Dose- and time-dependent effects of luteolin on carbon tetrachloride-induced hepatotoxicity in mice

Carbon tetrachloride (CCl4) is a well-known model compound for producing chemical hepatic injury. This study investigated the protective effects of the flavonoid luteolin on the CCl4-induced hepatotoxicity in mice. Luteolin dissolved in dimethyl sulfoxide (DMSO) was administered intraperitoneally (i.p.) at 5 or 50 mg/kg as a single dose, and once daily for 2 consecutive days. Two hours after the final treatment, the mice were treated with CCl4 (20 mg/kg, i.p.). CCl4-induced hepatotoxicity was reduced in a dose- and time-dependent manner, as determined by decreased serum aminotransferase activities and liver histopathology. CCl4 intoxication resulted in an overexpression of heat shock protein gp96 in the mice liver, which was strongly attenuated by luteolin pretreatment. Luteolin has also decreased oxidative stress produced by CCl4, as suggested by improvement in the Cu/Zn superoxide dismutase activity. The effect of luteolin on myeloperoxidase, an indicator of inflammatory cell infiltration, was also investigated. Treatment of the mice with luteolin resulted in a significant decrease in the myeloperoxidase activity. The hepatoprotective effect of luteolin against CCl4 hepatotoxicity was higher in animals pretreated with luteolin for 2 consecutive days. This suggests that the protection might be due to induction of some adaptive mechanisms. The data indicate that luteolin could be effective in protecting mice from the hepatotoxicity produced by CCl4.