Abstract
Summary
In vitro and in vivo uptake and fecal and urinary excretion of radioactive estradiol were determined in normally cycling rats fed a high-fat diet ad libitum or restricted or a grain diet ad libitum starting at 3 wk of age. At 29 wk of age, in vitro uptake of estradiol by parametric adipose tissue was not influenced by dietary treatment. However, at 41 wk of age, uptake per 100 mg of parametric or mesenteric adipose tissues was significantly less for high-fat fed rats than for grain-fed rats. In vivo uptake of injected estradiol-4-14C was highest in the high-fat ad libitum rats followed by high-fat restricted and grain-fed rats. This differential uptake was due mainly to an increased adipose tissue size in the high-fat fed rats which were obese. Specific activities of tissues were not responsible for the different uptake. However, specific activities of tissue varied depending on the tissue examined. Thus, the mesenteric adipose tissue had the highest and the inguinal plus genital adipose tissue was the lowest. Total excretion of radioactivity was not different among the 3 dietary groups but the route as well as the proportion in the feces and urine varied significantly during the first 2–3 days after the injection of radioactive estradiol.
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