Extracellular toxicity of 6-hydroxydopamine on PC12 cells.

6-hydroxydopamine (6-OHDA) is usually thought to cross cell membrane through dopamine uptake transporters, to inhibit mitochondrial respiration and to generate intracellular reactive oxygen species. In this study, we show that the anti-oxidants catalase, glutathione and N-acetyl-cysteine are able to reverse the toxic effects of 6-OHDA. These two latter compounds considerably slow down 6-OHDA oxidation in a cell free system suggesting a direct chemical interaction with the neurotoxin. Moreover, desipramine does not protect PC12 cells and 6-OHDA is also strongly toxic towards non-catecholaminergic C6 and NIH3T3 cells. These results thus suggest that 6-OHDA toxicity on PC12 cells mainly involves an extracellular process.