Perinatal development of cytochrome P-450, nadphcytochrome c reductase and ethoxycoumarin deethylase in rat liver nuclear membranes

Perinatal development of rat liver nuclear membrane enzymatic activities was investigated with respect to the metabolism of xenobiotica. The qualitative pattern observed was very close to that reported for microsomal enzymes during development. Cytochrome P-450, NADPH-cytochrome c reductase and ethoxycoumarin deethylase are already present in fetuses at 18 days of gestational age. Phenobarbital pretreatment appears to be effective as an inducing agent for all the enzymes studied, but only after birth. The pattern of induction of cytochrome P-450 showed a peak at the 38th day of life three times higher than basal values at that age. NADPH-cytochrome c reductase presented a constant elevation to about twice basal activity throughout the period taken into consideration. Ethoxycoumarin deethylase activity took only 17 days to reach the basal value observed later in adult animals. This enzyme proved highly inducible by phenobarbital (5-fold) early after birth but the increase dropped to 3-fold from the 24th day of life. © 1982.