Effects of acute and chronic prednisolone treatment on serum zinc levels in rats with adjuvant arthritis.

Several studies in animals and humans have independently demonstrated that zinc metabolism is significantly affected either by inflammation or by glucocorticoid administration. The relative importance of these two factors was assessed in this study by the investigation of the effects on serum zinc concentrations of acute and chronic prednisolone treatments in adjuvant arthritis rats and in healthy controls animals. Acute steroid administration (3 mg/kg, i.p.) caused a rapid drop in serum zinc followed by a quick recovery, regardless to the fact that these concentrations were normal (healthy animals) or already reduced by the inflammatory process. However, the modification occurred faster in inflamed animals. Chronic steroid administration (0.58 to 0.78 mg/kg/day during 1 to 4 weeks) had a more complex effect. A previous experiment in healthy rats demonstrated that such a treatment only induced a slight decrease in serum zinc. In adjuvant arthritis animals, the early steroid treatment of the induced process promoted a further decrease in serum zinc level while a delayed treatment did not result in additional changes.