Effect of estrogen on the collagenolytic activity of rat bone

Rats were injected with 17 beta-estradiol benzoate intramuscularly and the collagenolytic activity of the rat bones was assayed by measuring the degradation of purified reconstituted 3H-proline- and 3H-hydroxyproline-labeled collagen. A diminution of the collagenolytic activity which could be recovered from the culture medium of estrogen-treated rat bone was observed. However, the addition of estrogen to the enzyme using the same assay revealed no diminution of collagenolytic activity. These results suggest that the diminution of collagenolytic activity in the culture medium of estrogen-treated rat bone is due to an alteration in the production or activation of collagenolytic activity.