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Department of Nutritional Sciences, University of California, Berkeley, California 94720
The purpose of this study was to see what effect glucocorticoids would have on bone density and mineral distribution in guinea pigs. Adult female guinea pigs were given prednisolone, a synthetic analogue of cortisol, for up to 24 weeks. Bone density and bone, liver and plasma levels of zinc, copper, iron, manganese, chromium, magnesium and calcium were studied in these animals. In one study, the effect of menopause was simulated by using ovariectomy. In another study, dietary calcium was varied to investigate its effect with glucocorticoids. Animals treated with 1 mg prednisolone/kg body weight showed increased femur density compared with controls, but no changes in tissue mineral concentrations. Animals fed 100 mg prednoisolone/kg body weight experienced decreased femur density. Differences in effects were not observed between ovariectomized and intact animals. Bone loss was greatest in animals fed the cereal-based closed-formula diet and least in animals fed the low-calcium diet. Changes in mineral content of femurs observed in animals which lost bone mass were increased iron concentration and decreased magnesium concentration. Total liver stores of zinc and magnesium increased. Liver copper increased in concentration per gram as well as in total content. Liver concentration of manganese decreased. Plasma changes in animals fed the high level of drug were decreased iron and calcium, and increased copper. Hemoglobin and hematocrit increased with increasing drug levels. It is suggested that glucocorticoids have marked effects on mineral metabolism which may be related to the bone loss and that these effects may be modified by dietary changes.
KEY WORDS: glucocorticoids trace minerals calcium magnesium bone density guinea pigs
1 This work was supported in part by USPHS 5 T1 GM1188 from the National Institutes of Health.
2 Taken in part from a thesis submitted by Judith Turniund in partial fulfillment of the requirement for the Ph.D. degree, Department of Nutritional Sciences, University of California, Berkeley, California, 1978.
Manuscript received 12 October 1978.