Inducible nitric oxide synthase is required in alcohol-induced liver injury: studies with knockout mice.
OBJECTIVE
Oxidative stress contributes to early alcohol-induced liver injury, and superoxide (O(2)*-) production from NADPH oxidase plays a key role. However, the production of the free radical nitric oxide (NO*) by inducible nitric oxide synthase (iNOS) could also be involved.


METHODS
To test this hypothesis, iNOS knockout (B6.129P2-Nos2 (tm1 Lau)) and wild-type mice were fed high-fat control or ethanol-containing diets for 4 weeks.


RESULTS
Mean body weight gains were not significantly different between treatment groups, and average urine ethanol concentrations were similar in wild-type and iNOS knockout mice. After 4 weeks, serum alanine aminotransferase (ALT) levels were increased significantly about 4-fold over control values (29 +/- IU/L) by enteral ethanol (113 +/- 20) in wild-type mice; this effect of ethanol was significantly blunted in iNOS knockout mice (50 +/- 9). Similar protective effects against liver damage were observed if wild-type mice were treated with the iNOS inhibitor N -(3-aminomethyl)benzyl-acetamindine (1400W). Enteral ethanol also caused severe fatty accumulation, mild inflammation, and necrosis in the liver in wild-type mice but had no effect in iNOS knockout mice. The accumulation of 4-hydroxynonenal (lipid peroxidation) and 3-nitrotyrosine (reactive nitrogen species formation) protein adducts caused by alcohol was completely blocked in iNOS knockout mice.


CONCLUSIONS
These data strongly support the hypothesis that iNOS is required for the pathogenesis of early alcohol-induced hepatitis by production of nitric oxide-derived pro-oxidants (e.g., peroxynitrite).
McKim
Stephen E
SE
Department of Pharmacology, University of North Carolina, Chapel Hill, USA.
Gäbele
Erwin
E
Isayama
Fuyumi
F
Lambert
Jason C
JC
Tucker
Lindsay M
LM
Wheeler
Michael D
MD
Connor
Henry D
HD
Mason
Ronald P
RP
Doll
Mark A
MA
Hein
David W
DW
Arteel
Gavin E
GE
D000410:Alanine Transaminase / Q000097:blood; D000447:Aldehydes / Q000378:metabolism; D000818:Animals; D001219:Aspartate Aminotransferases; D001835:Body Weight; D019392:Cytochrome P-450 CYP2E1 / Q000235:genetics; D004731:Endotoxins / Q000097:blood; D000431:Ethanol / Q000633:toxicity* / Q000652:urine; D005609:Free Radicals; D008099:Liver / Q000187:drug effects* / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019001:Nitric Oxide Synthase / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D000447:Aldehydes; D004731:Endotoxins; D005609:Free Radicals; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C002744:3-nitrotyrosine; D000431:Ethanol; D014443:Tyrosine; D019392:Cytochrome P-450 CYP2E1; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; C027576:4-hydroxy-2-nonenal