Comparison of effects of chronic inflammation and long-term prednisolone administration on zinc metabolism in rats.

It is well known that plasma zinc is depressed in animals following administration of endotoxin, endogenous pyrogen, interleukin-1, and glucocorticoids. The modification is related to an induction of liver metallothionein causing an accumulation of the element in this organ. The changes in zinc metabolism induced by adjuvant arthritis in rats evidenced a redistribution of body zinc with a rapid and sustained decrease in plasma zinc that occurred simultaneously with an increase in liver zinc levels, and slower modification in erythrocyte and femur zinc concentrations. These effects were compared to those induced by a long-term corticosteroid administration in healthy rats. Male Wistar rats received either a commercially available complete maintenance diet or the same diet enriched with prednisolone at a level providing 1 mg prednisolone/kg body weight. Groups of animals were sacrificed after 3 or 5 weeks' treatment. Ingested food quantity, total body weight, total serum proteins and serum albumin were similar in treated and control rats. No significant modifications in parameters of zinc status could be observed after 3 weeks of treatment. However after 5 weeks, plasma zinc was significantly lower in treated rats as compared to controls, but modifications in liver, erythrocyte and femur zinc did not reach statistical significance. Changes induced by long-term corticosteroid administration are therefore less intense than those due to the inflammatory process of adjuvant arthritis.