Tanioka Nohito, Shimizu Hiroko, Takahashi Toru, Omori Emiko, Kuroda Kosuke, Shibata Mari, Yamaoka Masakazu, Toda Yuichiro, Matsusaki Takashi, Morimatsu Hiroshi
Department of Anesthesiology and Resuscitology, Okayama University Medical School, Okayama 700-8558, Japan.
Department of Anesthesiology and Resuscitology, Okayama University Medical School, Okayama 700-8558, Japan ; Department of Health and Welfare Science, Okayama Prefectural University, Okayama 719-1197, Japan.
Biomed Rep. 2014 May;2(3):359-363. doi: 10.3892/br.2014.235. Epub 2014 Feb 7.
Hepatic oxidative stress is a major contributor to the pathogenesis of several acute liver diseases. Diagnostic markers of hepatic oxidative stress may facilitate early detection and intervention. Bach1 is an oxidative stress-responsive transcription factor that represses heme oxygenase 1 (HO-1), the rate-limiting enzyme in the catabolism of heme, a potent pro-oxidant. We previously demonstrated that carbon tetrachloride (CCl) causes oxidative hepatic injury in rats, exacerbated by free heme, suggesting that CCl may affect Bach1 gene expression. In the present study, we used northern blot analysis to measure Bach1, HO-1 and δ-aminolevulinate synthase (ALAS1; a heme biosynthesis enzyme) mRNA expression levels during acute hepatic injury induced by CCl (at doses of 0.1, 1.0 and 2.0 ml/kg body weight). Oxidative injury was assessed by measuring serum alanine aminotransferase (ALT), hepatic malondialdehyde (MDA) and glutathione (GSH) content. Treatment with CCl induced a significant dose-dependent increase in Bach1 mRNA 1-3 h after administration. Bach1 mRNA peaked at 6 h after CCl treatment (1 ml/kg), followed by a rapid decrease and gradual return to baseline by 12 h after treatment. The timecourse of transient Bach1 mRNA induction roughly mirrored that of HO-1 mRNA, while ALAS1 mRNA was inversely downregulated. Serum ALT levels and hepatic MDA concentration were significantly increased at 24 h after CCl treatment, while the hepatic GSH content was significantly reduced within 3 h of treatment. Serum ALT levels were positively correlated with Bach1 mRNA levels. These findings indicate that Bach1 mRNA is transiently induced in rat liver by CCl, possibly as a regulatory mechanism to restore HO-1 to baseline following free heme catabolism. Our findings also suggest that Bach1 mRNA expression may be a novel indicator of the extent of oxidative hepatic injury caused by free heme.
肝脏氧化应激是几种急性肝病发病机制的主要促成因素。肝脏氧化应激的诊断标志物可能有助于早期检测和干预。Bach1是一种氧化应激反应转录因子，它抑制血红素加氧酶1（HO-1），血红素分解代谢中的限速酶，一种强效的促氧化剂。我们之前证明四氯化碳（CCl）会导致大鼠肝脏氧化损伤，游离血红素会加剧这种损伤，这表明CCl可能影响Bach1基因表达。在本研究中，我们使用Northern印迹分析来测量在CCl（剂量为0.1、1.0和2.0 ml/kg体重）诱导的急性肝损伤期间Bach1、HO-1和δ-氨基乙酰丙酸合酶（ALAS1；一种血红素生物合成酶）的mRNA表达水平。通过测量血清丙氨酸氨基转移酶（ALT）、肝脏丙二醛（MDA）和谷胱甘肽（GSH）含量来评估氧化损伤。CCl处理后1-3小时，Bach1 mRNA出现显著的剂量依赖性增加。CCl处理（1 ml/kg）后6小时，Bach1 mRNA达到峰值，随后迅速下降，并在处理后12小时逐渐恢复到基线水平。Bach1 mRNA短暂诱导的时间进程大致反映了HO-1 mRNA的时间进程，而ALAS1 mRNA则被反向下调。CCl处理后24小时，血清ALT水平和肝脏MDA浓度显著升高，而处理后3小时内肝脏GSH含量显著降低。血清ALT水平与Bach1 mRNA水平呈正相关。这些发现表明，CCl在大鼠肝脏中短暂诱导Bach1 mRNA，这可能是一种调节机制，用于在游离血红素分解代谢后将HO-1恢复到基线水平。我们的研究结果还表明，Bach1 mRNA表达可能是游离血红素引起的肝脏氧化损伤程度的一种新指标。
