https://phaidra.vetmeduni.ac.at/o:1640 Oxoglutarate dehydrogenase complex controls glutamate-mediated neuronal death Weidinger, Adelheid Adelheid Weidinger Ludwig Boltzmann Institute for Traumatology Kozlov, Andrey V. Andrey V. Kozlov Ludwig Boltzmann Institute for Traumatology Bunik, Victoria I. Victoria I. Bunik Lomonosov Moscow State University / Sechenov University Kagan, Valerian E. Valerian E. Kagan University of Pittsburgh Bayır, Hülya Hülya Bayır University of Pittsburgh Moldzio, Rudolf Rudolf Moldzio 0000-0002-1597-8402 University of Veterinary Medicine Vienna Tretter, Laszlo Laszlo Tretter Semmelweis University Pinelis, Vsevolod G Vsevolod G Pinelis Krasilnikova, Irina A Irina A Krasilnikova Surin, Alexander M Alexander M Surin Sharipov, Rinat R Rinat R Sharipov Trofimova, Lidia Lidia Trofimova Lomonosov Moscow State University Mkrtchyan, Garik V Garik V Mkrtchyan Lomonosov Moscow State University Vaglio-Garro, Annette Annette Vaglio-Garro Ludwig Boltzmann Institute for Traumatology Rauter, Laurin Laurin Rauter Ludwig Boltzmann Institute for Traumatology Törö, Gabor Gabor Törö University of Texas Szabo, Csaba Csaba Szabo University of Fribourg / University of Texas Duvigneau, J. Catharina J. Catharina Duvigneau University of Veterinary Medicine Vienna Hosmann, Arthur Arthur Hosmann Medical University of Vienna Milivojev, Nadja Nadja Milivojev Ludwig Boltzmann Institute for Traumatology Elsevier text eng Brain injury is accompanied by neuroinflammation, accumulation of extracellular glutamate and mitochondrial dysfunction, all of which cause neuronal death. The aim of this study was to investigate the impact of these mechanisms on neuronal death. Patients from the neurosurgical intensive care unit suffering aneurysmal subarachnoid hemorrhage (SAH) were recruited retrospectively from a respective database. In vitro experiments were performed in rat cortex homogenate, primary dissociated neuronal cultures, B35 and NG108-15 cell lines. We employed methods including high resolution respirometry, electron spin resonance, fluorescent microscopy, kinetic determination of enzymatic activities and immunocytochemistry. We found that elevated levels of extracellular glutamate and nitric oxide (NO) metabolites correlated with poor clinical outcome in patients with SAH. In experiments using neuronal cultures we showed that the 2-oxoglutarate dehydrogenase complex (OGDHC), a key enzyme of the glutamate-dependent segment of the tricarboxylic acid (TCA) cycle, is more susceptible to the inhibition by NO than mitochondrial respiration. Inhibition of OGDHC by NO or by succinyl phosphonate (SP), a highly specific OGDHC inhibitor, caused accumulation of extracellular glutamate and neuronal death. Extracellular nitrite did not substantially contribute to this NO action. Reactivation of OGDHC by its cofactor thiamine (TH) reduced extracellular glutamate levels, Ca2+ influx into neurons and cell death rate. Salutary effect of TH against glutamate toxicity was confirmed in three different cell lines. Our data suggest that the loss of control over extracellular glutamate, as described here, rather than commonly assumed impaired energy metabolism, is the critical pathological manifestation of insufficient OGDHC activity, leading to neuronal death. Nitric-Oxide; Excitotoxicity; Mitochondria; Vesicles; Pool http://creativecommons.org/licenses/by/4.0/ https://phaidra.vetmeduni.ac.at/api/object/o:1640/download 10.1016/j.redox.2023.102669 https://phaidra.vetmeduni.ac.at/o:605 application/pdf Redox Biology 62 (2023) Redox Biology 62 819.37 kB 2023