The effect of the sex hormones on the growth of transplanted mammary adenofibroma in rats.

Abstract

That transplantation of mammary adenofibroma is much more successful in female rats than in male rats has been shown by Loeb and Fleischer (1), Robinson and Grauer (2), Heiman (3), Picco (4), and Oberling, Guerin and Guerin (5). Castration of females, moreover, markedly reduces the percentage of takes, as shown by Heiman and Krehbiel (6), Picco (4), and Oberling et al (5). These findings suggest that one or both of the ovarian hormones may play a role in the transplantability of these benign mammary tumors. This conclusion is strengthened by the finding of Heiman and Krehbiel (6) that the injection of estrogenic hormone in combination with either gonadotropic or growth hormones of the anterior pituitary causes an increase in the number of takes in normal females, though none of these hormones had an appreciable effect when used alone. Similarly in castrates of both sexes the injection of estrogenic hormone plus gonadotropic hormone increased the percentage of takes. The injection of estrogenic hormone alone in castrates was not tried. The inference of Heiman and Krehbiel that estrogenic hormone must be accompanied by either gonadotropic or growth hormone for stimulation of mammary tumor growth is difficult to explain in view of the fact that neither of these pituitary hormones has any direct effect upon the mammary gland. Gonadotropic hormone would, of course, stimulate the secretion of estrogenic hormone by the ovary to bolster the action of that injected, but how growth hormone could have any effect is not apparent. In order to determine whether or not estrogenic hormone is, of itself, capable of influencing transplanted adenofibroma, the present experiments involving normal females, castrates of both sexes, and estrogen-injected castrates were undertaken.