Analysis of progesterone receptor in the quail oviduct. Correlation between plasmatic estradiol and cytoplasmic progesterone receptor concentrations.
Specific binding sites for [3H]-progesterone are found in the cytosol fraction of the oviduct of castrated, immature and developing quails. The optimal conditions to accurately measure the total cytoplasmic concentration of this progesterone receptor are described. The dissociation constant (KD) at 0 degrees C is 3.6 +/- 0.6 x 10(-9) M (mean +/- SE) for [3H]-P and the concentration of binding sites is 13.4 +/- 2 pmol/mg DNA in immature animals. This binding capacity is not altered even 2 weeks after ovariectomy. During sexual development, although the dissociation constant remains unchanged, the number of binding sites increases to 74.5 +/- 1.6 pmol/mg DNA just before the beginning of the laying cycle. The concentration of cytoplasmic P receptor is under the inductive influence of estradiol. In castrated quails, estradiol 17 beta (E2) perfusion through the portal vein at a rate below or equal to 2 ng/min for 24 hr does not increase plasmatic E2 concentration and consequently does not change [3H]-P binding sites concentration in the oviduct. While E2 perfusion rate exceeds the metabolizing capacity of the liver (6.8 ng/min), both plasmatic E2 level and oviductal P receptor concentration are increased. When E2 is perfused through the jugular vein, plasmatic E2 level increases with the dose of E2 but P receptor concentration only increases when E2 perfusion rate reaches to 2.0 ng/min for 24 h.
D000818:Animals; D001667:Binding, Competitive; D002369:Castration; D003600:Cytosol / Q000378:metabolism; D004958:Estradiol / Q000097:blood*; D005260:Female; D010057:Oviducts / Q000378:metabolism*; D011374:Progesterone / Q000378:metabolism; D011784:Quail; D011980:Receptors, Progesterone / Q000378:metabolism*
D011980:Receptors, Progesterone; D011374:Progesterone; D004958:Estradiol