The gonadotropin-releasing hormone associated peptide reduces calcium entry in prolactin-secreting cells.
The precursor molecule to the GnRH contains a peptide named GnRH-associated peptide (GAP) with PRL-inhibiting properties. In this work, we have studied the electrophysiological properties and responses to GAP of three different types of PRL-secreting cells: 1) the rat tumor cell line GH3, 2) normal rat pituitary cells in primary culture, and 3) human PRL-secreting adenoma cells. Using different but complementary techniques we show that GAP reduces intracellular Ca++ levels, [Ca++]i, and inhibits Ca++ transients in these cells. This reduction of [Ca++]i results from coordinate actions of GAP on K+ and Ca++ conductances and may explain the inhibitory effect of GAP on hormonal secretion by PRL-secreting cells.
Vacher
P
P
Laboratoire de Neurophysiologie, CNRS UA 1200, Université de Bordeaux II, France.
Mariot
P
P
Dufy-Barbe
L
L
Nikolics
K
K
Seeburg
P H
PH
Kerdelhue
B
B
Dufy
B
B
D000236:Adenoma / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D010911:Pituitary Neoplasms / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D011498:Protein Precursors / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000502:physiology
D011498:Protein Precursors; C050502:gonadotropin releasing hormone associated peptide; D007987:Gonadotropin-Releasing Hormone; D011388:Prolactin; D002118:Calcium