Complementary DNA clones specific for cytochromes P-450c and P-450d were used to study the expression of corresponding mRNAs in the rat ventral prostate. Following treatment with beta-naphthoflavone (BNF), an increase in total cellular levels of cytochrome P-450c mRNA was observed in this tissue. The induction kinetics were similar in both rat liver and prostate with regard to the expression of the cytochrome P-450c gene. The mRNA levels reached a maximum at 16 h and decreased to control levels at about 48 h. In contrast, mRNA specific for cytochrome P-450d was detectable only in the liver following BNF treatment (maximum at 24 h). The tissue-specific expression of cytochromes P-450c and P-450d was further investigated using measurements of nuclear transcription in vitro. RNA transcripts specific for cytochrome P-450c were detected in nuclei from both liver and prostate following BNF induction. The rate of cytochrome P-450c transcription was maximal at 4 h and 8-12 h in the liver and prostate, respectively. In the liver, induction by BNF of the rate of transcription of the cytochrome P-450d gene occurred at a slightly later time point as compared to cytochrome P-450c gene expression. No elongation of RNA specific for cytochrome P-450d could be detected in nuclei from the ventral prostate indicating a transcriptional control of cytochrome P-450d gene expression in this tissue.