Nicotinamide adenine dinucleotide attenuates acetaminophen-induced acute liver injury via activation of PARP1, Sirt1, and Nrf2 in mice

The aim of this study was to investigate the protective effect of nicotinamide adenine dinucleotide (NAD+) against acute liver injury (ALI) induced by acetaminophen (APAP) overdose in mice. First, serum transaminases were used to assess the protective effect of NAD+, and the data revealed that NAD+ mitigated the APAP-induced ALI in a dose-dependent manner. Then, we performed hematoxylin-eosin staining of liver tissues and found that NAD+ alleviated the abnormalities of histopathology. Meanwhile, increase in the malondialdehyde content and decrease in glutathione, superoxide dismutase (SOD), and glutathione peroxidase were identified in the APAP group, which were partially prevented by the NAD+ pretreatment. Moreover, compared with the mice treated with APAP only, the expression of poly ADP-ribose polymerase 1 (PARP1), Sirtuin1 (Sirt1), SOD2, nuclear factor erythroid 2-related factor 2 (Nrf2), and hemoxygenase-1 was upregulated, while Kelch-like ECH-associated protein 1 and histone H2AX phosphorylated on Ser-139 were downregulated by NAD+ in NAD+ + APAP group. Conversely, NAD+ could not correct the elevated expression of phospho-Jun N-terminal kinase and phospho-extracellular signal-regulated kinase induced by APAP. Taken together, these findings suggest that NAD+ confers an anti-ALI effect to enhance the expression of PARP1 and Sirt1, and to simultaneously stimulate the Nrf2 anti-oxidant signaling pathway.