Perinatal Development of Cytochrome P-450, Cytochrome C Reductase, Aryl Hydrocarbon Hydroxylase, Styrene Monooxygenase, and Styrene Epoxide Hydrolase in Rabbit Liver Microsomes and Nuclei

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Abstract
The development of cytochrome P-450, cytochrome C reductase, aryl hydrocarbon hydroxylase, styrene monooxygenase, and styrene epoxide hydrolase was studied in fresh rabbit liver nuclear and microsomal preparations. Enzymatic activities were determined in rabbit fetus at 21 and 30 days of gestation and in rabbits at 1,5, 11,22, 44, and 60 days of age. In extrauterine life, nuclear cytochrome P-450, aryl hydrocarbon hydroxylase, and styrene epoxide hydrolase were found to develop later than their microsomal counterparts, whereas nuclear cytochrome C reductase developed earlier than its microsomal counterpart. The behavior of styrene monooxygenase was more complex. The only activities detectable before birth were styrene epoxide hydrolase, styrene monooxygenase, and cytochrome C reductase in both nuclei and microsomes. The microsomes- to-nuclei epoxide hydrolase activity ratio was almost ten times the microsomes-to-nuclei styrene monooxygenase ratio, indicating a dissociation in the development of the two enzymes in rabbits. Nuclear metabolic activity was high at all ages, suggesting possible toxicological relevance.