The ex vivo effect of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on rat intra- and extraneuronal monoamine oxidase activity.
After i.p. injection of 30 mg/kg 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) daily for 4 days and sacrificing the rats 4 h after the last injection, striatal monoamine oxidase (MAO)-A and -B activities, assayed by conventional method with 5-hydroxytryptamine (5-HT) and benzylamine, were not changed. By an uptake technique, with dopamine as the substrate for both uptake and MAO, intrasynaptosomal MAO-A and -B activities were found to be greatly reduced with a greater MAO-A reduction. Intrasynaptosomal 5-HT oxidation by MAO-A was not changed in other forebrain regions treated with these MPTP doses. Similar results were also found with two brain preparations treated with single MPTP doses (30 mg/kg). This reduction in intrasynaptosomal MAO activity was completely absent after treatment with lower MPTP doses (15 mg/kg, daily for 5 days) and 5 days of a withdrawal period. The decrease in MAO activity might have been due to the decrease in DA transport into striatal synaptosomes during the enzyme assay and/or to reversible inhibition of intrasynaptosomal MAO by MPP+.
D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects*; D004027:Diencephalon / Q000187:drug effects; D004298:Dopamine / Q000378:metabolism; D005110:Extracellular Space / Q000201:enzymology; D008297:Male; D008995:Monoamine Oxidase / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism; D013574:Synaptosomes / Q000201:enzymology; D013687:Telencephalon / Q000187:drug effects
D011725:Pyridines; D012701:Serotonin; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D008995:Monoamine Oxidase; D004298:Dopamine