Increased concentrations of 17alpha, 20alpha-dihydroxypregn-4-en-3-one in maternal and foetal plasma near parturition in sheep.
Using specific radioimmunoassays, 17alpha,20alpha-dihydroxypregn-4-en-3-one and progesterone were measured in maternal utero-ovarian venous plasma from four sheep during parturition induced with dexamethasone and two sheep at spontaneous delivery. 17alpha,20alpha-Dihydroxypregn-4-en-3-one was also measured in maternal jugular venous and foetal posterior vena caval plasma from one dexamethasone-induced animal over the same period. Basal utero-ovarian venous levels of 17alpha,20alpha-dihydroxypregn-4-en-3-one were in the range 3-7 ng/ml; at the time of the pre-labour fall in maternal progesterone, the concentration of 17alpha-20alpha-dihydroxypregn-4-en-3-one increased, reaching 17-76 ng/ml at delivery. Maternal levels fell rapidly after delivery. In contrast to foetal progesterone concentrations, which are low, foetal 17alpha,20alpha-dihydroxypregn-4-en-3-one levels were approximately the same as those in the maternal utero-ovarian vein. Maternal jugular venous levels in one animal were 50-80% of those in the utero-ovarian vein. These findings confirm earlier results obtained in vitro which indicated that exposure to glucocorticoid results in increased activity of a steroid 17alpha-hydroxylase in the ovine foetal placenta.
D006907:17-alpha-Hydroxypregnenolone / Q000031:analogs & derivatives* / Q000097:blood; D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D007751:Labor, Induced; D007743:Labor, Obstetric; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011863:Radioimmunoassay; D012756:Sheep; D013997:Time Factors
D006907:17-alpha-Hydroxypregnenolone; D011374:Progesterone; D003907:Dexamethasone