Effects of chronic prednisolone administration on plasma copper in rats with adjuvant arthritis.

Copper metabolism is known to be significantly affected by inflammation or by glucocorticoid administration. We have previously demonstrated that acute prednisolone administration induces a moderate but sustained increase in plasma copper in healthy rats while it induces a more pronounced but shorter increase in rats with adjuvant arthritis. In the present study we have investigated the effects of chronic prednisolone administration (around 0.65 mg/kg daily in food) in both healthy rats and rats with adjuvant arthritis at various stages of the disease. In healthy rats, a slight but significant increase of 11% was observed in plasma copper after 3 weeks of treatment. This modification was no longer apparent after 5 weeks of treatment. In arthritic rats, plasma copper was, as expected, higher than in healthy rats and reached a maximum 3 weeks after adjuvant injection. In prednisolone-treated arthritic rats, there was a sustained decrease in plasma copper starting after 2 weeks of treatment which could be correlated with an improvement of the clinical and biochemical signs of inflammation. In conclusion, chronic prednisolone treatment only slightly increases plasma copper in healthy rats while in arthritic rats plasma copper is dependent on the severity of the disease which is improved by the treatment.