Fetal and maternal endocrine changes approaching parturition in the goat: lack of evidence for prostaglandins E2 and F2alpha as signals for luteolysis.
We investigated the temporal relationship of fetal cortisol secretion to circulating concentrations of fetal ACTH1-39 and its high-molecular weight precursors in goats. We also measured the concentrations of progesterone, estradiol-17beta estrone sulfate, prostaglandin (PG) E, PGF2alpha, and PGF2alpha metabolite (PGFM) in maternal arterial plasma over the last month of gestation. Prostaglandin concentrations were also measured in utero-ovarian venous plasma. There was a positive association between ACTH1-39 in fetal plasma and the prepartum surge in fetal cortisol that commenced 8 days before labor. The fetal cortisol surge was followed by a simultaneous decrease in maternal progesterone and an increase in plasma estrogens commencing 3-4 days before labor. No change in basal prostaglandin concentration occurred before this time. There was a positive veno-arterial difference of PGE and PGF2alpha across the uterine vascular bed, confirming the uteroplacental unit as a major source of these eicosanoids in the plasma of the pregnant doe. We conclude that the fetal signal for parturition precedes luteolysis by some 5 days and find no evidence of changes in the basal concentrations of PGE and PGF2alpha in maternal plasma at the time of luteolysis.
Ford
M M
MM
Department of Physiology, Monash University, Clayton, Victoria, Australia.
Young
I R
IR
Caddy
D J
DJ
Thorburn
G D
GD
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D003338:Corpus Luteum / Q000502:physiology*; D015237:Dinoprost / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism*; D004967:Estrogens / Q000097:blood; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005333:Fetus / Q000378:metabolism*; D006041:Goats / Q000502:physiology*; D006854:Hydrocortisone / Q000097:blood; D007743:Labor, Obstetric; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011453:Prostaglandins / Q000097:blood / Q000378:metabolism; D011458:Prostaglandins E / Q000097:blood; D011498:Protein Precursors / Q000097:blood; D015398:Signal Transduction; D014599:Uterus / Q000378:metabolism
D004967:Estrogens; D011453:Prostaglandins; D011458:Prostaglandins E; D011498:Protein Precursors; D011374:Progesterone; D000324:Adrenocorticotropic Hormone; D015237:Dinoprost; D015232:Dinoprostone; D006854:Hydrocortisone