Effect of hormones on ceruloplasmin and copper concentrations in the plasma of the rat

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.

Influence of synthetic corticosteroids on plasma zinc and copper levels in humans

The effects of varying doses of a short-acting (methylprednisolone) and a long-acting (dexamethasone) synthetic glucocorticoid on extent and duration of alterations in plasma zinc and copper concentrations in normal humans are documented. Early after intravenous administration of either steroid, increases in plasma zinc and copper levels were observed. By 12 hours, plasma zinc concentrations had decreased below control levels and the extent and duration of the depression depended on the dosage of the steroid administered. No significant decrease was noted beyond 48 hours. The plasma copper levels did not decrease until after zinc levels began returning toward normal, reaching a peak depression at 48 hours and, at high doses of steroids, persisting until completion of the study at 96 hours. This difference in the time sequence suggests that different mechanism control plasma concentrations of the two metals. The serum zinc levels may depend on ACTH-adrenal interactions, while the slower response of the serum copper levels may depend on changes in the rate of synthesis of the serum copper-binding protein, ceruloplasmin.

Zinc resorption from zinc-tape during wound healing. An experimental study in rats

In the rat zinc is resorbed from excisional wounds treated with adhesive zinc-tape. High levels of zinc compared to those in gauze-treated controls were found in serum, granulation tissue and pancreas. An increase of serum copper was also found during the process of wound healing, but increase in serum copper was probably due to an elevation of ceruloplasmin in serum.