The effect of estrogen on copper and zinc status in the female rat
Forty female, Long-Evans hooded rats were used in this experiment to study the effects of estrogen administration on copper and zinc levels in serum, liver, kidney and brain. Twenty rats were treated for fourteen days with implants containing a mixture of 2.1 mg 17-/3 -estradiol and 4.0 mg cholesterol and 20 were implanted with cholesterol only to serve as controls. Half of the animals in each group were sacrificed after the two-week period. The remaining animals were reimplanted with the hormone preparation or cholesterol for a second two-week period and sacrificed after a total of 28 days. After four weeks of estrogen treatment, significant increases in serum copper (p < 0.001) and ceruloplasmin (p < 0.001) were observed when compared to control levels. No change in hepatic copper concentration was observed after two weeks. However, a significant decrease (p < 0.001) was seen after four weeks of treatment. In contrast, kidney copper levels rose significantly after two weeks (p < 0.001) but declined after four weeks to levels similar to those of control animals. Brain copper also increased (p < 0.005) after four weeks of estrogen administration. Decreased hepatic zinc concentrations after both two and four weeks of hormone treatment were the only significant changes in zinc levels (p < 0.005 and p < 0.001, respectively) observed between experimental and control groups. These results indicate that the high serum copper found with estrogen administration may be drawn from hepatic stores. This circulating copper appears to be retained temporarily in the kidney and later deposited in the brain. Changes in copper levels due to estrogen implantation did not appear to have an antagonistic effect on zinc levels in any of the tissues. Hepatic concentrations of both copper and zinc changed in the same direction following hormone treatment.