title: Intracerebroventricular administration of apelin-13 inhibits distal colonic transit in mice.
abstract: Apelin is a novel bioactive peptide as the endogenous ligand for the orphan G-protein-coupled receptor (GPCR), APJ, a receptor distributed in various tissues such as the hypothalamus and the gastrointestinal tract. Recent reports showed that apelin regulated many biological functions, including blood pressure, neuroendocrine, drinking behavior and food intake. However, the role of apelin in regulating gastrointestinal motility remains unknown. The present study aimed to investigate the actions of intracerebroventricularly administered apelin-13 on colonic transit as well as the actions of apelin-13 on the contraction of isolated distal colon in vitro. Intracerebroventricular (i.c.v.) injection of apelin-13 (0.3, 0.5, 1 and 3 μg/mouse) dose-dependently inhibited fecal pellet output and bead expulsion. This effect was significantly antagonized by the APJ receptor antagonist apelin-13(F13A), indicating an APJ receptor-mediated mechanism. Furthermore, naloxone could also reverse the inhibitory effect of apelin-13 on fecal pellet output and bead expulsion, suggesting the involvement of opioid receptors in the suppressive effect of apelin-13 on distal colon transit. However, apelin-13 (10⁻⁸-10⁻⁶ M) did not affect distal colonic contractions in vitro.
authors.affiliation: Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, PR China.
authors.forename: Yan-Jie
authors.initials: YJ
authors.lastname: Yang
authors.forename: Shuang-Yu
authors.initials: SY
authors.lastname: Lv
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Xiu
authors.forename: Ning
authors.initials: N
authors.lastname: Xu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Chen
mesh_terms: D000818:Animals; D000075244:Apelin Receptors; D003106:Colon / Q000187:drug effects*; D005243:Feces; D005772:Gastrointestinal Transit / Q000187:drug effects*; D007276:Injections, Intraventricular; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D008297:Male; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors
chemical_list: D000075244:Apelin Receptors; C491285:Aplnr protein, mouse; D036341:Intercellular Signaling Peptides and Proteins; D043562:Receptors, G-Protein-Coupled; C495199:apelin-13 peptide