Effect of HO-1 on hepatocyte apoptosis in mice fed with MCD diet at four weeks. (A) TUNEL staining for hepatocyte apoptosis in liver sections from mice administrated: control diet; MCD diet; MCD diet treated with hemin, ZnPP-IX, Ad-GFP, Ad-HO-1 and combination of Ad-HO-1 and hemin, respectively. (original magnification, × 400). (B) Quantitation of mean TUNEL-positive cells/field. are expressed as mean ± SD. *P < 0.01 compared with control; #P < 0.05, ##P < 0.01, compared with MCD feeding mice; $P < 0.01, compared with MCD+Ad-GFP treated mice. Slides are representative of 6 animals per group.