Effect of Cortisone on Collagenolytic Activity in the Rat 1

The action of cortisone on bone collagen and collagenolytic activity has been investigated. Rats were injected subcutaneously with cortisone acetate and the collagen content, the incorporation of ¹⁴C-proline into ¹⁴C-hydroxy-proline, and the collagenolytic activity of the control and cortisone-treated rat bones were determined. The effect of cortisone on bone collagenolytic enzyme was also assayed.

It was observed that cortisone administration caused a reduction of the collagen content and a decreased incorporation of ¹⁴C-proline into ¹⁴C-hydroxyproline. The collagenolytic activity of the bone was reduced and cortisone has also an inhibitory effect on bone collagenolytic enzyme. These results suggest that cortisone not only inhibits the biosynthesis of bone collagen but diminishes the collagenolytic activity of rat bone.

Cortisone and bone collagenolytic activity. Cortisone is known to affect the metabolism of several constituents of connective tissue (1, 2) and it has been repotred that the re-sorption of bone tissue is accompanied by degradation of bone collagen, presumably due to a collagenolytic enzyme liberated during bone resorption (3). It is well established that cortisone decreases the synthesis of the organic constituents of bone matrix including collagen. There are conflicting reports concerning the effect of glucocorticoids on bone resorption. There is some indication that the rate of bone resorption may be increased (4-7) depending upon the experimental model studied. Thus, far, no direct measurements of collagenolytic activity of rat bone following cortisone administration have been reported. The following experiments were carried out in order to determine whether any alterations in collagenolytic activity of rat bone were present.

Materials and Methods. Animals. Male Wistar rats weighing 30 g were injected subcutaneously with 1 mg and 5 mg of cortisone acetate suspended in 0.4 ml of saline.