title: Distribution of apelin, the endogenous ligand of the APJ receptor, in the lizard Podarcis sicula.
abstract: Apelin is a novel bioactive peptide that has been isolated from bovine stomach extracts and identified as the endogenous ligand for the APJ receptor. Although the main physiological functions of apelin have not yet been clarified, it is known that apelin is involved in the regulation of blood pressure, central control of body fluid homeostasis and the modulation of immune response. In order to investigate the distribution of apelin in reptiles, we have performed an immunohistochemical analysis on tissues of the lizard Podarcis sicula. The peptide was found to be widely distributed, although its cellular localization differed in the various organs examined. A strong immunopositivity was found in the heart, stomach and intestine. In the spleen, an intense apelin immunopositivity was restricted to a discrete number of cells scattered throughout the red pulp and co-localized with immunoglobulin kappa and lambda chains, suggesting an analogous function of this peptide in immune responses also in reptiles. Intriguingly, apelin immunoreactivity was discretely localized in endothelial cells in the lung and thyroid gland. In the light of these data, we conclude that apelin may have multiple functions in reptiles.
authors.affiliation: Department of Evolution and Comparative Biology, Federico II University, Naples, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: De Falco
authors.forename: Valentina
authors.initials: V
authors.lastname: Fedele
authors.forename: Tiziana
authors.initials: T
authors.lastname: Russo
authors.forename: Francesca
authors.initials: F
authors.lastname: Virgilio
authors.forename: Rosaria
authors.initials: R
authors.lastname: Sciarrillo
authors.forename: Stanislao
authors.initials: S
authors.lastname: Leone
authors.forename: Vincenza
authors.initials: V
authors.lastname: Laforgia
authors.forename: Antonio
authors.initials: A
authors.lastname: De Luca
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D008116:Lizards / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D043562:Receptors, G-Protein-Coupled