title: Ca(2+) and Na(+) dependence of 3-hydroxyglutarate-induced excitotoxicity in primary neuronal cultures from chick embryo telencephalons.
abstract: Glutaryl-CoA dehydrogenase deficiency (also known as glutaric aciduria type I) is an autosomal, recessively inherited neurometabolic disorder with a distinct neuropathology characterized by acute encephalopathy during a vulnerable period of brain development. Neuronal damage in this disease was demonstrated to involve N-methyl-D-aspartate (NMDA) receptor-mediated neurotoxicity of the endogenously accumulating metabolite 3-hydroxyglutarate (3-OH-GA). However, it remained unclear whether NMDA receptors are directly or indirectly activated and whether 3-OH-GA disturbs the intracellular Ca(2+) homeostasis. Here we report that 3-OH-GA activated recombinant NMDA receptors (e.g. NR1/NR2A) but not recombinant alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptors (e.g. GluR-A/GluR-B) in HEK293 cells. Fluorescence microscopy using fura-2 as Ca(2+) indicator revealed that 3-OH-GA increased intracellular Ca(2+) concentrations in the presence of extracellular Ca(2+) in cultured chick neurons. Similar to glutamate-induced cell damage, 3-OH-GA neurotoxicity was modulated by extracellular Na(+). The large cation N-methyl-D-glucamine, which does not permeate NMDA receptor channels, enhanced 3-OH-GA-induced Ca(2+) increase and cell damage. In contrast, 3-OH-GA-induced neurotoxicity was reduced after replacement of Na(+) by Li(+), which permeates NMDA channels but does not affect the Na(+)/Ca(2+) exchanger in the plasma membrane. Spectrophotometric analysis of respiratory chain complexes I-V in submitochondrial particles from bovine heart revealed only a weak inhibition of 3-OH-GA on complex V at the highest concentration tested (10 mM). In conclusion, the present study revealed that NMDA receptor activation and subsequent disturbance of Ca(2+) homeostasis contribute to 3-OH-GA-induced cell damage.
authors.affiliation: Division of Metabolic and Endocrine Diseases, University Children's Hospital, Heidelberg, Germany. Stefan_Koelker@med.uni-heidelberg.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Kölker
authors.forename: Georg
authors.initials: G
authors.lastname: Köhr
authors.forename: Barbara
authors.initials: B
authors.lastname: Ahlemeyer
authors.forename: Jürgen G
authors.initials: JG
authors.lastname: Okun
authors.forename: Verena
authors.initials: V
authors.lastname: Pawlak
authors.forename: Friederike
authors.initials: F
authors.lastname: Hörster
authors.forename: Ertan
authors.initials: E
authors.lastname: Mayatepek
authors.forename: Josef
authors.initials: J
authors.lastname: Krieglstein
authors.forename: Georg F
authors.initials: GF
authors.lastname: Hoffmann
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins; D002412:Cations / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo; D004579:Electron Transport / Q000187:drug effects; D042967:Electron Transport Complex I; D042963:Electron Transport Complex II; D014450:Electron Transport Complex III / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D005977:Glutarates / Q000633:toxicity*; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D007668:Kidney / Q000166:cytology; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D025261:Mitochondrial Proton-Translocating ATPases; D009097:Multienzyme Complexes / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D009498:Neurotoxins / Q000494:pharmacology; D010088:Oxidoreductases / Q000378:metabolism; D018091:Receptors, AMPA / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000378:metabolism; D013687:Telencephalon / Q000166:cytology
chemical_list: C108959:3-hydroxyglutaric acid; D002352:Carrier Proteins; D002412:Cations; D005977:Glutarates; D008565:Membrane Proteins; D009097:Multienzyme Complexes; D009498:Neurotoxins; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D011994:Recombinant Proteins; D012964:Sodium; D010088:Oxidoreductases; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; D009247:NADH, NADPH Oxidoreductases; D003576:Electron Transport Complex IV; D000251:Adenosine Triphosphatases; D025261:Mitochondrial Proton-Translocating ATPases; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III; C020439:oligomycin sensitivity-conferring protein; D002118:Calcium