title: Trophoblastin, an antiluteolytic protein present in early pregnancy in sheep.
abstract: Trophoblastin, an antiluteolytic component from the embryo, was identified in the ewe by the means of intrauterine injections of homogenates from trophoblasts at 14--16 days pregnancy. Homogenates from embryos and their membranes at 21--23 days pregnancy did not extend the life of the corpus luteum, suggesting that trophoblastin synthesis occurs for only a short period. The trophoblastin was thermolabile (80 degrees C for 30 min) and inactivated by pronase. Treatment of ewes with oCS, hCG, and extracts of 120-day placentae did not affect the time of luteolysis. The protein appears to be insoluble at pH 7 or 8, but to dissolve readily at pH 9.6. After injection of homogenates or extracts from 15--16-day-old trophoblasts, the initial CL were maintained for more than 1 month in most cyclic recipient ewes. Surgical removal of embryos at 21--23 days resulted in luteal maintenace for more than 1 month in over 50% of the operated animals. All the maintained CL were secretory although their average weight was about one-half of that CL of normal pregnancy, suggesting the existence of complementary luteotrophic placental factors. The uteri of most of these pseudopregnant ewes were distended with a clear, sterile fluid.
mesh_terms: D000818:Animals; D003338:Corpus Luteum / Q000187:drug effects; D005260:Female; D007370:Interferon Type I; D008186:Luteolytic Agents / Q000037:antagonists & inhibitors*; D011247:Pregnancy; D011257:Pregnancy Proteins; D011270:Pregnancy, Animal; D011374:Progesterone / Q000097:blood; D014176:Protein Biosynthesis; D011506:Proteins / Q000032:analysis* / Q000494:pharmacology; D012756:Sheep / Q000196:embryology*; D013997:Time Factors; D014327:Trophoblasts / Q000032:analysis
chemical_list: D007370:Interferon Type I; D008186:Luteolytic Agents; D011257:Pregnancy Proteins; D011506:Proteins; C020947:interferon tau; D011374:Progesterone