Induction of hepatic cytochrome P-450IA1 in pigeons treated in vivo with aroclor 1254 a commercial mixture of polychlorinated biphenyls (PCBS)

Abstract

1. Treatment with a commercial mixture of polychlorinated biphenyls (PCBs) resulted in highly significant increases in pigeon hepatic microsomal proteins (100-fold), cytochrome P-450 (11-fold), cytochrome b 5 (7-fold), NADPH-cytochrome c-(P450) reductase (7-fold), ethoxycoumarin- O-deethylation (9-fold), aldrin epoxidase (22-fold), ethoxyresorufin- O-deethylation (48-fold), N-demethylation of dimethylnitrosamine (28-fold) but not of lauric acid 12-hydroxylation. 2. SDS-PAGE analysis of pigeon hepatic microsomal proteins induced by Aroclor 1254 suggested highly significant increases in the density of staining in bands of estimated M r, 51–52 kD, 54–54.5 kD, 57–58 kD, 59–60 kD and of 77.5–78.5 kD. 3. The induction of cytochrome P-450IA1 was confirmed by Western immunoblotting using the monoclonal antibodies MAB 1-12-3 and MAB 1-8-4. 4. There was agreement between the 8-fold increase in cytochrome P-450IA1 increased staining of microsomal proteins, as judged by SDS-PAGE, and the 24-fold increase in the amount of protein that reacted with the monoclonal antibodies MAB 1-12-3 and MAB 1-8-4, as judged by Western immuno-blotting. 5. It is concluded that treatment with a commercial PCB mixture resulted in the induction of several isoforms of pigeon hepatic cytochrome P-450 in a fashion that is likely to be similar to that reported for mammals.