname: Tan
authors.forename: L C
authors.initials: LC
authors.lastname: Manchester
authors.forename: H
authors.initials: H
authors.lastname: Tamura
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism* / Q000502:physiology / Q000627:therapeutic use; D016166:Free Radical Scavengers / Q000378:metabolism* / Q000627:therapeutic use; D005609:Free Radicals / Q000378:metabolism; D016489:Head Injuries, Closed / Q000378:metabolism / Q000517:prevention & control; D006801:Humans; D008550:Melatonin / Q000502:physiology* / Q000627:therapeutic use; D009103:Multiple Sclerosis / Q000378:metabolism / Q000517:prevention & control; D018696:Neuroprotective Agents / Q000627:therapeutic use; D017382:Reactive Oxygen Species / Q000378:metabolism; D015427:Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control; D013124:Spinal Injuries / Q000378:metabolism / Q000517:prevention & control; D020521:Stroke / Q000378:metabolism
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D005609:Free Radicals; D018696:Neuroprotective Agents; D017382:Reactive Oxygen Species; D008550:Melatonin