THE UPTAKE OF 17β-OESTRADIOL IN BREAST TISSUE OF FEMALE RATS

Abstract

ABSTRACT The uptake of radioactivity in breast tissue after the injection of tritiated oestradiol in rats has been studied. The breast tissue accumulates more radioactivity per unit wet weight than skeletal muscle and fat, for at least 4 hours. The uptake of radioactivity does not, however, reach the high levels observed in the uterus. On the other hand, the uptake pattern found in the breast tissue corresponds to previous findings in other oestrogen responsive organs. The uptake of radioactivity by breast tissue in castrated rats is higher than in control animals with their ovaries intact. It is also found that simultaneous injection of non-radioactive oestradiol reduces the uptake of radioactivity. These findings may be explained as a competitive effect between non-labelled and labelled oestradiol. The accumulation of oestradiol observed may be consistent with the idea of a direct effect on breast tissue.