Regulatory effect of copper on rat adrenal cytochrome P-450 and steroid metabolism.
Accumulation of Cu2+ in rat adrenal glands produced a biphasic response in concentrations of the mitochondrial cytochrome P-450 and heme which were, in turn, reflected in abnormal steroid biosynthesis and output. In the mitochondria, 1 day after Cu2+ treatment, when the concentration of the metal ion was increased by 2- to 3-fold over the control value, a significant increase in cytochrome P-450-dependent steroid 11 beta-hydroxylase activity was observed. These effects were accompanied by a nearly 85% increase in concentrations of cytochrome P-450 and heme. In addition, the activity of delta-aminolevulinate synthetase was increased by 3-fold. In those animals lipid peroxidation, assessed by measuring concentrations of conjugated dienes, was reduced to approximately 50% of the control value. However, after 7 days of Cu2+ treatment (via a mini-osmotic pump), a significantly lowered rate of 11 beta-hydroxylase activity was noted, and the plasma concentration of corticosterone was also reduced significantly. Also, in the mitochondria, the concentrations of cytochrome P-450 and heme were decreased in comparison with the control values. These decreases were accompanied by elevated levels of the mitochondrial lipid peroxidation and a further increase in adrenal Cu2+ content (5-fold). At this time, delta-aminolevulinate synthetase activity remained elevated but to a lower extent than that observed after 1 day of Cu2+ treatment. In contrast to 11 beta-hydroxylase activity, the reduction in cytochrome P-450 content was not reflected in a decrease in the rate of cholesterol side-chain cleavage; rather this activity was increased in Cu2+-treated animals. Adrenal heme oxygenase activity was unaffected by either Cu2+ treatment, as was the specific content of cytochrome P-450 in the microsomal fraction. The present findings suggest that the Cu2+-mediated regulation of cytochrome P-450-dependent steroidogenic activity in the adrenal mitochondria is predominantly a reflection of the metal ion affecting heme biosynthesis and lipid peroxidation in this organ. Moreover, these actions appear to differentially affect the mitochondrial cytochrome P-450 species catalyzing different hydroxylation reactions in the adrenal steroidogenesis pathway.
D000624:5-Aminolevulinate Synthetase / Q000032:analysis; D000311:Adrenal Glands / Q000187:drug effects* / Q000378:metabolism; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000032:analysis; D003300:Copper / Q000378:metabolism / Q000494:pharmacology*; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis*; D006418:Heme / Q000032:analysis; D006420:Hemeproteins / Q000032:analysis; D008054:Lipid Peroxides / Q000378:metabolism; D008297:Male; D008861:Microsomes / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013252:Steroid 11-beta-Hydroxylase / Q000032:analysis; D013256:Steroids / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000032:analysis
D006420:Hemeproteins; D008054:Lipid Peroxides; D013256:Steroids; D006418:Heme; D003300:Copper; D000324:Adrenocorticotropic Hormone; D003577:Cytochrome P-450 Enzyme System; D013252:Steroid 11-beta-Hydroxylase; D002786:Cholesterol Side-Chain Cleavage Enzyme; D013482:Superoxide Dismutase; D000624:5-Aminolevulinate Synthetase