title: Mitochondrial and metabolic toxicity of 1-methyl-4-(2'-methylphenyl)-1,2,3,6-tetrahydropyridine.
abstract: In previous studies and in the accompanying paper, 1-methyl-4-(2'-methylphenyl)-1,2,3,6-tetrahydropyridine (2'CH3-MPTP) was found to be more potent than MPTP in producing dopaminergic neurotoxicity in mice. One purpose of the present study was to determine whether 1-methyl-4-(2'-methylphenyl)pyridinium (2'CH3-MPP+), the primary oxidation product of 2'CH3-MPTP both in vivo and in vitro, inhibits mitochondrial respiration as does 1-methyl-4-phenylpyridinium (MPP+), the primary oxidation product of MPTP. Another aim was to determine whether treatments which modify MPTP- and 2'CH3-MPTP-induced neurotoxicity in vivo also cause parallel changes in the metabolic toxicity of these compounds. It was found that 2'CH3-MPP+, like MPP+, inhibited the oxidation of NAD(H)-linked substrates by isolated brain mitochondria in a concentration- and time-dependent manner, whereas succinate oxidation was not affected. Thus, the effect was on Complex I in the electron transport chain. Furthermore, 2'CH3-MPP+, like MPP+, enhanced lactate formation by neostriatal tissue slices as would be expected if Complex respiration were inhibited. MPP+ was slightly more potent than 2'CH3-MPP+ in both of these studies. However, 2'CH3-MPTP was several-fold more potent than MPTP in increasing lactate accumulation by the neostriatal slices. This difference in potency correlated with the differing capacities of 2'CH3-MPTP and MPTP to be oxidized by monoamine oxidase (MAO).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine / Q000031:analogs & derivatives; D015655:1-Methyl-4-phenylpyridinium; D000499:Allylamine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000187:drug effects*; D003342:Corpus Striatum / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D011725:Pyridines / Q000378:metabolism / Q000633:toxicity*; D011726:Pyridinium Compounds / Q000633:toxicity
chemical_list: D007773:Lactates; D011725:Pyridines; D011726:Pyridinium Compounds; C048977:1-methyl-4-(2'-methylphenyl)-1,2,3,6-tetrahydropyridine; D019344:Lactic Acid; D000499:Allylamine; C040051:2-(3,4-dimethoxyphenyl)-3-fluoroallylamine; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; D015655:1-Methyl-4-phenylpyridinium