Influence of Estradiol Benzoate on Fat Storage. ∗

Abstract

In a recent study Loeb and Burr¹ showed that female rats store more body fat than males when maintained on a diet rich in saturated fat (hydrogenated coconut oil) but devoid of essential fatty acids. It then became a matter of interest to ascertain whether this finding could be attributed to the effect of estrogen on fat metabolism. Zondek and Marx² reported that estrogen not only induced a marked lipemia in fowl but also caused the accumulation of fat in the internal organs, particularly the liver. However, their findings with mammals were negative. Loeb³ observed a definite, though moderate, lipemia in male rats fed a high fat diet lacking in essential fatty acids when estradiol benzoate was injected over a 4-week period. The present report is concerned with the storage of body fat under similar conditions.

Methods. Albino rats of the Wistar strain were taken at weaning time and placed on a low fat diet for 4 weeks to deplete the fat reserve. During the next 8 weeks, which comprised the experimental period, the animals were maintained on diet 580-B, a ration rich in saturated fat-71% hydrogenated coconut oil. One group received, subcutaneously, 3 large doses of estradiol benzonate† (100μg per dose), on alternate days, during the last week of the experimental period. Two other groups were given 24 more moderate doses (30μg and 5μ, re-spectively), daily except Sunday, throughout the last 4 weeks of the experimental period.³ The animals were sacrifices by etherization and the carcases† analyzed for total fat by digestion with 28j% KOH in 50% alcohol for 4 hr followed by petroleum ether extraction of acidified aliquot portions.