Abstract
Summary
Ovariectomized rats received a single sc injection of 0, 0.25, 0.5 or 1.0 μg of estradiol-17β (E2) in 0.1 ml sesame oil or sc implants of osmotic minipumps delivering 1 or 2 μg E2/24 hr. Plasma levels of E2 were determined at 2, 4, 8 and 12 hr after injections or 3, 6, 12 and 24 hr after insertion of mini-pumps. Injections produced superphysiological levels of E2 in plasma by 2 hr, but E2 was depleted from plasma in less than 12 hr. Minipumps provided constant circulating concentrations of E2. Constant release methods provide a much more logical delivery system for estrogen suppression of gonadotropin than the use of an oil vehicle.
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