L-deprenyl confers specific protection against MPTP-induced Parkinson's disease-like movement disorder in the goldfish

Administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to the goldfish causes a reversible, Parkinson's disease-like syndrome which includes loss of noradrenaline and dopamine from the brain, accumulation of the toxic metabolite 1-methyl-4-phenylpyridinium species (MPP⁺), and substantial reduction in movement. L-Deprenyl, a selective monoamine oxidase-B inhibitor, protects the goldfish from loss of movement, but clorgyline, a selective monoamine oxidase-A inhibitor, has no such protective action. L-Deprenyl and clorgyline primarily inhibit goldfish brain monoamine oxidase-B and monoamine oxidase-A, respectively. The mechanism by which MPTP causes reduced movement in goldfish is to cause an increase in resting time. Otherwise normal average velocity occurred during periods of movement. L-Deprenyl protection results in entirely 'normal' levels of resting time and average velocity during times of movement. Equivalent observations regarding l-deprenyl and clorgyline have been made in primate models of MPTP toxicity, and l-deprenyl is used for treatment of Parkinson's disease in humans. Therefore it is suggested that the evolutionarily equivalent subcortical circuity and neural density of the goldfish brain may provide a useful model upon which to search for drugs relevant to human Parkinson's disease.