title: Characterization of neurokinin-1 receptors in the submucosal plexus of guinea pig ileum.
abstract: This study combined immunohistochemical double-labeling techniques with functional studies to characterize the neurokinin-1 (NK1) receptors mediating neuronal and vasodilator responses in submucosal guinea pig ileum. NK1 receptor distribution in whole mount preparations of the submucosa was examined using a rabbit polyclonal antibody directed against the COOH terminus of the rat NK1 receptor. Results showed that 97% of neuropeptide Y immunoreactive submucosal neurons colocalized NK1 receptor immunoreactivity, whereas vasoactive intestinal polypeptide immunoreactive neurons were not NK1 immunoreactive. Intracellular recordings were made using neurobiotin-filled electrodes to enable reidentification of recorded neurons for immunohistochemical study. The selective NK1 agonists [Sar9,Met(O2)11]substance P (SP) and septide depolarized S-type submucosal neurons. Of these neurons, 36% were NK1 immunoreactive and 64% were not. NK1 immunoreactivity was not observed on submucosal arterioles, but superfusion of [Sar9,Met(O2)11]SP and septide dilated preconstricted submucosal arterioles. Agonist-evoked responses in both neurons and blood vessels were blocked by the selective NK1 antagonist CP-99994. These findings suggest that NK1 receptors are found on submucosal neurons and arterioles and that electrophysiological and immunohistochemical techniques may identify conformational variants of the receptor.
authors.affiliation: Gastrointestinal Disease Research Unit, Queen's University, Hotel Dieu Hospital, Kingston, Ontario, Canada.
authors.forename: B A
authors.initials: BA
authors.lastname: Moore
authors.forename: S
authors.initials: S
authors.lastname: Vanner
authors.forename: N W
authors.initials: NW
authors.lastname: Bunnett
authors.forename: K A
authors.initials: KA
authors.lastname: Sharkey
mesh_terms: D000818:Animals; D004558:Electric Stimulation; D005260:Female; D005725:Ganglia, Autonomic / Q000502:physiology; D006168:Guinea Pigs; D007082:Ileum / Q000098:blood supply / Q000294:innervation*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000098:blood supply / Q000294:innervation*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D018715:Microscopy, Video; D009130:Muscle, Smooth / Q000098:blood supply / Q000294:innervation; D009474:Neurons / Q000502:physiology*; D010446:Peptide Fragments / Q000494:pharmacology; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D011817:Rabbits; D051381:Rats; D018040:Receptors, Neurokinin-1 / Q000032:analysis* / Q000502:physiology; D013368:Submucous Plexus / Q000187:drug effects / Q000502:physiology*; D013373:Substance P / Q000031:analogs & derivatives / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
chemical_list: D010446:Peptide Fragments; D018040:Receptors, Neurokinin-1; C062618:substance P, Sar(9)-Met(O2)(11)-; D013373:Substance P; C054725:septide; D011761:Pyrrolidonecarboxylic Acid