Regulation of adrenal steroidogenesis by adrenaline expression of cytochrome P450 genes

Abstract

ABSTRACT The effect of adrenaline on the secretion of cortisol and cyclic AMP (cAMP) and on the accumulation of four different mRNAs encoding cholesterol side-chain cleavage cytochrome P450 (P450scc), 17α-hydroxylase cytochrome P450 (P45017α), 21-hydroxylase cytochrome P450 (P450c21) and 11β-hydroxylase cytochrome P450 (P45011β) was studied in bovine adrenocortical cells in primary culture and compared with the effects of ACTH. Treatment of cultured cells with adrenaline (1–100 μmol/l) showed a biphasic response in cortisol release over 1–24 h. Concentration of cAMP in the culture media increased from a basal level of <0·06 pmol/dish to a maximal level of 40·14 ± 8·9 pmol/dish with a half-maximal release of 20·07 pmol cAMP/dish in the medium reached 1·2 h after treatment with 10 μmol adrenaline/l. This stimulation resulted in an uniform increase in the levels of all four P450 mRNAs as revealed by Northern blot analysis. Increasing doses of adrenaline produced a maximal mRNA accumulation at a concentration of 10 μmol adrenaline/l. Incubation of the cells with 10 μmol adrenaline/l for 1–24 h produced a biphasic time-course with a half-maximal stimulation after about 5–6 h. Maximal stimulation with ACTH (100 nmol/l) caused different accumulations of the four mRNAs: P450sec mRNA increased twice as much and P45017α mRNA six times as much as the accumulation of P450c21 mRNA and P45011β mRNA, which was about ten-fold over basal values. Propranolol totally blocked the stimulatory effect of adrenaline but not the effect of ACTH. Our data suggest that the stimulatory effect of adrenaline upon de-novo cortisol formation is regulated in part at the transcriptional level in a dose- and time-dependent manner. The regulation requires β-adrenergic receptors and is due to a cAMP-mediated increase in the accumulation of all four P450 mRNAs. Journal of Endocrinology (1992) 135, 229–237