title: 1-Methyl-4-phenylpyridinium-like neurotoxicity of a pyridinium metabolite derived from haloperidol: cell culture and neurotransmitter uptake studies.
abstract: It is now generally accepted that the nigrostriatal degenerative properties of the parkinsonian-inducing agent 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine are mediated by the brain monoamine oxidase B generated 1-methyl-4-phenylpyridinium metabolite (MPP+). In this article, the results are described of ongoing efforts to evaluate the MPP(+)-type neurotoxic potential of the haloperidol (HP)-derived pyridinium metabolite HPP+, a 1,4-disubstituted structural analog of MPP+, which is formed in humans and rats treated with HP. Previous studies in the rat have shown that intrastriatal perfusion of HPP+ leads to the irreversible depletion of striatal dopamine and serotonin. Furthermore, HPP+ was a potent inhibitor of NADH-supported mitochondrial respiration. This article reports that HPP+ also is toxic to dopaminergic and serotonergic neurons in cultures of embryonic mesencephalic cells, as measured by loss of the ability of exposed cells to accumulate tritium-labeled dopamine and serotonin and by immunochemical staining techniques. HPP+ also inhibited the uptake of these labeled neurotransmitters by synaptosomes prepared from mouse neostriata (dopamine) and cortical tissues (serotonin). Because HP is unlikely to be a substrate for brain monoamine oxidase B, the production and accumulation of HPP+ in the brain is probably not comparable to that of MPP+. On the other hand, chronic exposure to HP could result in brain levels of this lipophilic quaternary pyridinium species that might coincide with the late-appearing tardive dyskinesias that are observed in some HP-treated patients months and, more often, years after the initiation of HP therapy.
authors.affiliation: Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg.
authors.forename: J
authors.initials: J
authors.lastname: Bloomquist
authors.forename: E
authors.initials: E
authors.lastname: King
authors.forename: A
authors.initials: A
authors.lastname: Wright
authors.forename: C
authors.initials: C
authors.lastname: Mytilineou
authors.forename: K
authors.initials: K
authors.lastname: Kimura
authors.forename: K
authors.initials: K
authors.lastname: Castagnoli
authors.forename: N
authors.initials: N
authors.lastname: Castagnoli
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000633:toxicity*; D000818:Animals; D002478:Cells, Cultured; D004298:Dopamine / Q000378:metabolism; D005260:Female; D006220:Haloperidol / Q000031:analogs & derivatives* / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism
chemical_list: D012701:Serotonin; D006220:Haloperidol; D015655:1-Methyl-4-phenylpyridinium; D004298:Dopamine