Abstract
Many researchers have been studying the association of monoamine neurotransmitters and their metabolites with brain cell damage after transient cerebral ischemia or in Parkinson's disease. In the present study, we investigated in vitro the antioxidant effect involved in dopamine (DA) metabolism on irondependent and iron-independent lipid peroxidation using frozen striatal tissue, whole brain homogenate and its mitochondrial fraction from rats. Using 7-week-old male Wistar rats, we studied lipid peroxide formation in striatal samples, homogenate and mitochondrial fractions in the presence of various high concentrations of DA. Addition of DA (10-4 M) to reaction mixtures apparently suppressed lipid peroxidation, as determined with thiobarbituric acid methods, by about 30% to 40% of control. Pargyline, a monoamine oxidase inhibitor, antagonized the decrease in lipid peroxidation in the homogenate and enhanced the effect of DA in the mitochondrial fraction in the presence of iron ion. These effects seem to derive not only from the anti-oxidative effects of DA and their metabolites but also from the process of DA metabolism by monoamine oxidase as a whole.
