Involvement of the adenylyl cyclase/protein kinase A signaling pathway in the stimulatory effect of PACAP on frog adrenocortical cells.
We have previously shown that PACAP stimulates in vitro the secretion of corticosteroids by frog adrenal explants and that PACAP increases cAMP formation and cytosolic calcium concentration ('Ca2+'i) in adrenocortical cells. The aim of the present study was to investigate the involvement of cAMP and 'Ca2+'i in the stimulatory effect of PACAP on steroid production. Incubation of adrenal explants with PACAP resulted in a significant increase in total inositol phosphate formation. Administration of the protein kinase A inhibitor, H89, markedly reduced the stimulatory effect of PACAP on corticosterone and aldosterone secretion by perifused adrenal slices. In contrast, chelation of intracellular or extracellular calcium, or incubation with calcium channel blockers, had no effect on PACAP-evoked steroid secretion. Incubation of the cells with BAPTA or thapsigargin totally suppressed the stimulatory effect of PACAP on 'Ca2+'i. In contrast, suppression of extracellular calcium with EGTA or blockage of voltage-dependent Ca2+ channels did not impair PACAP-induced Ca2+ response. These data indicate that, in frog adrenocortical cells, the stimulatory effect of PACAP on steroid secretion is mediated through activation of the cAMP/PKA pathway. Concurrently, PACAP causes calcium mobilization from IP(3)-dependent intracellular stores through activation of a phospholipase C, while the calcium response is not involved in the stimulatory effect of PACAP on corticosteroid secretion.
Montero-Hadjadje
Maite
M
INSERM U413, European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, University of Rouen, 76821 Mont-Saint-Aignan, France.
Delarue
Catherine
C
Fournier
Alain
A
Vaudry
Hubert
H
Yon
Laurent
L
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000302:Adrenal Cortex / Q000187:drug effects* / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D017610:Calcium Compounds / Q000494:pharmacology; D002478:Cells, Cultured; D002704:Chlorates / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007295:Inositol Phosphates / Q000096:biosynthesis; D007546:Isoquinolines / Q000494:pharmacology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011893:Rana esculenta / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D013256:Steroids / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology
D002121:Calcium Channel Blockers; D017610:Calcium Compounds; D002704:Chlorates; D007295:Inositol Phosphates; D007546:Isoquinolines; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D047428:Protein Kinase Inhibitors; D013256:Steroids; D013449:Sulfonamides; C091366:calcium chlorate; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D002118:Calcium