Acetaminophen (APAP) overdose causes hepatotoxicity involving mitochondrial dysfunction.
Previous studies showed that translocation of Fe 2+ from lysosomes into mitochondria
by the mitochondrial Ca 2+ uniporter (MCU) promotes the mitochondrial permeability
transition (MPT) after APAP. Here, our Aim was to assess protection by iron chelation
and MCU inhibition against APAP hepatotoxicity in mice. C57BL/6 mice and hepatocytes
were administered toxic doses of APAP with and without starch-desferal (an iron chelator),
minocycline (MCU inhibitor), or N-acetylcysteine (NAC). In mice, starch-desferal and
minocycline pretreatment decreased ALT and liver necrosis after APAP by >60%. At 24
h after APAP, loss of fluorescence of mitochondrial rhodamine 123 occurred in pericentral
hepatocytes often accompanied by propidium iodide labeling, indicating mitochondrial
depolarization and cell death. Starch-desferal and minocycline pretreatment decreased
mitochondrial depolarization and cell death by more than half. In cultured hepatocytes,
cell killing at 10 h after APAP decreased from 83% to 49%, 35% and 27%, respectively,
by 1 h posttreatment with minocycline, NAC, and minocycline plus NAC. With 4 h posttreatment
in vivo , minocycline and minocycline plus NAC decreased ALT and necrosis by ~20%
and ~50%, respectively, but NAC alone was not effective. In conclusion, minocycline
and starch-desferal decrease mitochondrial dysfunction and severe liver injury after
APAP overdose, suggesting that the MPT is likely triggered by iron uptake into mitochondria
through MCU. In vivo , minocycline and minocycline plus NAC posttreatment after APAP
protect at later time points than NAC alone, indicating that minocycline has a longer
window of efficacy than NAC.