title: Adrenocorticotropic activity of an extract from sheep placental tissue at term.
abstract: We have performed experiments to determine possible adrenocorticotropic activity in placental tissue of a sheep at term. The placental tissue was homogenized and extracted with 0.1 mmol/L of ammonium bicarbonate. The adrenocorticotropic activity of the term placental extract was compared to that of the vehicle (saline solution) and synthetic adrenocorticotropic hormone (ACTH). A single bolus injection of term placental extract had no significant effect on the plasma concentration of cortisol or progesterone. In a separate protocol, a bolus injection of ACTH was administered before and after a 48-hour continuous infusion of term placental extract, ACTH, or saline solution. The infusion of term placental extract or ACTH caused a significant increase in the basal cortisol and progesterone concentrations and a greater progesterone response following the second ACTH bolus. In vitro, the isolated adrenal cells from the term placental extract- and ACTH-infused animals showed a significantly greater ability to produce cortisol in the presence of exogenous substrate and ACTH. We concluded that placental tissue from sheep at term contains a substance which, when infused in vivo, has a corticotropic effect on the adrenal glands.
mesh_terms: D000311:Adrenal Glands / Q000033:anatomy & histology / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000032:analysis / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D005260:Female; D006854:Hydrocortisone / Q000096:biosynthesis* / Q000097:blood; D009929:Organ Size; D010920:Placenta / Q000032:analysis / Q000502:physiology*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011863:Radioimmunoassay; D012756:Sheep; D014020:Tissue Extracts / Q000494:pharmacology*
chemical_list: D014020:Tissue Extracts; D011374:Progesterone; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone