Repeated administration of carbon tetrachloride to iron-overloaded rats induces severe liver injury with systemic hemorrhage

Abstract

We previously showed that experimental iron overload suppresses thioacetamide-induced rat liver fibrosis through the activation of Nrf2 system. Here we investigated the role of iron overload and Nrf2 system in rats with repeated administration of carbon tetrachloride (CCl4). Six-week-old male Nrf2 KO and wild-type (WT) rats were fed a high-iron diet (0.8% or 1% Fe) or a standard diet (0.02% Fe) for 4 weeks and then received a repeated administration with CCl4 (0.75 mL/kg, p.o., twice a week) for 4 weeks. WT rats with iron overload frequently died or became moribund in the middle of the CCl4 administration period; they had systemic hemorrhage (particularly in the limbs and mediastinal region) with elevation of hepatic enzymes. No abnormality was observed in the general condition of KO rats. Histopathologically, iron overload enhanced liver fibrosis in WT and KO rats. KO rats had more extensive fibrosis than WT rats, irrespective of dietary iron concentration, suggesting that Nrf2 system suppresses CCl4-induced liver fibrosis. Iron-overloaded rats with death or moribund condition had more severe hepatocellular injury than rats with planned necropsy. These results suggest that the combination of iron overload with CCl4 administration in the presence of Nrf2 system leads to the development of severe liver injury with systemic hemorrhage. Since the iron-overloaded rats potentially have a decreased activity of coagulation factors II and VII, it is suggested that the CCl4-induced liver injury can exacerbate the coagulation abnormality in the iron-overloaded rats.