Role of apoptosis in acetaminophen hepatotoxicity.
Acetaminophen overdose causes liver injury by mechanisms involving glutathione depletion, oxidative stress and mitochondrial dysfunction. The role of apoptosis in acetaminophen-induced cell killing is still controversial. Here, our aim was to evaluate the mitochondrial permeability transition (MPT) as a key factor in acetaminophen-induced necrotic and apoptotic killing of primary cultured mouse hepatocytes. Acetaminophen (10 micromol/L) induced necrotic killing in approximately 50% of hepatocytes after 6 h and cyclosporin A (CsA), MPT inhibitor, temporarily decreased necrotic killing after 6 h, but cytoprotection was lost after 16 h. Confocal microscopy revealed mitochondrial depolarization and inner membrane permeabilization at approximately 4.5 h after acetaminophen. CsA delayed these changes indicative of the MPT to about 11 h after acetaminophen. TUNEL labeling and caspase 3 activation also increased after acetaminophen. Fructose (20 mmol/L, an ATP-generating glycolytic substrate) plus glycine (5 mmol/L, a membrane stabilizing amino acid) prevented nearly all necrotic cell killing but paradoxically increased apoptosis. In conclusion, acetaminophen induces the MPT and ATP-depletion-dependent necrosis or caspase-dependent apoptosis as determined, in part, by ATP availability from glycolysis.
Kon
Kazuyoshi
K
Department of Gastroenterology, Juntendo University School of Medicine, Tokyo, Japan. kazukon@med.juntendo.ac.jp
Ikejima
Kenichi
K
Okumura
Kyoko
K
Aoyama
Tomonori
T
Arai
Kumiko
K
Takei
Yoshiyuki
Y
Lemasters
John J
JJ
Sato
Nobuhiro
N
D000082:Acetaminophen / Q000493:pharmacokinetics / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002463:Cell Membrane Permeability; D002478:Cells, Cultured; D056486:Chemical and Drug Induced Liver Injury; D016572:Cyclosporine / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D051379:Mice; D018613:Microscopy, Confocal; D008930:Mitochondria, Liver / Q000187:drug effects; D009336:Necrosis / Q000473:pathology; D018384:Oxidative Stress
D000082:Acetaminophen; D016572:Cyclosporine; D005978:Glutathione