Protective effect of aqueous extracts from Rhizopus oryzae on liver injury induced by carbon tetrachloride in rats

Hepatoprotective effects of Rhizopusoryzae/U-1 aqueous extract (RU) were demonstrated in carbon tetrachloride (CCl₄)-induced liver-injured rats. In order to investigate the RU effects, the rats were administered RU at a dose of 10 or 100mg/kg of body weight for 10 days before induction of the liver injury by oral administration of CCl₄ (125mg/kg body weight). (i) Pretreatment with RU caused a significant decrease in serum lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities that were increased by the administration of CCl₄. (ii) RU pretreatment (100mg/kg) increased 5-bromo-2′-deoxyuridine incorporation at 48h after CCl₄ treatment in hepatocytes. (iii) Histological hematoxylin and eosin staining of the liver showed that RU pretreatment reduced the damage induced by CCl₄ administration. (iv) Reverse transcriptase PCR analysis showed RU retreatment caused a transient but significant increase in hepatocyte growth factor (HGF) and a sustained and significant increase in insulin-like growth factor-I (IGF-I) gene expression in hepatocytes injured by CCl₄ treatment. From these results, we conclude that oral pre-administration of RU was effective to suppress liver injury induced by the subsequent oral CCl₄ administration, and RU-induced increase in IGF-I and HGF gene expression may be, even in part, involved in biological actions of RU in rats.