Molecular basis of discrepancies in neurotoxic properties among 1-methyl-4-aryl-1,2,3,6-tetrahydropyridines

Autor: Ludmila G. Dubova, Nadegda N. Lermontova, Sergey O. Bachurin, Sergey E. Tkachenko, L. S. Solyakov, Sergey O. Sablin
Rok vydání: 1992
Předmět:
Zdroj: Molecular and Chemical Neuropathology. 17:189-200
ISSN: 1044-7393
DOI: 10.1007/bf03160009
Popis: The relationship between structural specificity of the main stages of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) action and the display of parkinsonogenic properties among homologous structures in a number of 4-tolyl derivatives of MPTP has been studied. All the compounds are better substrates for monoamine oxidase (MAO) than MPTP. MAO is inactivated during the reaction according to a mechanism of irreversible inhibition by 2,3-dihydropyridinium metabolite. All the tolyl derivatives are stronger inhibitors of MAO than 1-methyl-2,3-dihydropyridinium (MPDP). A significant contribution of enzyme inhibition to the catalytic conversion of the substrate leads to the fact that substrates having equal (para isomer) or even higher (meta isomer) values of catalytic parameters are oxidized by MAO to a lesser extent than MPTP. It has been found that all 4-arylpyridiniums (final products of MATP bioconversion) competitively and reversibly inhibit [14C]dopamine (DA) uptake in mouse brain synaptosomes. Affinity toward DA transporter characterized by KI (microM) is 0.37 +/- 0.04, 0.7 +/- 0.1, 2.0 +/- 0.15, 2.0 +/- 0.35 for MPP, and its o-, m-, and p-tolyl derivatives, respectively. Joint calculation of specificity factors for the processes discussed define the following rank order for the bio-delivery of MATP's metabolic produces into DA nerve terminals: o-tolylMPTPm-tolylp-tolyl. The regularity revealed is in good agreement with the observed relative potency of these compounds to cause dopaminergic neurodegeneration.
Databáze: OpenAIRE