Modulation of brain mitochondrial membrane permeability and synaptosomal Ca2+ transport by dopamine oxidation |
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Authors: | Kim Kwang Joon Jang Yoon Yang Hang Eun Sook Lee Chung Soo |
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Institution: | (1) Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, 156-756, Korea |
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Abstract: | Effects of dopamine on the membrane permeability transition, thioredoxin reductase activity, production of free radicals and oxidation of sulfhydryl groups in brain mitochondria and the Ca2+ uptake by Na+-Ca2+ exchange and sulfhydryl oxidation in brain synaptosomes were examined. The brain mitochondrial swelling and the fall of transmembrane potential were altered by pretreatment of dopamine in a dose dependent manner. Depressive effect of dopamine on mitochondrial swelling was reversed by 10 g/ml catalase, and 10 mM DMSO. The activities of thioredoxin reductase in intact or disrupted mitochondria were decreased by dopamine (1-100 M), 25 M Zn2+ and 50 M Mn2+. Dopamine-inhibited enzyme activity was reversed by 10 g/ml SOD and 10 g/ml catalase. Pretreatment of dopamine decreased Ca2+ transport in synaptosomes, which was restored by 10 g/ml SOD and 10 mM DMSO. Dopamine (1-100 M) in the medium containing mitochondria produced superoxide anion and hydrogen peroxide, while its effect on nitrite production was very weak. The oxidation of sulfhydryl groups in mitochondria and synaptosomes were enhanced by dopamine with increasing incubation times. Results suggest that dopamine could modulate membrane permeability in mitochondria and calcium transport at nerve terminals, which may be ascribed to the action of free radicals and the loss of reduced sulfhydryl groups. |
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Keywords: | dopamine brain mitochondria synaptosomes oxidative stress |
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