EFFECTS OF EXOGENOUS PROGESTERONE AND ESTRADIOL ON PROSTAGLANDIN-F AND 13,14-DIHYDRO-15-OXO PROSTAGLANDIN-F2ALPHA CONCENTRATIONS IN UTERI AND PLASMA OF OVARIECTOMIZED EWES

: The effects of progesterone and estradiol administration on plasma and uterine concentrations of prostaglandin F2alpha (PGF2a) and 13,14-dihydro-15-oxo PGF (PGFM) were studied in ovariectomized ewes. Treatment with 30 mcg/day estradiol for 9 days did not alter the concentration of PGF2a in uterine caruncles and intercaruncular tissue, the release of PGF2a or PGFM from these tissues in vitro, or the concentrations of PGF2a in the utero-ovarian vein or PGFM in the jugular vein. Nonetheless, there was an accumulation of estradiol in uterine tissue. Treatment with 20 mg/day progesterone for 9 days resulted in a significant (p less than .01) increase in PGF2a concentration in the uterine caruncles, a significant (p less than .01) increase in the release of PGF2a from caruncles incubated in the presence of arachidonic acid, and an increase in the concentration of PGFM in the jugular vein. The administration of estradiol to animals pretreated with progesterone further increased the PGF content of uterine caruncles, the release of PGF2a into the utero-ovarian vein, and the concentration of PGFM in the jugular vein. The amount of PGF2a in the caruncles was significantly (p less than .05) greater than that in the intercaruncular area, and the amount of PGF2a and PGFM released in vitro was also greater in the caruncles. Animals treated with progesterone plus estradiol showed a good correlation between PGF2a concentrations in blood samples obtained at the same time from the right and left utero-ovarian vains, and all animals showed a high correlation between utero-ovarian PGF2a and peripheral PGFM concentrations. Lipid droplets were also more predominant in the caruncular epithelium of progesterone-treated animals than in other groups. The results demonstrate the necessary presence of progesterone for the activation of prostaglandin synthetase activity and the promotion of PGF2a production.