title: Protection afforded by pre- or post-treatment with 4-phenylbutyrate against liver injury induced by acetaminophen overdose in mice.
abstract: Acetaminophen (paracetamol, N-acetyl-p-aminophenol; APAP) is a widely used analgesic/antipyretic drug with few adverse effects at therapeutic doses; suicidal or unintentional overdose of APAP frequently induces severe hepatotoxicity. To explore a new and effective antidote for APAP hepatotoxicity, this study examined the effects of sodium 4-phenylbutyrate (4-PBA) on liver injury induced by APAP overdose in mice. Liver injury was induced in C57BL/6 male mice by intraperitoneal injection of APAP (400mg/kg). The effects of 4-PBA (100-200mg/kg) treatment at 1h before the APAP injection were evaluated with serum alanine aminotransferase (ALT) and blood ammonia levels, hepatic pathological changes, including histopathology, DNA damage, nitrotyrosine formation, and mRNA or protein expression involved in the development of hepatotoxicity, such as X-box binding protein-1 (XBP1), c-Jun N-terminal kinase (JNK), C/EBP homologous protein (CHOP) and B-cell lymphoma 2 interacting mediator of cell death (Bim). In addition, glutathione depletion and CYP2E1 protein expression, which are measures of the metabolic conversion of APAP to a toxic metabolite, were examined. Furthermore, we examined the effects of post-treatment with 4-PBA against APAP-induced hepatotoxicity in mice. When administered at 1h before APAP injection, 4-PBA significantly prevented the increase in serum ALT and blood ammonia levels, centrilobular necrosis of hepatocytes, DNA fragmentation, and nitrotyrosine formation induced by APAP in mice. 4-PBA also inhibited hepatic Xbp1 mRNA splicing and JNK phosphorylation induced by APAP, but did not suppress CHOP and Bim mRNA and protein expression. In addition, 4-PBA had little effect on hepatic glutathione depletion and CYP2E1 expression, parameters of toxic APAP metabolite production. Post-treatment with 4-PBA administration at 1 or 2h after APAP injection also attenuated the increase in serum ALT and blood ammonia levels and hepatic pathological changes in APAP-induced hepatotoxicity in mice. Although post-treatment with 4-PBA did not show any effects on hepatic Xbp1 mRNA splicing and JNK phosphorylation, it drastically attenuated the DNA fragmentation induced by APAP. The precise molecular mechanisms of the protection afforded by 4-PBA against APAP hepatotoxicity in mice are unclear, but they seem to involve inhibition of hepatocellular DNA fragmentation. We suggest that 4-PBA is a promising candidate as an antidote against APAP-induced liver injury.
authors.affiliation: Department of Clinical Chemistry and Informatics, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Shimizu
authors.affiliation: Department of Clinical Chemistry and Informatics, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan. Electronic address: y-zuka@gpo.kumamoto-u.ac.jp.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Ishitsuka
authors.affiliation: Department of Molecular Genetics, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan.
authors.forename: Keishi
authors.initials: K
authors.lastname: Miyata
authors.affiliation: Department of Clinical Chemistry and Informatics, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan.
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Tomishima
authors.affiliation: Department of Clinical Chemistry and Informatics, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kondo
authors.affiliation: Laboratory of Evidence-Based Pharmacotherapy, College of Pharmaceutical Sciences, Daiichi University, 22-1 Tamagawa-Cho, Minami-Ku, Fukuoka 815-8511, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Irikura
authors.affiliation: Iwawaki Lab, Advanced Scientific Research Leaders Development Unit, Gunma University, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Iwawaki
authors.affiliation: Department of Molecular Genetics, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Oike
authors.affiliation: Department of Clinical Chemistry and Informatics, Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan; Center for Clinical Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan.
authors.forename: Tetsumi
authors.initials: T
authors.lastname: Irie
mesh_terms: D000082:Acetaminophen; D000410:Alanine Transaminase / Q000097:blood; D000641:Ammonia / Q000097:blood; D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D000072224:Bcl-2-Like Protein 11; D056486:Chemical and Drug Induced Liver Injury / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000235:genetics; D005978:Glutathione / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010654:Phenylbutyrates / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D020011:Protective Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D011518:Proto-Oncogene Proteins / Q000235:genetics; D000071701:Regulatory Factor X Transcription Factors; D051742:Transcription Factor CHOP / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D000071717:X-Box Binding Protein 1
chemical_list: D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D004268:DNA-Binding Proteins; C497250:Ddit3 protein, mouse; D008565:Membrane Proteins; D010654:Phenylbutyrates; D020011:Protective Agents; D011518:Proto-Oncogene Proteins; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse; D051742:Transcription Factor CHOP; C002744:3-nitrotyrosine; D000082:Acetaminophen; D014443:Tyrosine; D000641:Ammonia; C075773:4-phenylbutyric acid; D019392:Cytochrome P-450 CYP2E1; D000410:Alanine Transaminase; D005978:Glutathione
keywords: Acetaminophen; Liver injury; Phenylbutyrate; X-box binding protein-1; c-Jun N-terminal kinase