1. Sodium valproate induces mitochondrial respiration dysfunction in HepG2 in vitro cell model.
- Author
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Komulainen T, Lodge T, Hinttala R, Bolszak M, Pietilä M, Koivunen P, Hakkola J, Poulton J, Morten KJ, and Uusimaa J
- Subjects
- Adenosine Triphosphate metabolism, Cell Death drug effects, Cell Proliferation drug effects, Cell Respiration drug effects, Chemical and Drug Induced Liver Injury metabolism, Chemical and Drug Induced Liver Injury pathology, Dose-Response Relationship, Drug, Electron Transport Chain Complex Proteins metabolism, Galactose metabolism, Glucose metabolism, Hep G2 Cells, Hepatocytes metabolism, Hepatocytes pathology, Humans, Membrane Potential, Mitochondrial drug effects, Mitochondria, Liver metabolism, Mitochondria, Liver pathology, Mitochondrial Diseases metabolism, Mitochondrial Diseases pathology, Oxidative Stress drug effects, Pyruvic Acid metabolism, Reactive Oxygen Species metabolism, Superoxide Dismutase metabolism, Time Factors, Anticonvulsants toxicity, Chemical and Drug Induced Liver Injury etiology, Hepatocytes drug effects, Mitochondria, Liver drug effects, Mitochondrial Diseases chemically induced, Oxidative Phosphorylation drug effects, Valproic Acid toxicity
- Abstract
Sodium valproate (VPA) is a potentially hepatotoxic antiepileptic drug. Risk of VPA-induced hepatotoxicity is increased in patients with mitochondrial diseases and especially in patients with POLG1 gene mutations. We used a HepG2 cell in vitro model to investigate the effect of VPA on mitochondrial activity. Cells were incubated in glucose medium and mitochondrial respiration-inducing medium supplemented with galactose and pyruvate. VPA treatments were carried out at concentrations of 0-2.0mM for 24-72 h. In both media, VPA caused decrease in oxygen consumption rates and mitochondrial membrane potential. VPA exposure led to depleted ATP levels in HepG2 cells incubated in galactose medium suggesting dysfunction in mitochondrial ATP production. In addition, VPA exposure for 72 h increased levels of mitochondrial reactive oxygen species (ROS), but adversely decreased protein levels of mitochondrial superoxide dismutase SOD2, suggesting oxidative stress caused by impaired elimination of mitochondrial ROS and a novel pathomechanism related to VPA toxicity. Increased cell death and decrease in cell number was detected under both metabolic conditions. However, immunoblotting did not show any changes in the protein levels of the catalytic subunit A of mitochondrial DNA polymerase γ, the mitochondrial respiratory chain complexes I, II and IV, ATP synthase, E3 subunit dihydrolipoyl dehydrogenase of pyruvate dehydrogenase, 2-oxoglutarate dehydrogenase and glutathione peroxidase. Our results show that VPA inhibits mitochondrial respiration and leads to mitochondrial dysfunction, oxidative stress and increased cell death, thus suggesting an essential role of mitochondria in VPA-induced hepatotoxicity., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)
- Published
- 2015
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