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[Metabolic activation of azaheterocyclics induced dopaminergic toxicity: possible candidate neurotoxins underlying idiopathic Parkinson's disease].
Nihon Hoigaku Zasshi. 1998 Oct; 52(5):301-5.NH

Abstract

In 1983, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a contaminant of "synthetic heroin", has been reported to induce parkinsonian symptoms in humans, who were responsive to L-DOPA therapy, as a result of the degeneration of nigrostriatal neurons. The "MPTP story" hypothesizes that Parkinson's disease may be initiated or percipitated by environmental and/or endogenous toxins by a mechanism similar to that of MPTP in genetically-predisposed individuals. Several classes of heterocyclic molecules structurally related to MPTP have been advanced as possible neurotoxicant precursors underlying the nigrostriatal degeneration in Parkinson's disease. Indoleamine-related beta-carbolines (beta Cs), a class of heterocyclics which are basically plant alkaloids, are proposed as the most promising natural MPTP-like toxicants or protoxicants. In this article, beta Cs and N-methylated beta C cations are reviewed with regards to their formation, bioactivation, toxicity and presence in the human central nervous system. The enzymes in mammalian brain particulate fractions methylate beta Cs, sequentially forming 2-mono-[N]-methylated (2-Me beta C+s) and neurotoxic 2,9-di-[N, N']-methylated (2,9-Me2 beta C+s) beta-carbolinium cations. These beta C+s are structural analogs of 1-methyl-4-phenylpyridinium ion (MPP+), an active metabolite of MPTP, with a nitrogen bridge. The beta C+s not only inhibit DA reuptake and tyrosine hydroxylase, but also function as NADH-linked respiratory inhibitors in isolated mitochondria. The quarternization of beta C strikingly increased the affinity for dopamine transporter with 2-10 times greater Km and 10 times smaller Vmax values than MPP+. Furthermore, we have found higher concentrations of beta C+s localized in the nigra than in the cortex, and observed the S-adenosyl-L-methionine-dependent methylation of 2[beta]- and 9[indole]-nitrogens of beta Cs in non-parkinsonian human brains. Moreover, the cerebrospinal fluid levels of these beta C+s are higher in parkinsonian than non-parkinsonian patients. Simple beta-carboline induced parkinsonian-like symptoms in mice via N-methylation. These results indicated that beta C is a selective dopaminergic toxin precursor, that is sequentially methylated to form 2,9-Me2 beta C+ that could be an underlying factor in idiopathic Parkinson's disease.

Authors+Show Affiliations

Matsubara K
Department of Hospital Pharmacy & Pharmacology, Asahikawa Medical College, Japan.

MeSH

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridineAnimalsBrainCarbolinesDisease Models, AnimalDopamineHumansMPTP PoisoningMiceParkinson Disease

Pub Type(s)

English Abstract
Journal Article
Review

Language

jpn

PubMed ID

10077975

Citation

Matsubara, K. "[Metabolic Activation of Azaheterocyclics Induced Dopaminergic Toxicity: Possible Candidate Neurotoxins Underlying Idiopathic Parkinson's Disease]." Nihon Hoigaku Zasshi = the Japanese Journal of Legal Medicine, vol. 52, no. 5, 1998, pp. 301-5.
Matsubara K. [Metabolic activation of azaheterocyclics induced dopaminergic toxicity: possible candidate neurotoxins underlying idiopathic Parkinson's disease]. Nihon Hoigaku Zasshi. 1998;52(5):301-5.
Matsubara, K. (1998). [Metabolic activation of azaheterocyclics induced dopaminergic toxicity: possible candidate neurotoxins underlying idiopathic Parkinson's disease]. Nihon Hoigaku Zasshi = the Japanese Journal of Legal Medicine, 52(5), 301-5.
Matsubara K. [Metabolic Activation of Azaheterocyclics Induced Dopaminergic Toxicity: Possible Candidate Neurotoxins Underlying Idiopathic Parkinson's Disease]. Nihon Hoigaku Zasshi. 1998;52(5):301-5. PubMed PMID: 10077975.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - [Metabolic activation of azaheterocyclics induced dopaminergic toxicity: possible candidate neurotoxins underlying idiopathic Parkinson's disease]. A1 - Matsubara,K, PY - 1999/3/17/pubmed PY - 1999/3/17/medline PY - 1999/3/17/entrez SP - 301 EP - 5 JF - Nihon hoigaku zasshi = The Japanese journal of legal medicine JO - Nihon Hoigaku Zasshi VL - 52 IS - 5 N2 - In 1983, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a contaminant of "synthetic heroin", has been reported to induce parkinsonian symptoms in humans, who were responsive to L-DOPA therapy, as a result of the degeneration of nigrostriatal neurons. The "MPTP story" hypothesizes that Parkinson's disease may be initiated or percipitated by environmental and/or endogenous toxins by a mechanism similar to that of MPTP in genetically-predisposed individuals. Several classes of heterocyclic molecules structurally related to MPTP have been advanced as possible neurotoxicant precursors underlying the nigrostriatal degeneration in Parkinson's disease. Indoleamine-related beta-carbolines (beta Cs), a class of heterocyclics which are basically plant alkaloids, are proposed as the most promising natural MPTP-like toxicants or protoxicants. In this article, beta Cs and N-methylated beta C cations are reviewed with regards to their formation, bioactivation, toxicity and presence in the human central nervous system. The enzymes in mammalian brain particulate fractions methylate beta Cs, sequentially forming 2-mono-[N]-methylated (2-Me beta C+s) and neurotoxic 2,9-di-[N, N']-methylated (2,9-Me2 beta C+s) beta-carbolinium cations. These beta C+s are structural analogs of 1-methyl-4-phenylpyridinium ion (MPP+), an active metabolite of MPTP, with a nitrogen bridge. The beta C+s not only inhibit DA reuptake and tyrosine hydroxylase, but also function as NADH-linked respiratory inhibitors in isolated mitochondria. The quarternization of beta C strikingly increased the affinity for dopamine transporter with 2-10 times greater Km and 10 times smaller Vmax values than MPP+. Furthermore, we have found higher concentrations of beta C+s localized in the nigra than in the cortex, and observed the S-adenosyl-L-methionine-dependent methylation of 2[beta]- and 9[indole]-nitrogens of beta Cs in non-parkinsonian human brains. Moreover, the cerebrospinal fluid levels of these beta C+s are higher in parkinsonian than non-parkinsonian patients. Simple beta-carboline induced parkinsonian-like symptoms in mice via N-methylation. These results indicated that beta C is a selective dopaminergic toxin precursor, that is sequentially methylated to form 2,9-Me2 beta C+ that could be an underlying factor in idiopathic Parkinson's disease. SN - 0047-1887 UR - https://www.unboundmedicine.com/medline/citation/10077975/[Metabolic_activation_of_azaheterocyclics_induced_dopaminergic_toxicity:_possible_candidate_neurotoxins_underlying_idiopathic_Parkinson's_disease]_ L2 - https://www.diseaseinfosearch.org/result/5603 DB - PRIME DP - Unbound Medicine ER -