title: Localisation and activation of the neurokinin 1 receptor in the enteric nervous system of the mouse distal colon.
abstract: The substance P neurokinin 1 receptor (NK1R) regulates motility, secretion, inflammation and pain in the intestine. The distribution of the NK1R is a key determinant of the functional effects of substance P in the gut. Information regarding the distribution of NK1R in subtypes of mouse enteric neurons is lacking and is the focus of the present study. NK1R immunoreactivity (NK1R-IR) is examined in whole-mount preparations of the mouse distal colon by indirect immunofluorescence and confocal microscopy. The distribution of NK1R-IR within key functional neuronal subclasses was determined by using established neurochemical markers. NK1R-IR was expressed by a subpopulation of myenteric and submucosal neurons; it was mainly detected in large multipolar myenteric neurons and was colocalized with calcitonin gene-related peptide, neurofilament M, choline acetyltransferase and calretinin. The remaining NK1R-immunoreactive neurons were positive for nitric oxide synthase. NK1R was expressed by most of the submucosal neurons and was exclusively co-expressed with vasoactive intestinal peptide, with no overlap with choline acetyltransferase. Treatment with substance P resulted in the concentration-dependent internalisation of NK1R from the cell surface into endosome-like structures. Myenteric NK1R was mainly expressed by intrinsic primary afferent neurons, with minor expression by descending interneurons and inhibitory motor neurons. Submucosal NK1R was restricted to non-cholinergic secretomotor neurons. These findings highlight key differences in the neuronal distribution of NK1R-IR between the mouse, rat and guinea-pig, with important implications for the functional role of NK1R in regulating intestinal motility and secretion.
authors.affiliation: Department of Pediatric Surgery, The University of Chicago, Chicago, IL, 60637, USA.
authors.forename: Juan-Carlos
authors.initials: JC
authors.lastname: Pelayo
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Veldhuis
authors.forename: Emily M
authors.initials: EM
authors.lastname: Eriksson
authors.forename: Nigel W
authors.initials: NW
authors.lastname: Bunnett
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Poole
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D064032:Calbindin 2 / Q000378:metabolism; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002795:Choline O-Acetyltransferase / Q000096:biosynthesis; D003106:Colon / Q000294:innervation* / Q000378:metabolism; D017615:Enteric Nervous System / Q000378:metabolism*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D041981:Gastrointestinal Tract / Q000294:innervation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016900:Neurofilament Proteins / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D018040:Receptors, Neurokinin-1 / Q000096:biosynthesis / Q000276:immunology / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000096:biosynthesis
chemical_list: D000906:Antibodies; D064032:Calbindin 2; D016900:Neurofilament Proteins; D018040:Receptors, Neurokinin-1; C061195:neurofilament protein M; D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D019001:Nitric Oxide Synthase; D002795:Choline O-Acetyltransferase; D015740:Calcitonin Gene-Related Peptide