Serum alanine aminotransferase (ALT) concentration and histology grading of necrosis and inflammation for young (A, C, respectively) and old (B, D, respectively) mice fed either a control diet or paracetamol containing (1.33g/kg feed) diet for 6 weeks, then treated with 3 days of saline or paracetamol (250mg/kg × 3/day) plus a single or double dose of N-Acetyl Cysteine (NAC) (1200mg/kg) for the paracetamol diet group. Serum ALT activity data expressed as mean ± SEM. Histology data are presented as prevalence % of group. αp<0.05 compared to corresponding saline-treated group