PACAP and VIP stimulate Ca2+ oscillations in rat gonadotrophs through the PACAP/VIP type 1 receptor (PVR1) linked to a pertussis toxin-insensitive G-protein and the activation of phospholipase C-beta.
Pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) are hypothalamic factors that play roles in the regulation of anterior pituitary cell activity. PACAP exists in 2 forms physiologically, a 38 amino acid form (PACAP38) and a form possessing the N-terminal 27 amino acids of PACAP38 (PACAP27). We have previously shown that PACAP38 stimulates an increase in [Ca2+]i in rat gonadotrophs. In an attempt to identify the PACAP receptor type underlying this effect, we compared the potency of PACAP38, PACAP27 and VIP to stimulate Ca2+ changes in identified single rat gonadotrophs. All 3 peptides at 100 nM were capable of stimulating high amplitude Ca2+ oscillations, which were also observed in the absence of extracellular Ca2+. The order of potency of these peptides was PACAP38 > PACAP27 > VIP, and a potent antagonist of the PACAP/VIP type II binding site ([4-CI-D-Phe6, Leu17]-VIP) failed to block these responses, suggesting that these effects are mediated through a PACAP/VIP type 1 receptor (PVR1). The Ca2+ responses to PACAP38 and VIP were unaffected by overnight treatment of the cells with pertussis toxin (PTX; 250 ng/ml) indicating that these responses are mediated by a PTX-insensitive G-protein. Finally, the Ca2+ responses stimulated by PACAP38 and VIP were blocked by the phospholipase C-beta blocker U73122 (5 microM). In summary, PACAP stimulates Ca2+ oscillations in rat gonadotrophs through the activation of the PVR1 linked to a PTX-insensitive G-protein and the activation of phospholipase C-beta. VIP can stimulate the same pathway in rat gonadotrophs, although it is at least 100 fold less potent than PACAP38.
Hezareh
M
M
Fondation pour Recherches Médicales, University of Geneva, Switzerland.
Schlegel
W
W
Rawlings
S R
SR
D037361:Adenylate Cyclase Toxin; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology; D003470:Culture Media / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005456:Fluorescent Dyes; D019204:GTP-Binding Proteins / Q000502:physiology*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009479:Neuropeptides / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D010507:Periodicity; D037342:Pertussis Toxin; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D054799:Phospholipase C beta; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D011979:Receptors, Pituitary Hormone / Q000502:physiology*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
C495403:Adcyap1 protein, rat; D037361:Adenylate Cyclase Toxin; D003470:Culture Media; D004963:Estrenes; D005456:Fluorescent Dyes; D007527:Isoenzymes; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D010726:Phosphodiesterase Inhibitors; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011760:Pyrrolidinones; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D011979:Receptors, Pituitary Hormone; D010566:Virulence Factors, Bordetella; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D014660:Vasoactive Intestinal Peptide; D037342:Pertussis Toxin; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D019204:GTP-Binding Proteins; D002118:Calcium