Pituitary adenylate cyclase activating polypeptide (PACAP) increases cytosolic-free calcium concentration in folliculo-stellate cells and somatotropes of rat pituitary.
Pituitary adenylate cyclase activating polypeptide (PACAP) is a new member of the secretin/VIP peptide family. In order to identify pituitary target cells for PACAP, we examined the effect of PACAP on the cytosolic-free Ca2+ concentrations, [Ca2+]i, in cells using Fura-2 and a digital imaging system. In a concentration-dependent manner, PACAP increased [Ca2+]i in pituitary cells, from 10(-11) to 10(-8) M. Some cells responded to PACAP at 10(-11) M, while others only at 10(-8) M, showing a diversity among cells in the sensitivity to PACAP. Both PACAP and growth hormone-releasing factor (GRF) at 10(-8) M increased [Ca2+]i in 25% and 33% of the total pituitary cells, respectively. About 38% of the GRF-responsive cells also responded to PACAP. Some of the cells that responded to PACAP were immunocytochemically identified as growth hormone (GH) cells or folliculo-stellate (FS) cells using antisera against GH or S-100 protein, respectively. The results indicate that both the folliculo-stellate cells and GH cells of the pituitary are the direct targets for PACAP, but the possibility that other cell types also respond to PACAP cannot be excluded.
Yada
T
T
Department of Physiology, Kagoshima University School of Medicine, Japan.
Vigh
S
S
Arimura
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D005260:Female; D013006:Growth Hormone / Q000378:metabolism; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology; D066298:In Vitro Techniques; D009479:Neuropeptides / Q000494:pharmacology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
C495403:Adcyap1 protein, rat; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; D011188:Potassium; D002118:Calcium