Ceruloplasmin and Metallothionein Induction by Zinc and 13-cis-Retinoic Acid in Rats with Adjuvant Inflammation

The induction of ceruloplasmin and metallothionein was investigated in rats with the early inflammatory phase of adjuvant arthritis. When examined at the peak of the acute inflammatory response, 5 days after adjuvant treatment, zinc given daily (2 mg/kg, intraperitoneally) increased serum ceruloplasmin levels by 2.0 times that found in nonarthritic rats and 1.2 times that found in non-zinc-treated arthritic rats. 13-cis-Retinoic acid (160 mg/kg, orally) given daily increased serum ceruloplasmin 2.2 and 2.7 times that found in nontreated arthritic rats when given alone and with zinc (2 mg/kg, intraperitoneally), respectively. Reduction in the inflammatory response was measured by weight of the adjuvant-injected paw, 5 days after adjuvant was administered. The reduction in inflammation was 13 and 19-20% for 13-cis-retinoic acid and zinc, respectively, when given alone, and between 26 and 31% when the treatments were combined. Zinc markedly increased liver metallothionein levels whereas 13-cis-retinoic acid was a much less potent inducer of the protein in liver. The results are discussed in light of the probable physiological roles of both ceruloplasmin and metallothionein.