Effect of tetracycline on synthesis of collagen and incorporation of 45calcium into bone in foetal and pregnant rats

Abstract

The effect of tetracycline on calcification and on the synthesis of collagen in both foetal and maternal bone was studied. 45Ca and 14C-proline were injected into pregnant rats and, after administration of tetracycline, the specific and total activities of 45Ca and 14C-hydroxyproline were determined. In the foetal calvaria, tetracycline reduced the amount of calcium and hydroxyproline, and the total activities of 45Ca and 14C-hydroxyproline were also significantly lower in the tetracycline-treated group than in the controls. Between the corresponding values for maternal femora there was no significant difference. The effect of tetracycline on the synthesis of soluble collagen in foetal skin was studied by determining the specific and total activities of 14C-hydroxyproline after injection of 14C-proline. Both the amount of hydroxyproline and the sp. act. of 14C-hydroxyproline in the soluble collagen of foetal skin were lower in the tetracycline-treated animals than in the controls, the total activity of 14C-hydroxyproline in the treated animals being only about one-third of that in the controls. The total incorporation of 14C-proline into the soluble protein fraction in the same foetal skin was not affected by tetracycline. The results of the present study suggest that tetracycline, when injected into pregnant rats in therapeutic doses, inhibits the calcification of foetal bones and the biosynthesis of collagen in foetal bone and skin but does not significantly affect the maternal tissues. In addition, the inhibition of collagen biosynthesis by tetracycline seems to be selective.