ALDH2 inhibition by Lead and Ethanol co-exposure: impact on bi-oenergetics and oxidative stress biomarkers in SH-SY5Y cells

DEZA PONZIO ROMINA; EICHWALD TUANY; GARAY YOHANA; IRAZOQUI F; LATINI A; VIRGOLINI MB,

Congreso; NeuroToxicity Society (modalidad virtual); 2021

ALDH2 inhibition by Lead and Ethanol co-exposure: impact on bioenergetics and oxidative stress biomarkers in SH-SY5Y cellsRomina Deza-Ponzio1, Tuany Eichwald3, Yohana Garay2, Fernando J Irazoqui2, Alexandra Latini3 and Miriam B. Virgolini1.1IFEC-CONICET. Departamento de Farmacología. Facultad de Ciencias Químicas. Universidad Nacional de Córdoba, Córdoba, Argentina 2CIQUIBIC-CONICET. Departamento de Química Biológica. Facultad de Ciencias Químicas. Universidad Nacional de Córdoba, Córdoba, Argentina 3Departamento de Bioquímica, Centro de Ciencias Biológica, Universidad Federal de Santa Catarina, SC, Brasil.rdezaponzio@unc.edu.ar We have previously reported that perinatally-Pb-exposed rats showed elevated ethanol (EtOH) intake, which seems to be mediated by brain acetaldehyde (ACD) accumulation, a highly reactive metabolite. Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial oxidoreductase that metabolizes ACD to acetate during EtOH metabolism, with NAD+ as the limiting factor of the reaction, a cofactor that is recycled within the mitochondria. Based on a reduced brain ALDH2 activity and expression observed in the Pb-exposed rats, in vitro experiments were performed in SH-SY5Y cells in an attempt to elucidate the mechanisms underlying ALDH2 defective function in the presence of Pb and EtOH. Thus, whole intact neuroblastoma cells exposed for 24 h to Pb (10 µM), EtOH (200 mM), or their combination were analyzed in an Oxygraph Oroboros 2K for oxygen consumption rates. In addition, to evaluate their redox status, cells were harvested and homogenized with the supernatant used for the measurement of ALDH2 activity and expression as well as total reactive oxygen species (ROS), thiobarbituric acid reactive substances (TBARs) formed as a byproduct of lipid peroxidation generation, and catalase activity and expression. The results obtained replicated the in vivo data in terms of ALDH2 inhibition after exposure to Pb, EtOH, or their combination. High-resolution respirometry shows that Pb and EtOH co-exposure decreased routine and maximal respiratory capacity in addition to the mitochondrial oxygen reserve capacity. On the other hand, Pb and EtOH exposure increased ROS levels, lipid peroxidation and catalase activity and expression, probably as a compensatory mechanism aimed to reestablish the oxidative balance in the cell. It can be concluded that Pb and EtOH exposure causes mitochondrial toxicity by altering bioenergetics in SH-SY5Y cells, with possible consequences on NAD+ availability and thereby ALDH2 functionality, as previously showed in other experiments. Thus, whether oxidative stress follows mitochondrial dysfunction or the opposite, is a fact that deserves consideration in the context of a low-functional ALDH2 enzyme as a consequence of exposure to these neurotoxicants.