Temporal response of uterine prostaglandins to estradiol treatment in the ovariectomized-pregnant rat.
Previous studies in our laboratory have shown that 24 hours of estradiol treatment significantly enhanced uterine prostaglandin (PG)F, PGE and thromboxane B2 (TxB2) levels but had no effect on 6-Keto-PGF1 alpha (6KF) concentrations in ovariectomized-pregnant rats. One explanation for the lack of an augmentation in 6KF was a temporal difference in response (i.e. 6KF increased and decreased within the 24 hour period). To test this possibility rats were ovariectomized on day 19 of pregnancy and sacrificed 0, 4, 8, 12, 16, 20 and 24 hours after estradiol treatment. Uterine tissue and venous plasma were analyzed for PGs by radioimmunoassay. No significant (p greater than .05) alterations were detected for any of the uterine PGs at 0, 4, 8 and 12 hours. However, at 16 hours PGF, TxB2 and PGE all showed significant (p less than .05) increases (2.4, 3.4 and 2.1 fold, respectively) compared to 12 hours. In contrast, no significant augmentation in 6KF levels (p greater than .05, 1.3 fold) was detected at 16 compared to 12 hours although it was enhanced relative to 0 and 4 hours. In addition, PGF, TxB2 and PGE, but not 6KF, showed further increases 24 hours after estradiol administration. No alterations were found (p greater than .05) for any of the PGs in uterine venous plasma at the time points studied. In summary, uterine PGF, PGE and TxB2 net production appears to be more enhanced by estradiol treatment than 6KF at the time points studied. In addition, there is a slight, but significant, difference in the temporal response characteristics of 6KF compared to the other PGs.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D002369:Castration; D004958:Estradiol / Q000097:blood / Q000494:pharmacology*; D005260:Female; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011453:Prostaglandins / Q000378:metabolism*; D011458:Prostaglandins E / Q000378:metabolism; D011460:Prostaglandins F / Q000378:metabolism; D051381:Rats; D013929:Thromboxane B2 / Q000378:metabolism; D014599:Uterus / Q000187:drug effects / Q000378:metabolism*
D011453:Prostaglandins; D011458:Prostaglandins E; D011460:Prostaglandins F; D011374:Progesterone; D004958:Estradiol; D013929:Thromboxane B2