Acetaminophen hepatotoxicity in mice: Effect of age, frailty and exposure type

Abstract

Acetaminophen is a commonly used analgesic that can cause severe hepatotoxicity in overdose. Despite old age and frailty being associated with extensive and long-term utilization of acetaminophen and a high prevalence of adverse drug reactions, there is limited information on the risks of toxicity from acetaminophen in old age and frailty. This study aimed to assess changes in the risk and mechanisms of hepatotoxicity from acute, chronic and sub-acute acetaminophen exposure with old age and frailty in mice. Young and old male C57BL/6 mice were exposed to either acute (300 mg/kg via oral gavage), chronic (100 mg/kg/day in diet for six weeks) or sub-acute (250 mg/kg, t.i.d., for three days) acetaminophen, or saline control. Pre-dosing mice were scored for the mouse clinical frailty index, and after dosing serum and liver tissue were collected for assessment of toxicity and mechanisms. There were no differences with old age or frailty in the degree of hepatotoxicity induced by acute, chronic or subacute acetaminophen exposure as assessed by serum liver enzymes and histology. Age-related changes in the acetaminophen toxicity pathways included increased liver GSH concentrations, increased NQO1 activity and an increased pro- and anti-inflammatory response to acetaminophen in old age. Frailty-related changes included a negative correlation between frailty index and serum protein, albumin and ALP concentrations for some mouse groups. In conclusion, although there were changes in some pathways that would be expected to influence susceptibility to acetaminophen toxicity, there was no overall increase in acetaminophen hepatotoxicity with old age or frailty in mice.

Keywords: Acetaminophen; Ageing; Frailty; Hepatotoxicity; Liver; Mice; Paracetamol.

Fig. A.1

Liver necrosis for young and old male C57BL/6 mice from cohort 1 (A) or cohort 2 (B), 6 h after treatment with 300 mg/kg acetaminophen (grey bars) or saline (black bars), and cohort 3 (C) after treatment with either saline (black bars), 6 weeks of dietary chronic acetaminophen (checked grey bars) or 3 days of subacute acetaminophen dosing (striped grey bars). Data expressed as mean ± SEM. * = p < 0.05 compared to corresponding saline treated group.

Fig. 1

Serum alanine aminotransferase (ALT) concentrations for young and old male C57BL/6 mice from cohort 1 (A) and cohort 2 (B), 6 h after treatment with 300 mg/kg acetaminophen (grey bars) or saline (black bars) and cohort 3 (C) after treatment with either saline (black bars), 6 weeks of dietary chronic acetaminophen (checked grey bars) or 3 days of subacute acetaminophen dosing (striped grey bars). Data expressed as mean ± SEM. * = p < 0.05 compared to corresponding saline treated group. # = p < 0.05 compared to age-matched chronic treated group.

Fig. 2

Cytochrome (CYP)2E1 activity in the livers of young and old male C57BL/6 mice from cohort 1 (A) or cohort 2 (B), 6 h after treatment with 300 mg/kg acetaminophen (grey bars) or saline (black bars), and cohort 3 (C) after treatment with either saline (black bars), 6 weeks of dietary chronic acetaminophen (checked grey bars) or 3 days of subacute acetaminophen dosing (striped grey bars). Data expressed as mean ± SEM. * = p < 0.05 compared to corresponding saline treated group.

Fig. 3

Total liver glutathione (GSH) for young and old male C57BL/6 mice from cohort 1 (A) or cohort 2 (B), 6 h after treatment with 300 mg/kg acetaminophen (grey bars) or saline (black bars). Data expressed as mean ± SEM. * = p < 0.05 compared to corresponding saline treated group. # = p < 0.05 compared to corresponding young group. ^ = p < 0.05 compared to age-matched chronic treatment group.

Fig. 4

mRNA expression of inflammatory markers; (A) tumour necrosis factor (TNF)-α (B) interleukin (IL)-1β (C) IL-10 and (D) Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) for young and old male C57BL/6 mice from cohort 1, 6 h after treatment with 300 mg/kg acetaminophen (grey bars) or saline (black bars). Data expressed as mean normalized to young wild-type saline group ±SEM. * = p < 0.05 compared to corresponding saline treated group, # = p < 0.05 compared to corresponding young group.

Fig. 5

mRNA expression of (A) Caspase 3 (B) BAX (C) Peroxisome proliferator-activated receptor gamma coactivator (PGC)1-α and (D) PGC1-β for young and old male C57BL/6 mice from cohort 1, 6 h after treatment with 300 mg/kg acetaminophen (grey bars) or saline (black bars). Data expressed as mean normalized to young wild-type saline group ±SEM. * = p < 0.05 compared to corresponding saline treated group, # = p < 0.05 compared to corresponding young group.

Fig. 6

Correlation between frailty index and alanine aminotransferase (ALT), necrosis, cytochrome (CYP)2E1 activity, total liver glutathione (GSH), serum total protein, serum albumin, liver weight (as % of body weight) and Alkaline phosphatase (ALP) for old male C57BL/6 mice from cohort 2, treated with 300 mg/kg acetaminophen (grey) or saline (black).

Fig. 7

Correlation between frailty index and alanine aminotransferase (ALT), necrosis, cytochrome (CYP)2E1 activity, total liver glutathione (GSH), serum total protein, serum albumin, liver weight (as % of body weight) and Alkaline phosphatase (ALP) for old male C57BL/6 mice from cohort 3, treated with chronic acetaminophen (light grey), sub-acute acetaminophen (dark grey) or saline (black).