Localization, secretion, and action of inhibin in human placenta.
Inhibin is a gonadal glycoprotein hormone that regulates the production of follicle-stimulating hormone (FSH) by the anterior pituitary gland and exhibits intragonadal actions as well. The present study shows that inhibin-like immunoreactivity (inhibin-LI) is present in cells of the cytotrophoblast layer of human placenta at term and in primary cultures of human trophoblasts. Human chorionic gonadotropin (hCG) stimulated secretion of inhibin-LI from these cultured placental cells. This effect was mimicked by 8-bromo-cyclic adenosine monophosphate (8-bromo-cAMP), forskolin, and cholera toxin, suggesting that the mechanism of hCG induction of placental inhibin-LI secretion is cAMP-dependent. Incubation with an antiserum that binds the alpha-subunit of human inhibin increased the secretion of hCG and gonadotropin-releasing hormone-like immunoreactivity (GnRH-LI) from trophoblast cells in culture, suggesting a local tonic inhibitory action of endogenous inhibin on hCG and GnRH-LI release. The action of inhibin on hCG secretion may partially require the presence of placental GnRH, as suggested by evidence that a synthetic GnRH antagonist partially reverses the hCG increase induced by inhibin immunoneutralization. Results suggest paracrine roles for both inhibin and GnRH in the regulation of placental hCG production.
Petraglia
F
F
Sawchenko
P
P
Lim
A T
AT
Rivier
J
J
Vale
W
W
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D006063:Chorionic Gonadotropin / Q000378:metabolism* / Q000494:pharmacology; D002824:Chorionic Villi / Q000032:analysis; D005576:Colforsin / Q000494:pharmacology; D005246:Feedback; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007231:Infant, Newborn; D007265:Inhibins / Q000032:analysis / Q000502:physiology*; D008297:Male; D011247:Pregnancy; D012636:Secretory Rate / Q000187:drug effects; D014327:Trophoblasts / Q000032:analysis / Q000187:drug effects / Q000378:metabolism*
D006063:Chorionic Gonadotropin; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D007987:Gonadotropin-Releasing Hormone; D007265:Inhibins; D002772:Cholera Toxin