Proteins secreted by the sheep conceptus suppress induction of uterine prostaglandin F-2 alpha release by oestradiol and oxytocin.
In Exp. I, 0.5 mg oestradiol or vehicle (0.5 ml absolute ethanol + 0.5 ml 0.9% NaCl) was injected i.v. at 08:00 h on Day 14 (onset of oestrus = Day 0). Blood samples were obtained via a jugular catheter at 30 and 1 min before oestradiol and every 30 min for 10 h afterwards. Plasma was obtained and assayed for 15-keto-13,14-dihydro-PGF-2 alpha (PGFM) by radioimmunoassay. Before oestradiol, PGFM basal values were higher (P less than 0.01) in pregnant (N = 10) than nonpregnant (N = 6) ewes (193 +/- 30 vs 67 +/- 8 pg/ml). However, at 4-10 h after oestradiol, pregnant ewes (N = 5) had less variable (P less than 0.01) PGFM values than did nonpregnant ewes (N = 5). In Exp II, conceptus secretory proteins (CSP) were obtained by pooling medium from cultures of Day-16 sheep conceptuses (N = 40). Ewes received 750 micrograms CSP + 750 micrograms plasma protein (N = 6) or 1500 micrograms plasma protein (N = 6) per uterine horn at 08:00 h and 18:00 h on Days 12-14. All ewes received 0.5 mg oestradiol at 08:00 h on Day 14 and blood samples were collected as in Exp. I and assayed for PGFM. On Day 15, 3 ewes in each group received 10 i.u. oxytocin and 3 received saline i.v. at 08:00 h and blood samples were taken continuously from 10 min before to 60 min after treatment. Mean PGFM response to oestradiol was suppressed (P = 0.05) in CSP- vs plasma protein-treated ewes (371 +/- 129 vs 1188 +/- 139 pg/ml).(ABSTRACT TRUNCATED AT 250 WORDS)
Fincher
K B
KB
Bazer
F W
FW
Hansen
P J
PJ
Thatcher
W W
WW
Roberts
R M
RM
D000818:Animals; D015237:Dinoprost / Q000031:analogs & derivatives; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005326:Fetal Proteins / Q000502:physiology*; D010121:Oxytocin / Q000494:pharmacology*; D011247:Pregnancy; D011460:Prostaglandins F / Q000096:biosynthesis* / Q000097:blood; D012756:Sheep; D014599:Uterus / Q000187:drug effects / Q000378:metabolism*
D005326:Fetal Proteins; D011460:Prostaglandins F; C008228:15-keto-13,14-dihydroprostaglandin F2alpha; D004958:Estradiol; D010121:Oxytocin; D015237:Dinoprost