Pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates endozepine release from cultured rat astrocytes via a PKA-dependent mechanism.
Astroglial cells synthesize and release endozepines, neuropeptides that are related to the octadecaneuropeptide ODN. Glial cells also express PACAP/VIP receptors. We have investigated the possible effect of PACAP on the release of ODN-like immunoreactivity (ODN-LI) by cultured rat astrocytes. Administration of PACAP27 and PACAP38 induced a concentration-dependent increase in secretion of ODN-LI whereas VIP was approximately 1000-fold less potent. The maximum effect of PACAP38 occurred after 5 min, then gradually declined during the next 10 min. The stimulatory effects of PACAP and VIP were abrogated by the PACAP antagonist PACAP6-38. PACAP38 stimulated cAMP formation, activated polyphosphoinositide turnover, and provoked calcium mobilization from IP3-sensitive pools. The PKA inhibitor H89 suppressed PACAP-induced secretion of ODN-LI, whereas PLC inhibitor U73122 and the PKC inhibitor chelerythrine had no effect. In contrast, U73122 restored the stimulatory action of PACAP on ODN-LI release and cAMP formation during prolonged (15 min) incubation with the peptide, and this effect was prevented by PMA. The present results demonstrate that PACAP stimulates endozepine release through activation of PAC1 receptors coupled to the AC/PKA pathway. Our data also show that activation of the PLC/PKC pathway down-regulates the effect of PACAP on endozepine release.
Masmoudi
Olfa
O
European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U413, UA CNRS, University of Rouen, 76821 Mont-Saint-Aignan, France.
Gandolfo
Pierrick
P
Leprince
Jerome
J
Vaudry
David
D
Fournier
Alain
A
Patte-Mensah
Christine
C
Vaudry
Hubert
H
Tonon
Marie-Christine
MC
D000818:Animals; D001253:Astrocytes / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism*; D002118:Calcium / Q000032:analysis; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D026261:Diazepam Binding Inhibitor / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D007700:Kinetics; D009479:Neuropeptides / Q000378:metabolism / Q000494:pharmacology*; D010446:Peptide Fragments; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051381:Rats; D015398:Signal Transduction
C495403:Adcyap1 protein, rat; D026261:Diazepam Binding Inhibitor; D009479:Neuropeptides; D010446:Peptide Fragments; D018129:Phosphatidylinositol Phosphates; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; C067529:diazepam binding inhibitor (33-50); D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium