Multiple signal pathways coupling VIP and PACAP receptors to calcium channels in hamster submandibular ganglion neurons.
The Vasoactive intestinal polypeptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) are two novel neuropeptides which produce particular biological effects caused by interaction with G-protein-coupled receptors. We have shown in a previous study where VIP and PACAP 38 inhibit voltage-dependent calcium channel (VDCC) currents (ICa) via G-proteins in hamster submandibular ganglion (SMG) neurons. In this study, we attempt to further characterize the signal transduction pathways of VIP-and PACAP 38-induced modulation of ICa. Application of 1 microM VIP and PACAP 38 inhibited ICa by 33.0 +/- 3.1% and 36.8 +/- 2.6%, respectively (mean +/- S.E.M., n = 8). Application of strong voltage prepulse attenuated PACAP 38-induced inhibition of ICa. Pretreatment of cAMP dependent protein kinase (PKA) activator attenuated VIP-induced inhibition, but not the PACAP 38-induced inhibition. Intracellular dialysis of the PKA inhibitor attenuated the VIP-induced inhibition, but not the PACAP 38-induced inhibition. Pretreatment of protein kinase C (PKC) activator and inhibitor attenuated VIP-induced inhibition, but not the PACAP 38-induced inhibition. Pretreatment of cholera toxin (CTX) attenuated PACAP 38-induced inhibition of ICa. These findings indicate that there are multiple signaling pathways in VIP and PACAP 38-induced inhibitions of ICa: one pathway would be the VPAC1/VPAC2 receptors-induced inhibition involving both the PKA and PKC, and another one concerns the PAC1 receptor-induced inhibition via Gs-protein betagamma subunits. The VIP-and PACAP 38-induced facilitation of ICa can be observed in the SMG neurons in addition to inhibiting of ICa.
Kamaishi
Hideaki
H
Department of Physiology, Tokyo Dental College, 1-2-2, Masago, Mihama, Chiba 261-8502, Japan.
Endoh
Takayuki
T
Suzuki
Takashi
T
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002352:Carrier Proteins / Q000494:pharmacology; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005726:Ganglia, Parasympathetic / Q000166:cytology / Q000187:drug effects; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009479:Neuropeptides / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D011979:Receptors, Pituitary Hormone / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D013363:Submandibular Gland / Q000187:drug effects / Q000294:innervation; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism* / Q000494:pharmacology
D015220:Calcium Channels; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D051237:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I; D011979:Receptors, Pituitary Hormone; C015482:protein kinase modulator; D014660:Vasoactive Intestinal Peptide; D002772:Cholera Toxin; D011493:Protein Kinase C