Estrogen, Progesterone, and the Blood-Uterine Lumen

To investigate whether the existence of the permeability barrier between blood and the uterine lumen in rats is dependent upon hormone treatment, the effects of estradiol (E) and progesterone (P) on the abilities of l HI sucrose, [14 Cl urea and tritiated water ([3 HI OH) to enter the uterine lumen from blood were determined in immature, ovariectomized rats following iv. injection of a radiolabeled test substance. To facilitate radioactivity recovery from the uterine lumen, intra-uterine saline injections were administered to all animals except those treated continuously with E only. In one series of experiments, animals were treated for 3 days with or without E (0.5 Mg/day) and P (2 mg/day) whereas, in another series, animals pretreated for 2 days with or without E (0.5 Mg/day) were treated on the following day with or without P (2 mg). In both series, animals were killed 15 or 60 mm after the i.v. injection. For [3 HI sucrose, the uterine fluid (UF) radio-activity concentrations did not change significantly with time and were significantly lower than those of serum at 15 mm postinjection in animals receiving any given hormone treatment. When [14 Cl urea was administered to animals treated continuously with E, the radioactivity concentra-tions either did not differ significantly between UF and serum or were significantly higher in UF. In animals receiving any other hormone treatment, UF radioactivity concentrations were signifi-cantly less than those of serum at 15 min postinjection, and whereas serum concentrations de-creased with time, those of UF increased. By contrast, [3 H] OH entered the uterine lumen readily, as indicated by radioactivity concentrations which were significantly higher in UF than in serum in all groups. The results of the present experiments suggest that a blood-uterine lumen permeability barrier to l H] sucrose exists independently of E and P and that the existence of a barrier to [14 CI urea is hormone dependent