The effect of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on striatal and limbic catecholamine neurones in white and black mice. Antagonism by monoamine oxidase inhibitors.

Albino mice and pigmented mice were treated for 6 days with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) at the maximum tolerated doses (2 days at 30 mg/kg i.p., 2 days at 40 mg/kg i.p. and 2 days at 50 mg/kg i.p. in white mice, 6 days at 30 mg/kg i.p. in pigmented mice) and the effects of simultaneous treatment with the monoamine oxidase inhibitors, deprenyl (1 mg/kg, i.p.), MDL 72145 (0.5 mg/kg, i.p.) and clorgyline (5 mg/kg, i.p.), determined behaviourally (daily for 6 days and for 4 days after withdrawal) and biochemically (92 hr after withdrawal of drug). In albino mice MPTP caused depletions of dopamine (90%), dihydroxyphenylacetic acid (DOPAC; 82%) and homovanillic acid (HVA; 65%) in the striatum and in dopamine (54%), DOPAC (51%) and HVA (53%) in the nigra. However, MPTP was not selective in its action since the levels of dopamine and its metabolites were also reduced in limbic tissue. Further, MPTP affected the function of noradrenaline, with reduced levels in tissues of the striatum (74%) and nigra (46%). Pigmented mice were as susceptible as albino mice to the actions of MPTP to reduce the levels of dopamine and metabolites in the striatum. However, the limbic areas and substantia nigra of the pigmented mouse were more resistant to the actions of MPTP. Treatment with deprenyl and MDL 72145 (but not clorgyline) could be shown to reduce the biochemical and behavioural consequences of the action of MPTP (although behavioural changes, development of severe motor incapacitation and prostrate appearance, appeared to be non-specific).(ABSTRACT TRUNCATED AT 250 WORDS)