Effect of endotoxin treatment and tumour induction on liver catalase activity in mice

Catalase activity in liver homogenates was studied in normal and low endotoxin (LPS)-responder mice treated with various doses of LPS from S. typhimurium B or bearing tumours induced by 3-methylcholanthrene. In normal LPS-responder (C3H/f) mice a dose of 40 micrograms LPS or tumour induction caused a reduction of catalase activity of about 50%. In low responder (C3H/HeJ) mice a reduction of the enzyme activity of over 40% was observed at a dose of 200 micrograms LPS. Tumour induction had no effect. In tumour-bearing mice of both strains the presence of a tumour seemed to interfere with the ability of LPS to depress hepatic catalase activity. Since a reduction of the enzyme activity in response to LPS or tumour induction seemed to be influenced by the LPS responsiveness of the mice, this study suggests that there could be common mediators of this effect. It is also possible that tumour induction might influence host responses to LPS.