Effect of Glucocorticoids and Zinc Deficiency on Femur and Liver Zinc in Rats

Male weanling rats were fed diets containing < 1, 3, 6, or 13 ppm zinc or stock rat diet for 3 weeks. Each dietary group was subdivided into a control group and a prednisolone-treated group (5 mg pred/kg body weight). Femur and liver zinc contents were determined by flame atomic absorption spectrophotometry. Prednisolone caused growth retardation at all levels of dietary zinc. A marked increase was seen in femur zinc content of prednisolone-treated rats fed zinc-deficient diets. No such increase was seen in rats fed diets adequate in zinc. No significant change was seen in liver zinc content of zinc-deficient rats due to prednisolone. By comparing femur zinc in rats fed zinc-deficient diets with femur zinc in weanling rats, it appears that prednisolone causes an increase in femur zinc in rats fed deficient diets by (a) preventing bone resorption, and (b) increasing femur uptake of dietary zinc. Because the effects of glucocorticoids in rats appear to differ from effects in man, similar studies in other species are recommended.