Hepatic steatosis prevents heme oxygenase-1 induction by isoflurane in the rat liver

AIM: To characterize the inductive effects of isoflurane (ISO) on hepatic heme oxygenase-1 (HO-1) in an animal model of hepatic steatosis. METHODS: Lean (LEAN) and obese (FAT) Zucker rats were randomized into 4 groups: 1: LEAN + pentobarbital sodium (PEN); 2: LEAN + ISO; 3: FAT + PEN; 4: FAT + ISO. The animals were mechanically ventilated for 6 h. In vitro analyses of liver tissue included determination of HO-1 mRNA and protein expression as well as measurement of HO enzyme activity and immunohistochemical analyses. RESULTS: Compared to PEN treatment, ISO administration profoundly induced hepatic HO-1 mRNA and protein expression and significantly increased HO enzyme activity in lean Zucker rats. In contrast, no difference in HO-1 gene expression was observed after ISO or PEN anesthesia in obese Zucker rats. CONCLUSION: The present study demonstrates that ISO is an inducer of hepatic HO-1 gene expression in non-steatotic organs but failed to upregulate HO-1 in steatotic livers.