| Abstract: | At the time of the experiment, lean animals weighed 226-235 gm and the fatty rats 330-440 gm. On Day 5 after castration, rats received injections of estradiol-17beta (E2) for a 3-day period. Doses were .01-100 mcg/100 gm of body weight. Radioiodine uptake was determined by injecting 50 microCi of iodine-125 ip 24 hours before sacrifice. Beginning 12 hours after the last dose of E2, pairs of rats including a fatty and lean rat were sacrificed until all had been killed. Ovaries (at castration or autopsy), pituitary, and thyroid were removed and weighed. Uteri in obese rats were significantly smaller than in lean rats. There was a close dose-response relationship between E2 and the weight of the uteri; this was more marked in the obese rats. The radioactivity of the thyroid was increased more in the lean rats. Fatty rats ate more food than lean rats. The highest dose of E2 did not increase the food intake of obese rats but did increase that of the lean animals. It is concluded that the small uteri in the fatty rats may be due to decreased estrogenization and that this may also partly account for the small pituitary and low thyroid uptake of radioiodine. |
