Synergetic signaling for apoptosis in vitro by ethanol and acetaminophen

Abstract

In vitro , ethanol in combination with acetaminophen induces hepatocyte apoptosis resembling immune-mediated fulminant hepatic failure in human beings. Intracellular pathways originating at the mitochondria are linked to apoptosis. I studied ethanol-induced apoptosis and hepatocytotoxicity after using an in vitro model of normal human primary hepatocytes that were exposed to 5 or 10 mM acetaminophen, 40 or 100 mM ethanol, 40 mM ethanol + 5 mM acetaminophen, or 40 mM ethanol + 10 mM acetaminophen, or nonexposed (control; plain medium). Transmission electron microscopy was performed at different time points after exposure to the various treatments. Apoptosis, as assessed by transmission electron microscopy, was increased in a time-dependent manner after exposure to ethanol + acetaminophen. In the ethanol + acetaminophen model, mitochondrial injury was associated with apoptosis of hepatocytes. Ultrastructural damage and induction of apoptosis were seen in response to N-acetyl-benzoquinone-imine plus ethanol, supporting the suggestion that the damage was due to the active metabolite of acetaminophen. The modulation of mitochondrial damage in vitro may have implications for the development of new therapeutic strategies to prevent apoptosis.