Effect of Prostaglandin F2α-Induced Luteolysis on In Vivo and In Vitro Progesterone Production by Individual Placentomes of Cows1

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Abstract
This study investigated placental progesterone production by bovine placentomes. Catheters were placed in the femoral artery (FA) and in the caruncular artery (CA), caruncular vein (CV) and lymphatic vessel of a prominent placentome of 13 cows at 200 d of gestation. Four of the 13 cows were given prostaglandin F2α (PGF2α) after surgery, and blood and lymph were collected for progesterone determination. After 24 h, progesterone was higher (P<.01) in FA and CA plasma from control cows that FA and CA plasma from PGF2α-treated cows (5.11 ± .29 and 5.17 ± .64 vs 1.41 ± .08 and 1.15 ± .08 ng/ml, respectively), but CV concentrations were similar (3.38 ± .30 vs 2.56 ± .24, respectively). There was a net uptake of progesterone by placentomes from control cows (P<.01) but a net secretion in PGF2α-treated cows (P<.05). Lymph contained low progesterone concentrations regardless of treatment. Cows were slaughtered at 240 d of gestation. Placentomes were removed and perfused with pregnenolone through the maternal and fetal arteries. Fetal venous effluent contained more progesterone than maternal venous effluent (P<.001) in both groups, and fetal venous effluent of placentomes from PGF2α-treated cows contained more progesterone than that from control cows (P<.05). Maternal and fetal components of other placentomes were cultured alone or in co-culture along with pregnenolone and (or) epostane. Fetal tissue produced more progesterone (P<.001) than maternal tissue when each was cultured alone, but fetal tissue production declined when co-cultured with maternal tissue. Tissue from PGF2α-treated cows produced more progesterone than tissue from control cows (P<.05). These data suggest that the bovine placenta can produce progesterone but that the corpus luteum of pregnancy may inhibit production under normal circumstances. Copyright © 1987. American Society of Animal Science . Copyright 1987 by American Society of Animal Science