title: Stimulatory effect of pituitary adenylate cyclase-activating polypeptide 6-38, M65 and vasoactive intestinal polypeptide 6-28 on trigeminal sensory neurons.
abstract: Pituitary adenylate cyclase-activating polypeptide (PACAP) acts on G protein-coupled receptors: the specific PAC1 and VPAC1/VPAC2 receptors. PACAP6-38 was described as a potent PAC1/VPAC2 antagonist in several models, but recent studies reported its agonistic behaviors proposing novel receptorial mechanisms. Since PACAP in migraine is an important research tool, we investigated the effect of PACAP and its peptide fragments on trigeminal primary sensory neurons. Effect of the peptides was studied with ratiometric Ca-imaging technique using the fluorescent indicator fura-2 AM on primary cultures of rat and mouse trigeminal ganglia (TRGs) neurons. Specificity testing was performed on PAC1, VPAC1 and VPAC2 receptor-expressing cell lines with both fluorescent and radioactive Ca-uptake methods. Slowly increasing intracellular free calcium concentration [Ca(2+)]i was detected after PACAP1-38, PACAP1-27, vasoactive intestinal polypeptide (VIP) and the selective PAC1 receptor agonist maxadilan administration on TRG neurons, but interestingly, PACAP6-38, VIP6-28 and the PAC1 receptor antagonist M65 also caused similar activation. The VPAC2 receptor agonist BAY 55-9837 induced similar activation, while the VPAC1 receptor agonist Ala(11,22,28)VIP had no significant effect on [Ca(2+)]i. It was proven that the Ca(2+)-influx originated from intracellular stores using radioactive calcium-45 uptake experiment and Ca-free solution. On the specific receptor-expressing cell lines the antagonists inhibited the stimulating actions of the respective agonists, but had no effects by themselves. PACAP6-38, M65 and VIP6-28, which were described as antagonists in numerous studies in several model systems, act as agonists on TRG primary sensory neurons. Currently unknown receptors or splice variants linked to distinct signal transduction pathways might explain these differences.
authors: Department of Pharmacology and Pharmacotherapy, MTA-PTE Chronic Pain Research Group, Szentágothai Research Center, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary. Electronic address: saghyeva@gmail.com.
authors: É
authors: É
authors: Sághy
authors: Department of Pharmacology and Pharmacotherapy, MTA-PTE Chronic Pain Research Group, Szentágothai Research Center, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary. Electronic address: payrits.maja@gmail.com.
authors: M
authors: M
authors: Payrits
authors: Department of Pharmacology and Pharmacotherapy, MTA-PTE Chronic Pain Research Group, Szentágothai Research Center, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary. Electronic address: zsuzsanna.helyes@aok.pte.hu.
authors: Zs
authors: Z
authors: Helyes
authors: Department of Anatomy, MTA-PTE "Lendület" PACAP Research Team, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary. Electronic address: dora.reglodi@aok.pte.hu.
authors: D
authors: D
authors: Reglődi
authors: Department of Anatomy, MTA-PTE "Lendület" PACAP Research Team, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary. Electronic address: bankieszti@gmail.com.
authors: E
authors: E
authors: Bánki
authors: Department of Medical Chemistry, University of Szeged, Szeged-6720, Dugonics Street 13, Hungary. Electronic address: toth.gabor@med.u-szeged.hu.
authors: G
authors: G
authors: Tóth
authors: UMR 1149 INSERM/Centre de Recherche sur l'Inflammation, Université Paris Diderot, Faculte de Medecine Paris 7 - Site Bichat, 16 Rue Henri Huchard, 75890 Paris Cedex 18, France. Electronic address: alain.couvineau@inserm.fr.
authors: A
authors: A
authors: Couvineau
authors: Department of Pharmacology and Pharmacotherapy, MTA-PTE Chronic Pain Research Group, Szentágothai Research Center, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary. Electronic address: eva.szoke@aok.pte.hu.
authors: É
authors: É
authors: Szőke
mesh_terms: D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D003412:Cricetulus; D006801:Humans; D019476:Insect Proteins / Q000494:pharmacology*; D051379:Mice; D010446:Peptide Fragments / Q000494:pharmacology*; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000494:pharmacology*; D017208:Rats, Wistar; D051239:Receptors, Vasoactive Intestinal Peptide, Type II / Q000037:antagonists & inhibitors / Q000378:metabolism; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I / Q000819:agonists / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000187:drug effects* / Q000502:physiology; D018689:Sensory System Agents / Q000494:pharmacology*; D050916:TRPV Cation Channels / Q000378:metabolism; D012668:Trigeminal Ganglion / Q000187:drug effects* / Q000502:physiology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*; D056969:Voltage-Sensitive Dye Imaging
chemical_list: D019476:Insect Proteins; D010446:Peptide Fragments; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D018689:Sensory System Agents; D050916:TRPV Cation Channels; C574015:maxadilan protein, Lutzomyia longipalpis; C075647:pituitary adenylate-cyclase-activating-peptide (6-38); C409214:vasoactive intestinal peptide (1-7)-GRF (8-27), Lys(15)-Arg(16)-Leu(27)-; C113198:vasoactive intestinal peptide (6-28); D014660:Vasoactive Intestinal Peptide; D002118:Calcium
keywords: G protein-coupled receptor; PAC1; PACAP6-38; VPAC1; VPAC2; trigeminal ganglia