Effect of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in goldfish brain.

The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which selectively damages dopaminergic neurons in mammals, caused a marked depletion of tyrosine hydroxylase (TH) immunoreactivity in the goldfish brain. The concomitant ultrastructural observations showed the neurotoxic effect of MPTP on telencephalic, diencephalic and medullar neurons. The affected neurons revealed darkening of the cytoplasm and swelling of the mitochondria and the endoplasmic reticulum. Concomitant significant decreases in dopamine (DA) and noradrenaline (NA) levels were determined in the brain areas where morphological observations were performed. The loss of catecholamine levels was completely prevented by the treatment with the monoamine oxidase (MAO) inhibitor pargyline to prevent MPTP oxidation. The results indicate that in goldfish brain, acute MPTP administration causes selective catecholamine depletion, without altering the serotoninergic system.