Iron loading exerts synergistic action via a different mechanistic pathway from that of acetaminophen-induced hepatic injury in mice

Abstract

Acetaminophen (APAP) overdose is a major cause of drug-induced acute liver failure. In such cases, free iron is released from lysosomes and is transported to mitochondria where it plays a pivotal role in APAP-induced liver injury. We previously reported that ascorbic acid (Asc) markedly mitigates APAP-induced hepatic damage in aldehyde reductase (Akr1a)-knockout (KO) mice that produce about 10% Asc as wild-type (WT) mice. However, the issue of the protective mechanism of Asc in association with the status of iron remains ambiguous. To gain additional insights into this issue, we examined effects of APAP (500 mg/kg) on female KO mice under conditions of iron loading. While the KO mice without AsA supplementation were more sensitive to APAP toxicity than the WT mice, FeSO₄ loading (25 mg/kg) to WT mice aggravated the hepatic injury, which was a similar extent to that of the KO mice. Supplementation of Asc (1.5 mg/ml in the drinking water) ameliorated KO mice irrespective of iron status but did not change the iron-mediated increase in the lethality in the WT mice. Hepatic cysteine and glutathione levels declined to similar extents in all mouse groups at 3 h irrespective of the iron status and largely recovered at 18 h after the APAP treatment when liver damage was evident. Asc prominently mitigated APAP toxicity in KO mice irrespective of the iron status but had no effect on the synergistic action of iron and APAP in the WT mice, suggesting that the mechanism for the deteriorating action of loaded iron is different from that of APAP toxicity.

Keywords:

• Ascorbic acid
• iron
• acetaminophen
• glutathione
• Akr1a

Acknowledgments

The authors thank Dr. Satoshi Miyata, Miyata Diabetes and Metabolism Clinic, 5-17-21 Fukushima, Fukushima-ku, Osaka 553-0003, Japan, for allowing us to use the Akr1a-knckout mice in this study.

Author contributions

G.M. performed majority of experiments. S.K. performed LC-MS analyses of amino acids. K.Y. provided the fluorescent probe for detecting Asc. J.F. conducted the study and wrote the article.

Disclosure statement

All authors declare no conflict of interest.

Additional information

Funding

This study was supported, in part, by JSPS and National Research Foundation (NRF) of Republic of Korea under the Japan – Korea Basic Scientific Cooperation Program to JF and, in part, by the YU-COE program [C31-3] to SK and JF from Yamagata University.