The neurochemical and clinical effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in small animals.

The recent discovery that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes a syndrome of Parkinsonism in man and monkey has stimulated the search for a small animal model of Parkinsonism. In this study, MPTP was administered to a series of small animals and observations made on clinical and neurochemical changes. The clinical effects of MPTP in rabbits, guinea pigs, and rats were short lived, and no chronic Parkinsonian syndrome developed. The C57 black mouse, however, although also not showing clinical changes, proved to be an ideal neurochemical model in which to study the effects of MPTP since striatal dopamine levels were reliably reduced to 13% of control values after 4 intraperitoneal injections of 30 mg/kg MPTP. Pathological study of the striatum and substantia nigra in the mouse model failed to show any alteration in neuronal morphology or numbers. Although the effect of MPTP on striatal dopamine lasted for up to 2 weeks after the last MPTP injection, the possibility exists that no neurotoxic effects occur and the observed dopamine depletion is pharmacological only.