Abstract
The uptake of 3H-estradiol in several tissues (uterus, pituitary, hypothalamus) and serum of rats was measured on 17, 21 and 25 days of age.
3H-estradiol (Estradiol-6, 7-3H 39.7 Ci/m mol) was soluted to twenty percent ethanol and 1 μCi/0. 1 ml per rat (Exp. I) and 1 μCi/0. 1 ml per 50 g body weight (Exp. II) was injected subcutaneously.
The tissue of autopsied rat was extracted with soultion of acetonethanol (1 : 1). The serum was collected 0.1 ml per rat. These samples were dried and the scintillating solution was added. The radioactivity of these samples was measured with liquid scintillation counter. In order to examine the relation between the time of injection and the time of the slaughter, the radioactivity was measured in rats slaughtered at 5, 30, 60 and 240 minutes after injection of 3H-estradiol (Fig. 1).
The equilibrium of uptake of 3H-estradiol reached in all tissues about 60 minutes after injection. Then, the uptake of 3H-estradiol per whole tissue and tissue weight (mg) was measured at 60 minutes after injection.
The results are as follows:
1. In uterus, the uptake of 3H-estradiol per tissue weight decreased significantly from 17 to 21 days of age (Exp. I, II). The increased level of counts per both whole tissue and tissue weight was observed at 25 days of age (Exp. II).
2. In pituitary, the uptake of 3H-estradiol per tissue weight was much higher than the uptake of hypothalumus and nearly equal to that of uterus in each day of age. The uptake of estradiol per whole tissue increased with age, but no for tissue weight (Exp. I, II).
3. In hypothalamus, the slight rise of counts per both whole tissues and tissue weight (Exp. II) was observed from 17 to 21 days.
4. In serum, a higher level of radioactivity was obtained at 17 days of age comparing with the levels of 21 and 25 days. Then, it is probable that the remarkable change in the metabolism of estrogen occures from 17 to 21 days of age.
