ALDH2 activity is decreased by ethanol and lead exposure: recovery by NAD+ and Alda-1 in neuroblastoma SHSY-5Y cells

DEZA PONZIO, ROMINA; ALBRECHT P.A.; FERNANDEZ-HUBEID, LUCIA E.; IRAZOQUI, FERNANDO J; RIVERA MEZA M; VIRGOLINI MB,

Congreso; IX International Meeting of the Latin American Society for Biomedical Research on Alcohol-ism (LASBRA); 2019

LASBRA

Clinical and experimental evidences in laboratory animals demonstrate that the neurotoxicant lead (Pb) induces neurobehavioral alterations, including an altered response to drugs. We have previously reported that perinatally-Pb-exposed rats showed elevated ethanol (EtOH) intake, which seems to be mediated by brain acetaldehyde (ACD) accumulation. Thus, based on a reduced brain mitochondrial ALDH (ALDH2) activity and expression observed in the Pb-exposed rats, in vitro experiments were performed in neuroblastoma SH-SY5Y cells, aimed to modulate ALDH2 activity in a brain like-environment. ALDH2 functionality depends on nicotinamide adenine dinucleotide (NAD+) availability, its cofactor which is generated within the mitochondria. Interestingly, activators such as Alda-1 were used to restore ALDH activity as a therapeutic strategy, not only in alcohol-related disorders but also in several brain conditions. Thus, neuroblastoma cells were exposed to Pb (5-200µM), EtOH (100-200 mM) or Pb plus EtOH (10µM/200mM) for 24 h. Moreover, NAD+ (1mM) and Alda-1 (20 µM) were used as therapeutic strategies to enhance ALDH2 activity in all groups. The results resembled the in vivo data showing that Pb alone (5µM and 10µM), EtOH alone (100-200 mM) and their combination inhibited ALDH2 activity in SH-SY5Y cells. Concomitant supplementation with NAD+ increased the enzyme activity in all groups (except the controls), suggesting either a reduction in NAD+ bioavailability or an altered affinity of the enzyme for its cofactor resultant of the combined neurotoxic effects of Pb and EtOH in these cells. Interestingly, Alda-1 treatment restored the enzyme activity in a higher ratio, suggesting a different mechanism of activation, probably related to its proposed protective role in ALDH2 inactivation by adduct formation of the enzyme and toxic bioproducts. Future experiments will be focused on the study of these activators in an in vivo model to evaluate their effects on the reported elevated EtOH consumption observed in the Pb-exposed rats.