Inhibitory effect of rifampicin on the depressive action of interleukin-1 on cytochrome P-450-linked monooxygenase system

It has been shown that interleukin 1 (IL-l) depresses cytochrome P-450-link ed monooxygenases. In the present study, the effects of rifampicin on the d epressive action of IL-l on the activities and gene expression of xenobioti c metabolizing enzymes in liver microsomes were investigated in vivo using Wistar rats, Among the monooxygenases studied, we especially focused on the induction mechanism for CYP2D, known to be depressed by IL-l and responsib le for the oxidation of xenobiotics, debrisoquine, bufuralol, and sparteine . The CYP2D protein and its messenger RNA (mRNA) were quantitated by Wester n blot and slot blot hybridization analyses in the groups treated with and without rifampicin and IL-1. The results showed that the depressive action of IL-l on CYP2D was offset by additional administration of rifampicin, and the P-450 (CYP2D)-linked monooxygenase system is up-regulated at the mRNA level by rifampicin, These results show that rifampicin has a blocking effe ct on the depressive action of IL-l on the CYP2D subfamily. Copyright (C) 2 001 by W.B. Saunders Company.