RESUMO
Intravenous injection of BCG in rats induces protection against liver cell necrosis produced by CCl4. Impairment of hepatic mixed function oxidases by cytokines produced by activated Kupffer cells is the mechanism proposed to explain that protection. To verify the function of hepatic mixed function oxidases after Kupffer activation, the sleeping time after sodium pentobarbital anesthesia was evaluated in rats after intravenous injection of BCG. Male adult albino rats received BCG (50 mug, intravenous) and 48 h or 6 days after were anestethized with sodium pentobarbital (33 or 66 mg/g i.p.). The sleeping time was measured from the beginning of sleep until animal started having spontaneous movement and stand up on the forepaws. The results showed that the animals treated with BCG presented a significative increase in the sleeping time, indicating reduced inactivation of the pentobarbital, an indirect evidence of inhibittion of mixed function oxidase system. BCG treated rats showed hepatic and splenomegaly, both 48 and 6 days after treatment. Histology showed increase in number of mononuclear cells in the sinusoids in the liver and in the red pulp of the spleen 48 h after injection. Small epitheliod granulomas scattered in the hepatic lobules and in the red pulp were observed in rats killed six days after the BCG injection. Hepatocyte injury, induced by activated macrophages, would be not responsible for the reduced pentobarbital inactivation, because at six days there were several granulomas scattered in lobules, but the increase of sleep time in this group was similar to that observed in rats 48 h after injection of BCG. These results demonstrate that activation of Kupffer cells with BCG induces impairment of mixed function oxidase system soon as 48 h after injection of activator, probably due to production of IL-1, IL-6 and TNF alpha by activated Kupffer cells and other mononuclear cells migrated to the liver.
