Paracrine control of gonadotrophs.
There is increasing evidence for communication among pituitary cells. Hormone-producing pituitary cells may communicate with each other and with folliculostellate cells. The latter cells surround pituitary hormone-producing cells and are connected by tight junctions to form a network that allows for their coordinated function. Folliculostellate cells are targets of cytokines, peptides, and steroid hormones, and produce growth factors and cytokines, including follistatin, the dynamic regulator of follicle-stimulating hormone (FSH) production that binds activin, and limits activin signaling. Pituitary adenylate cyclase-activating peptide (PACAP) and its receptor are found in folliculostellate cells in which they stimulate transcription of the follistatin gene through cyclic adenosine monophosphate/protein kinase A (PKA) signaling. When PACAP increases, follistatin levels increase, and FSH-beta mRNA is reduced. PACAP also activates gonadotrophs to stimulate transcription of the gonadotropin alpha-subunit gene and lengthen the LH-beta mRNA, presumably to prolong it half-life, and increases responsiveness to GnRH. Accordingly, PACAP differentially regulates FSH and LH, and may prove to be a key player in reproduction through a novel paracrine mechanism.
Winters
Stephen J
SJ
Division of Endocrinology, Metabolism and Diabetes, University of Louisville School of Medicine, 550 Jackson Street, Louisville, KY 40202, USA. sjwint01@louisville.edu
Moore
Joseph P
JP
D028341:Activins / Q000378:metabolism; D000818:Animals; D005640:Follicle Stimulating Hormone / Q000235:genetics / Q000378:metabolism*; D038681:Follistatin / Q000378:metabolism; D052681:Gonadotrophs / Q000378:metabolism*; D006801:Humans; D007265:Inhibins / Q000378:metabolism; D007986:Luteinizing Hormone / Q000235:genetics / Q000378:metabolism*; D019899:Paracrine Communication; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000378:metabolism*; D012098:Reproduction / Q000502:physiology*; D015398:Signal Transduction; D019108:Tight Junctions / Q000378:metabolism; D014158:Transcription, Genetic
D038681:Follistatin; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D028341:Activins; D007265:Inhibins; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone