Cytochrome P450 activities in pure and co-cultured rat hepatocytes. Effects of model inducers.
The stability and inducibility of several P450 activities (namely, P450 1A1; 2A1, 2B1/2, 2C11, and 3A1) were studied in rat hepatocytes co-cultured with the MS epithelial cell line derived from monkey kidney. The results revealed that these monooxygenase activities were systematically higher in co-cultures than in conventional hepatocyte cultures. Pure cultures showed a rapid loss of monooxygenase activities, which were undetectable after 5 days. In contrast, all isozymes assayed were measurable in co-cultured hepatocytes on Day 7 (about 15 to 40% of the initial activities of Day 0 of culture). The beneficial effects of the co-culture system seemed to be more selective for certain cytochrome P450 isoforms, with P450 1A1 and 3A1 being the best stabilized isozymes after 1 wk. A clear response to inducers was observed in co-cultures, each isozyme showing a different induction pattern. 3-Methylcholanthrene produced a strong increase in P450 1A1 (7-ethoxyresorufin O-deethylase) activity and a low increase in P450 2A1 (testosterone 7 alpha-hydroxylation), whereas no changes were observed in the other activities. Phenobarbital treatment resulted in increases in P450 2B1/2 (7-pentoxyresorufin O-depentylase and 16 alpha- and 16 beta-hydroxylation of testosterone) activities, while minor effects were observed on P450 3A1 (testosterone 6 beta-hydroxylation) activity. Dexamethasone markedly increased P450 3A1 (testosterone 6 beta- and 15 beta-hydroxylation) activity and, to a lesser extent, P450 2B1/2 (16 beta-hydroxylation).
Donato
M T
MT
Unidad de Hepatología Experimental, Hospital Universitario La Fe, Valencia, Spain.
Castell
J V
JV
Gómez-Lechón
M J
MJ
D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D019363:Cytochrome P-450 CYP1A1; D019362:Cytochrome P-450 CYP2B1; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D004848:Epithelium; D000882:Haplorhini; D007668:Kidney; D008099:Liver / Q000201:enzymology*; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology*; D010088:Oxidoreductases / Q000378:metabolism; D010634:Phenobarbital / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013739:Testosterone / Q000378:metabolism
D013739:Testosterone; D008748:Methylcholanthrene; D003907:Dexamethasone; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D019363:Cytochrome P-450 CYP1A1; D019362:Cytochrome P-450 CYP2B1; D010634:Phenobarbital