Regulation of ceruloplasmin by retinoic acid in the developing rat

Ceruloplasmin (Cp), the major copper-binding protein in the plasma, is an acute phase protein with ferrioxidase activity. Both its oxidase activity and hepatic mRNA abundance increase during the developmental period. To test the possible role of retinoic acid, a derivative of vitamin A known to participate in cellular differentiation and development, on the developmental regulation of Cp, neonatal rat pups were injected with 2 micrograms 13-cis-retinoic acid (RA)/g body weight on postnatal day 1. Serum Cp activity and hepatic Cp mRNA were measured over the next 3 weeks in RA-treated and vehicle-treated controls. Serum Cp activity increased 2.5-fold 24 h after RA administration. However, hepatic Cp mRNA abundance was not elevated during this time period, suggesting that the action of RA on Cp activity was the result of post-transcriptional changes.