Inhibition of Glutamate Transport in Synaptosomes by Dopamine Oxidation and Reactive Oxygen Species
Article first published online: 18 NOV 2002
Journal of Neurochemistry
Volume 69, Issue 3, pages 1185–1195, September 1997
How to Cite
Berman, S. B. and Hastings, T. G. (1997), Inhibition of Glutamate Transport in Synaptosomes by Dopamine Oxidation and Reactive Oxygen Species. Journal of Neurochemistry, 69: 1185–1195. doi: 10.1046/j.1471-4159.1997.69031185.x
- Issue published online: 18 NOV 2002
- Article first published online: 18 NOV 2002
- Received October 1, 1996; final revised manuscript received April 18, 1997; accepted April 22, 1997.
- Glutamate uptake;
- Free radicals;
- Oxidative stress
Abstract: Dopamine can form reactive oxygen species and other reactive metabolites that can modify proteins and other cellular constituents. In this study, we tested the effect of dopamine oxidation products, other generators of reactive oxygen species, and a sulfhydryl modifier on the function of glutamate transporter proteins. We also compared any effects with those on the dopamine transporter, a protein whose function we had previously shown to be inhibited by dopamine oxidation. Preincubation with the generators of reactive oxygen species, ascorbate (0.85 mM) or xanthine (500 µM) plus xanthine oxidase (25 mU/ml), inhibited the uptake of [3H]glutamate (10 µM) into rat striatal synaptosomes (−54 and −74%, respectively). The sulfhydryl-modifying agent N-ethylmaleimide (50–500 µM) also led to a dose-dependent inhibition of [3H]glutamate uptake. Preincubation with dopamine (100 µM) under oxidizing conditions inhibited [3H]glutamate uptake by 25%. Exposure of synaptosomes to increasing amounts of dopamine quinone by enzymatically oxidizing dopamine with tyrosinase (2–50 U/ml) further inhibited [3H]glutamate uptake, an effect prevented by the addition of glutathione. The effects of free radical generators and dopamine oxidation on [3H]glutamate uptake were similar to the effects on [3H]dopamine uptake (250 nM). Our findings suggest that reactive oxygen species and dopamine oxidation products can modify glutamate transport function, which may have implications for neurodegenerative processes such as ischemia, methamphetamine-induced toxicity, and Parkinson's disease.