Characterization of Vasoactive Intestinal Peptide/Pituitary Adenylate Cyclase-Activating Polypeptide Receptors in Chick Cerebral Cortex

Abstract

In this study receptors for vasoactive intestinal peptide (VIP) and pituitary adenylate cyclase-activating polypeptide (PACAP) were characterized in chick cerebral cortex by an in vitro binding technique, using 125I-labeled VIP ([125I]-VIP) as a ligand. The specific binding of [125I]-VIP to chick cerebral cortical membranes was found to be rapid, stable, saturable, reversible, and of high affinity. Saturation analysis resulted in a linear Scatchard plot, suggesting binding to a single class of receptor binding sites with high affinity (Kd = 0.21 nM) and low capacity (Bmax = 19.5 fmol/mg protein). The relative rank order of potency of the tested peptides to inhibit [125I]-VIP binding to chick cerebrum was VIP (chicken) > or = VIP (mammalian) > or = PACAP27 > or = PACAP38 >> VIP6-28 (mammalian) > PHI (porcine) >> neurotensin6-11-chicken VIP7-28 > neurotensin6-11-mammalian VIP7-28 >>> VIP16-28 (chicken; inactive) approximately secretin (inactive). About 60% of [125I]-VIP-binding sites in chick cerebral cortex were sensitive to Gpp(NH)p, a nonhydrolyzable analog of GTP. It has been concluded that the cerebral cortex of chick, in addition to PAC1 receptors, contains a population of VPAC-type receptors.

Duck Pancreatic Acinar Cell as a Unique Model for Independent Cholinergic Stimulation–Secretion Coupling

“…The Ser 2 to Ile 2 substitution in birds does not seem to affect the PACAP efficacy; similar concentration ranges are used in ducks and geese (Nowak et al 2000), and mammalian PACAP-27 and -38 have been used for works done in birds (Zawilska et al 2004). Although significant sequence differences have been noted between bird and mammalian VIP, avian VIP has been found to be more potent than mammalian VIP (Zawilska et al , 2004. The lack of effect of VIP/PACAP found in the present work in duck pancreatic acini could not be explained by the differences in VIP/PACAP amino acid sequence.…”

“…The amino acid sequence of PACAP has been known to be highly conserved during evolution (Mirabella et al 2001(Mirabella et al , 2002Arimura 2007), with the PACAP sequence being identical in mammals, but shows one amino acid difference in birds (chick, turkey; Vaudry et al 2000;Nowak and Zawilska 2003). The Ser 2 to Ile 2 substitution in birds does not seem to affect the PACAP efficacy; similar concentration ranges are used in ducks and geese (Nowak et al 2000), and mammalian PACAP-27 and -38 have been used for works done in birds (Zawilska et al 2004). Although significant sequence differences have been noted between bird and mammalian VIP, avian VIP has been found to be more potent than mammalian VIP (Zawilska et al , 2004.…”

Presence of PACAP and VIP in Embryonic Chicken Brain

“…The presence and distribution of PACAP and its receptors and the gene encoding PACAP in the chicken are well known 3 . Several studies have been carried out on receptor binding and the effects of PACAP on signal transduction pathways in the chicken have also been shown 3–5 . However, less is known about the expression and functions of PACAP in the embryonic chicken brain.…”

“…3 Several studies have been carried out on receptor binding and the effects of PACAP on signal transduction pathways in the chicken have also been shown. [3][4][5] However, less is known about the expression and functions of PACAP in the embryonic chicken brain. In vitro, the presence of PACAP has been shown in 3.5-embryonic day (ED)-old chick neuroblasts 6 and PACAP can be detected in nerves of the chicken gut as early as ED 4-5.…”

Secretin receptor involvement in prion‐infected cells and animals

“…SctR belongs to the type II G‐protein‐coupled receptor family that also includes VIP, PACAP, glucagon, and glucagon‐like peptide receptors [34]. Sct is able to bind to these related receptors, which have similar signaling effects in cells [35–39], and conversely the corresponding peptide hormones in this family can bind SctR [40–42].…”