Autoxidation and MAO-mediated metabolism of dopamine as a potential cause of oxidative stress: role of ferrous and ferric ions

• Published in: Neurochemistry international 2004-07, Vol.45 (1), p.103-116
• Main Authors: Hermida-Ameijeiras, Álvaro, Méndez-Álvarez, Estefanı́a, Sánchez-Iglesias, Sofı́a, Sanmartı́n-Suárez, Carolina, Soto-Otero, Ramón
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Corpus Striatum - drug effects; Corpus Striatum - metabolism; Degenerative and inherited degenerative diseases of the nervous system. Leukodystrophies. Prion diseases; Dopamine - metabolism; Dopamine autoxidation; Ferric Compounds - pharmacology; Ferrous Compounds - pharmacology; Fundamental and applied biological sciences. Psychology; Hydrogen Peroxide - metabolism; Hydroxyl radical; Lipid peroxidation; Male; Medical sciences; Mitochondria - drug effects; Mitochondria - metabolism; Mitochondrial preparations; Monoamine Oxidase - metabolism; Neurology; Oxidants - metabolism; Oxidation-Reduction - drug effects; Oxidative Stress - drug effects; Oxidative Stress - physiology; Parkinson’s disease; Protein oxidation; Rats; Rats, Sprague-Dawley; Thiobarbituric Acid Reactive Substances - metabolism; Vertebrates: nervous system and sense organs
• ISSN: 0197-0186; 1872-9754
• DOI: 10.1016/j.neuint.2003.11.018

The autoxidation and monoamine oxidase (MAO)-mediated metabolism of dopamine (3-hydroxytyramine; DA) cause a continuous production of hydroxyl radical ( OH), which is further enhanced by the presence of iron (ferrous iron, Fe 2+ and ferric ion, Fe 3+). The accumulation of hydrogen peroxide (H 2O 2) in the presence of Fe 2+ appears to discard the involvement of the Fenton reaction in this process. It has been found that the presence of DA significantly reduces the formation of thiobarbituric acid reagent substances (TBARS), which under physiological conditions takes place in mitochondrial preparations. The presence of DA is also able to reduce TBARS formation in mitochondrial preparations even in the presence of iron (Fe 2+ and Fe 3+). However, DA boosted the carbonyl content of mitochondrial proteins, which was further increased in the presence of iron (Fe 2+ and Fe 3+). This latter effect is also accompanied by a significant reduction in thiol content of mitochondrial proteins. It has also been observed how the pre-incubation of mitochondria with pargyline, an acetylenic MAO inhibitor, reduces the production of OH and increases the formation of TBARS. Although, the MAO-mediated metabolism of DA increases MAO-B activity, the presence of iron inhibits both MAO-A and MAO-B activities. Consequently, DA has been shown to be a double-edged sword, because it displays antioxidant properties in relation to both the Fenton reaction and lipid peroxidation and exhibits pro-oxidant properties by causing both generation OH and oxidation of mitochondrial proteins. Evidently, these pro-oxidant properties of DA help explain the long-term side effects derived from l-DOPA treatment of Parkinson’s disease and its exacerbation by the concomitant use of DA metabolism inhibitors.