Response of the @entity19 uterus to XXXX stimulation: agonism and antagonism.

@entity172 @entity19 @entity1184 @entity1373 @entity53 @entity7034 @entity38036
@entity38036 ( @entity7034 ) acts as an @entity172 agonist or antagonist depending on the animal model used. In the CD-1 @entity19 uterus, a three-day uterine bioassay of @entity7034 produced a bell-shaped dose response curve with a maximal uterine wet weight increase at 200 micrograms/kg; this dose produced only a fractional increase in uterine dry weight. Combination treatment with @entity7034 and @entity53 antagonized @entity53 stimulation of both wet and dry weight parameters. The time course of uterine wet weight stimulation following a single injection of @entity7034 had an early pattern (0-10 h) similar to that of @entity53 . However, at later times after stimulation, the patterns changed dramatically: the low @entity7034 dose (200 micrograms/kg) returned to control levels by 24 h; @entity53 and the high dose @entity7034 (1.7 mg/kg) showed sustained stimulation, which peaked at 36 h with @entity7034 compared to 24 h for @entity53 . Nuclear @entity172 receptor (ER) levels were measured after a single injection of 1.7 mg/kg @entity7034 and showed a bimodal pattern similar to that seen with @entity53 , with increases at 1 h and 8 h, although the overall ER levels were elevated above those seen with @entity53 . Cytosolic ER levels with @entity7034 decreased by 1 h and remained low up to 48 h. @entity7034 treatment did stimulate uterine DNA and RNA synthesis, with a delayed time course compared to @entity53 . DNA synthesis following a single 1.7 mg/kg dose of @entity7034 was 2.5 times higher than that produced by 20 micrograms/kg @entity53 . @entity7034 treatment resulted in @entity1184 and @entity1373 in the luminal epithelium but not in the glandular epithelium. Long-term exposure to @entity53 for 5 wk resulted in development of uterine @entity1373 and increased secretory activity; long-term exposure to @entity7034 produced a more significant tissue @entity1373 but no secretions. These studies show that @entity7034 stimulates some of the receptor-mediated responses attributed to an @entity172 agonist in the @entity19 uterus; but, when co-administered with @entity53 , @entity7034 antagonizes some aspects of @entity172 action.
