Sodium valproate induces mitochondrial respiration dysfunction in HepG2 in vitro cell model.
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.
['Komulainen|Tuomas|T|', 'Lodge|Tiffany|T|', 'Hinttala|Reetta|R|', 'Bolszak|Maija|M|', 'Pietilä|Mika|M|', 'Koivunen|Peppi|P|', 'Hakkola|Jukka|J|', 'Poulton|Joanna|J|', 'Morten|Karl J|KJ|', 'Uusimaa|Johanna|J|']
D000255:Adenosine Triphosphate D000927:Anticonvulsants D016923:Cell Death D049109:Cell Proliferation D019069:Cell Respiration D056486:Chemical and Drug Induced Liver Injury D004305:Dose-Response Relationship, Drug D045222:Electron Transport Chain Complex Proteins D005690:Galactose D005947:Glucose D056945:Hep G2 Cells D022781:Hepatocytes D006801:Humans D053078:Membrane Potential, Mitochondrial D008930:Mitochondria, Liver D028361:Mitochondrial Diseases D010085:Oxidative Phosphorylation D018384:Oxidative Stress D019289:Pyruvic Acid D017382:Reactive Oxygen Species D013482:Superoxide Dismutase D013997:Time Factors D014635:Valproic Acid
Sodium valproate Mitochondrial respiration HepG2 Hepatotoxicity Reactive oxygen species Mitochondrial toxicity