Neurotoxic effect of 1-methyl-4-phenylpyridinium ion on dopaminergic neurons of the retina of goldfish.

Dopaminergic neurons of the goldfish retina were selectively destroyed after a single intravitreal injection of 1-methyl-4-phenylpyridinium ion (MPP+). The ultrastructural analysis of the retina 3 days after toxin administration shows darkening of some retinal neurons present in the inner nuclear layer including their cytoplasmic processes. Both uptake and release of dopamine were reduced in the toxin-injected retina, whereas choline acetyltransferase (ChAT) and glutamic acid decarboxylase (GAD) activities, as well as the uptake of D-[3H]aspartate were not affected.