In vivo levels of prostaglandin F2 alpha, E2 and prostacyclin in the corpus luteum of pregnant and pseudopregnant rats.
Prostaglandin F2 alpha (PGF2 alpha) is a well-known luteolytic factor in the rat corpus luteum. To investigate a possible luteal origin of PGF2 alpha, measurements of this prostaglandin were performed in different luteal tissues in vivo. Prostaglandin E2 (PGE2) and the stable metabolite of prostacyclin, 6-keto-PGF1 alpha, were assayed simultaneously. Corpora lutea of different ages from 57 pregnant and pseudopregnant rats (mated with sterile males) were rapidly excised, dissected in 0 degree C indomethacin solution, homogenized, and extracted for prostaglandins with solid-phase extraction cartridges. Prostaglandins were determined by radioimmunoassay. Plasma levels of progesterone and 20 alpha-dihydroprogesterone were also monitored. In the adult pseudopregnant rat model, luteolysis occurs at Day 13 +/- 1, and maximal levels of all three prostaglandins were detected on Day 13 of pseudopregnancy: 0.40 +/- 0.02, 2.6 +/- 0.29, and 1.76 +/- 0.24 pmol/mg protein (mean +/- SEM, n=7) for PGF2 alpha, PGE2, and 6-keto-PGF1 alpha respectively. In pregnant rats, on the corresponding day, levels were considerably lower: 0.15 +/- 0.02, 0.90 +/- 0.13, and 0.50 +/- 0.06 pmol/mg protein (mean +/- SEM, n=9, p less than 0.0001), respectively. Luteal levels in pregnant rats showed a continuous decline on Days 13 and 19 for all prostaglandins measured, whereas in pseudopregnant rats an increment of PGF2 alpha was noted between Days 7 and 13 and remained high on Day 19. PGE2 closely followed levels of PGF2 alpha, but at a 5- to 10-fold higher level. The coefficient of correlation between PGF2 alpha and PGE2 in the luteal compartment of both models was 0.87 (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
Olofsson
J
J
Department of Physiology, University of Umeå, Sweden.
Norjavaara
E
E
Selstam
G
G
D015121:6-Ketoprostaglandin F1 alpha / Q000378:metabolism*; D000818:Animals; D003338:Corpus Luteum / Q000378:metabolism*; D015237:Dinoprost / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism*; D005260:Female; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D011555:Pseudopregnancy / Q000378:metabolism*; D051381:Rats
D015121:6-Ketoprostaglandin F1 alpha; D015237:Dinoprost; D015232:Dinoprostone