Estradiol replacement and dietary copper in ovariectomized rats additively increase the serum levels of HDL cholesterol and body status of copper
✍ Scribed by Ling Yang; Sung I. Koo
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 78 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0896-548X
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✦ Synopsis
The present study was conducted to determine the interactive effects of dietary copper (Cu) and estradiol (ES) on Cu status and serum HDL cholesterol in ovariectomized (OX) rats. Rats were divided into the following three groups of 12 each: 1) OX0 group: without ES replacement; 2) OXE group: with ES replacement (OXE); and 3) SM group: sham-operated with intact ovaries. After postoperative recovery for 3 weeks, the OXE rats were implanted subcutaneously with a 1.5 mg pellet of 17-estradiol, and the OX0 and SM rats were implanted with a placebo pellet. Each of the three groups was then subdivided into two groups: one was fed a Cu-deficient (-Cu) diet (0.99 g Cu/g), and the other a Cu-adequate (+Cu) diet (7.0 g Cu/g). Time course changes in serum HDL-cholesterol (HDL-C), ES, and Cu were determined. Serum HDL cholesterol was determined after separation of the HDL fraction by affinity chromatography. Serum ES was determined by radioimmunoassay. ES replacement sharply increased the concentrations of Cu in serum and liver regardless of whether rats were fed the -Cu or +Cu diet. ES replacement also produced a selective increase in HDL-C. It ranged from 1.5 to 2.2 mmol/L in OXE rats, whereas the range in OX0 was between 1.0 and 1.4 mmol/L, as determined at days 20, 40, and 60. Dietary Cu did not affect the concentrations of total serum or HDL cholesterol at days 20 and 40. However, at day 60, serum HDL-C was significantly lower in the rats fed the -Cu diet than in those fed the +Cu diet, independent of ES replacement. Serum HDL-C in all groups were correlated significantly with serum ES (r ס 0.60, P < 0.0006). Serum Cu was correlated highly with serum HDL cholesterol (r ס 0.66, P < 0.0001) and serum ES (r ס 0.64, P < 0.0001). The results provide evidence that ES replacement in OX rats selectively increases the serum levels of HDL cholesterol. The increase in serum HDL is independent of the nutritional status of Cu but is associated with a parallel rise in serum ES in response to ES replacement. The present finding and earlier observations, taken together, suggest a specific role of ES in protecting HDL during circulation and in improving the body status of Cu.