Differential inducibility of nuclear envelope epoxide hydratase by trans-stilbene oxide and phenobarbital
Gonzalez, F.J.; Kasper, C.B.
Molecular Pharmacology 21(2): 511-516
1982
ISSN/ISBN: 0026-895X PMID: 6808350 Document Number: 185059
Rough and smooth microsomal membranes and nuclear envelope were isolated from rat liver following the administration of trans-stilbene oxide or phenobarbital. These membranes were assayed for epoxide hydratase activity by using styrene oxide and benzopyrene 4,5-oxide. Quantitative immunochemical studies demonstrated that nuclear envelope epoxide hydratase was unresponsive to induction by phenobarbital. This conclusion was also supported by gel electrophoretic analysis of nuclear envelope from control and induced animals. Microsomal UDP-glucuronosyltransferase, NADPH-cytochrome c oxidoreductase and cytochrome P-450 were increased by both inducing agents; their nuclear envelope counterparts remained refractive to phenobarbital induction. Even though trans-stilbene oxide and phenobarbital induced similar spectra of enzymes and cytochromes in the endoplasmic reticulum, only trans-stilbene oxide induced nuclear envelope epoxide hydratase. The cellular controls regulating levels of nuclear envelope enzymes differed from those operative for the endoplasmic reticulum.