title: Actions of PACAP and VIP on melanotrope cells of Xenopus laevis.
abstract: The neuropeptides, pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) are implicated in the regulation of gene expression and hormone secretion in mammalian melanotrope cells and a mammalian pro-opiomelanocortin (POMC)-producing tumor cell line, but the physiological relevance of this regulation is elusive. The purpose of the present study was to establish if these peptides affect biosynthetic and secretory processes in a well-established physiological model for endocrine cell functioning, the pituitary melanotrope cells of the amphibian Xenopus laevis, which hormonally control the process of skin color adaptation to background illumination. We show that both PACAP and VIP are capable of stimulating the secretory process of the Xenopus melanotrope cell. As the peptides are equipotent, they may exert their actions via a VPAC receptor. Moreover, PACAP stimulated POMC biosynthesis and POMC gene expression. Strong anti-PACAP immunoreactivity was found in the pituitary pars nervosa (PN), suggesting that this neurohemal organ is a source of neurohormonal PACAP action on the melanotropes in the intermediate pituitary. We propose that the PACAP/VIP family of peptides has a physiological function in regulating Xenopus melanotrope cell activity during the process of skin color adaptation.
authors.affiliation: Department of Cellular Animal Physiology, Faculty of Science, Integrative Physiology, EURON, Radboud University Nijmegen, 6525 ED Nijmegen, The Netherlands.
authors.forename: Adhanet H
authors.initials: AH
authors.lastname: Kidane
authors.forename: Peter M J M
authors.initials: PM
authors.lastname: Cruijsen
authors.forename: Maria A
authors.initials: MA
authors.lastname: Ortiz-Bazan
authors.forename: Hubert
authors.initials: H
authors.lastname: Vaudry
authors.forename: Jerome
authors.initials: J
authors.lastname: Leprince
authors.forename: Frouwke J
authors.initials: FJ
authors.lastname: Kuijpers-Kwant
authors.forename: Eric W
authors.initials: EW
authors.lastname: Roubos
authors.forename: Bruce G
authors.initials: BG
authors.lastname: Jenks
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D007150:Immunohistochemistry; D052717:Melanotrophs / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000494:pharmacology*; D010902:Pituitary Gland / Q000378:metabolism; D011333:Pro-Opiomelanocortin / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*; D014982:Xenopus laevis
chemical_list: D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D014660:Vasoactive Intestinal Peptide; D011333:Pro-Opiomelanocortin