Oxidant stress-induced liver injury in vivo: role of apoptosis, oncotic necrosis, and c-Jun NH2-terminal kinase activation.
Oxidant stress is critically involved in various liver diseases. Superoxide formation causes c-Jun NH2-terminal kinase (JNK)- and caspase-dependent apoptosis in cultured hepatocytes. To verify these findings in vivo, male Fisher rats were treated with diquat and menadione. The oxidant stress induced by both compounds was confirmed by increased formation of glutathione disulfide and 4-hydroxynonenal protein adducts. Plasma alanine aminotransferase activities increased from 46+/-4 U/l in controls to 955+/-90 U/l at 6 h after diquat treatment. Hematoxylin and eosin staining of liver sections revealed large areas of necrotic cells at 3 and 6 h. DNA strandbreaks, evaluated with the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, showed clusters of TUNEL-positive cells, where the staining was predominantly cytosolic and the cells were swollen, indicating oncotic necrosis. There was no significant increase in caspase-3 activities or relevant release of DNA fragments into the cytosol at any time between 0 and 6 h after diquat treatment. Despite the activation of JNK after high doses of diquat, the JNK inhibitor SP-600125 did not protect against diquat-induced necrosis. Menadione alone did not cause liver injury, but, in combination with phorone and FeSO4, induced moderate oncotic necrosis. On the other hand, if animals were treated with galactosamine/endotoxin as positive control for apoptosis, caspase-3 activities were increased by 259%, the number of TUNEL-positive cells with apoptotic morphology was increased 103-fold, and DNA fragmentation was enhanced 6-fold. The data indicate that liver cell death initiated by diquat-induced superoxide formation in vivo is mediated predominantly by oncotic necrosis and is independent of JNK activation.
Hong
Ji-Young
JY
Department of Pharmacology, Toxicology & Therapeutics, University of Kansas Medical Center, 3901 Rainbow Blvd, MS 1018, Kansas City, KS 66160, USA.
Lebofsky
Margitta
M
Farhood
Anwar
A
Jaeschke
Hartmut
H
D000410:Alanine Transaminase / Q000097:blood; D000447:Aldehydes / Q000378:metabolism; D000818:Animals; D000933:Antifibrinolytic Agents / Q000633:toxicity; D017209:Apoptosis / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D056486:Chemical and Drug Induced Liver Injury; D053938:DNA Fragmentation; D004178:Diquat / Q000633:toxicity; D004195:Disease Models, Animal; D004731:Endotoxins / Q000633:toxicity; D005688:Galactosamine / Q000633:toxicity; D019803:Glutathione Disulfide / Q000378:metabolism; D022781:Hepatocytes / Q000378:metabolism / Q000473:pathology; D020287:In Situ Nick-End Labeling; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008107:Liver Diseases / Q000378:metabolism* / Q000473:pathology*; D008297:Male; D009336:Necrosis; D018384:Oxidative Stress / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D013481:Superoxides / Q000378:metabolism; D024483:Vitamin K 3 / Q000633:toxicity
D000447:Aldehydes; D000933:Antifibrinolytic Agents; D004731:Endotoxins; D013481:Superoxides; D024483:Vitamin K 3; D005688:Galactosamine; D004178:Diquat; D000410:Alanine Transaminase; D048031:JNK Mitogen-Activated Protein Kinases; D020169:Caspases; C027576:4-hydroxy-2-nonenal; D019803:Glutathione Disulfide