3-methyadenine attenuates chloroform-induced hepatotoxicity via autophagy activation

Chloroform is a common contaminant in the drinking water. Exposure of human to chloroform leads to severe hepatotoxicity. In the present study, chloroform-induced acute liver injury was investigated in mice using 3-methyadenine (3-MA), a common autophagy inhibitor. At 24 h after intraperitoneal injection of 0.5 mL/kg chloroform, serum alanine aminotransferase (ALT) levels were increased significantly; extensive necrosis and inflammation occurred as identified by histological examinations. Moreover, chloroform induced an increase in lipid peroxidation as demonstrated by increased formation of malondialdehyde (MDA) in the liver tissues. Hepatic antioxidants including glutathione (GSH) and superoxide dismutase (SOD) were decreased by chloroform treatment. All these changes were significantly inhibited by 3-MA treatment. Further mechanistic insights demonstrated that chloroform up-regulated pro-inflammatory cytokine, IL-1β, in the livers and blood, which was suppressed by 3-MA. Surprisingly, Western blots results showed that after 24-hours of chloroform treatment 3-MA activated autophagy as indicated by decreased levels of LC3B II and p62 protein. Co-treatment of chloroquine with 3-MA to inhibit autophagy would abrogate the hepatoprotection of 3-MA in chloroform hepatotoxicity. Taken together, findings in the present study suggested that a widely-used autophagy inhibitor, 3-MA, significantly reduced chloroform hepatotoxicity in mice via autophagy activation. Findings in this study also suggested that caution should be exercised when using 3-MA to modulate autophagy in vivo.