Journal of Neuroscience, Vol 15, 5912-5918, Copyright © 1995 by Society for Neuroscience
A selective toxicity toward cultured mesencephalic dopaminergic neurons is induced by the synergistic effects of energetic metabolism impairment and NMDA receptor activation
I Marey-Semper, M Gelman and M Levi-Strauss
INSERM U 114, College de France, Paris.
Numerous observations strongly support the hypothesis that dopaminergic
neurons could be particularly vulnerable to an impairment of their
energetic metabolism. In order to demonstrate the existence of such a
selective vulnerability, the toxic effects of rotenone, an inhibitor of
complex I of the respiratory chain, and of glutamate, which is very likely
involved in the neurotoxicity induced by an energetic stress, were analyzed
on cultured mouse mesencephalic neurons. Toxicity toward dopaminergic and
GABAergic neurons was compared by measuring the residual uptakes of
dopamine and GABA. Exposure to 5 nM rotenone for 6 hr or to a low
concentration of glutamate (100 microM) for 1 hr did not lead to a high
selective toxic effect on dopaminergic neurons. In contrast, dopaminergic
neurons were three times less resistant to the sequential exposure to
rotenone and glutamate than GABAergic neurons. A particular resistance of
mesencephalic GABAergic neurons to the synergistic toxic effects of
rotenone and glutamate was ruled out since two other neuronal types, the
striatal cholinergic and GABAergic neurons, displayed the same weak
vulnerability as the mesencephalic GABAergic neurons. This selective toxic
effect of glutamate on rotenone- pretreated dopaminergic neurons was
blocked by either AMPA or NMDA receptor antagonists and mimicked by
combined treatment with AMPA and NMDA, or by NMDA alone when the medium was
deprived of Mg2+ ions. Moreover, this NMDA-selective neurotoxicity was
critically dependent on the presence of a physiological extracellular
sodium concentration, since the use of choline chloride instead of sodium
chloride had a protective effect on dopaminergic neurons.(ABSTRACT
TRUNCATED AT 250 WORDS)