title: Neurotoxic mechanisms of 2,9-dimethyl-beta-carbolinium ion in primary dopaminergic culture.
abstract: beta-Carbolines are potential endogenous and exogenous neurotoxicants that may contribute to the pathogenesis of Parkinson's disease. The 2,9-dimethyl-beta-carbolinium ion (either 2,9-dimethyl-beta-norharmanium or 2,9-Me(2)NH(+)) was found to be neurotoxic in primary mesencephalic cultures and to be a potent inhibitor of mitochondrial complex I. However, the precise mechanisms of cell death remained obscure. Here, we investigated the mechanism of cell death in primary dopaminergic cultures of the mouse mesencephalon mediated by 2,9-Me(2)NH(+). The beta-carboline caused preferential death of dopaminergic neurones, which could not be attributed to cellular uptake via the dopamine transporter. Transient incubation with 2,9-Me(2)NH(+) for 48 h caused a progressive deterioration in the morphology of dopaminergic neurones during a 5-day recovery period and persistent damage to the overall culture. An increase in free radical production and caspase-3 activity, as well as a decrease of respiratory activity, mitochondrial membrane potential and ATP content, contributed to toxicity and pointed to an apoptotic mode of cell death, although a significant quantity of cells dying via necrosis were present simultaneously. These data underline the preferential susceptibility of dopaminergic neurones to 2,9-Me(2)NH(+) as a potent, oxidative stress generating neurotoxin.
authors.affiliation: Department of Neurology, Technical University of Dresden, Dresden, Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Hamann
authors.forename: Hans
authors.initials: H
authors.lastname: Rommelspacher
authors.forename: Alexander
authors.initials: A
authors.lastname: Storch
authors.forename: Heinz
authors.initials: H
authors.lastname: Reichmann
authors.forename: Gabriele
authors.initials: G
authors.lastname: Gille
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002243:Carbolines / Q000378:metabolism / Q000633:toxicity*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D002478:Cells, Cultured; D004298:Dopamine / Q000502:physiology*; D005260:Female; D007091:Image Processing, Computer-Assisted; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D008928:Mitochondria / Q000187:drug effects; D009336:Necrosis; D009419:Nerve Tissue Proteins / Q000032:analysis / Q000096:biosynthesis; D009474:Neurons / Q000187:drug effects / Q000473:pathology / Q000502:physiology*; D020258:Neurotoxicity Syndromes / Q000473:pathology*; D009569:Nitric Oxide / Q000378:metabolism; D010879:Piperazines / Q000494:pharmacology; D011247:Pregnancy; D011726:Pyridinium Compounds / Q000633:toxicity; D017382:Reactive Oxygen Species / Q000378:metabolism; D013378:Substantia Nigra / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D002243:Carbolines; D009419:Nerve Tissue Proteins; D010879:Piperazines; D011726:Pyridinium Compounds; D017382:Reactive Oxygen Species; D009569:Nitric Oxide; D019344:Lactic Acid; C005986:2,9-dimethyl-beta-carbolinium; C026560:1-(4-methoxyphenyl)pyridinium; D000255:Adenosine Triphosphate; C043425:vanoxerine; D007770:L-Lactate Dehydrogenase; D014446:Tyrosine 3-Monooxygenase; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D004298:Dopamine