Liver tissue damage is sustained in aged mice. (A) Hepatocytes around CVs lose HNF4α. HNF4α is thoroughly and exclusively expressed in hepatocytes in the adult liver. Both in young and aged livers, hepatocytes around CVs that are damaged by APAP lose nuclear HNF4α, whereas hepatocytes outside the damaged tissue thoroughly express HNF4α. Bars represent 100 μm. (B) Quantification of the HNF4α region. The damaged areas containing HNF4α- hepatocytes occupy approximately 50% of liver tissue at 8 and 24 hours after APAP administration in both young and aged mice. However, HNFα- areas are greatly reduced in young but not in aged mice at 48 hours. Average values with SEMs are presented in the graph.