Distribution of galanin receptor 1 immunoreactivity in the rat stomach and small intestine.
Galanin affects gastrointestinal functions by activating different G protein-coupled receptors. Here, we identified the sites of expression of the galanin receptor 1 (GAL-R1) subtype in the rat stomach and small intestine by using immunohistochemistry with an antibody raised to the third intracellular loop of rat GAL-R1 (GAL-R1(Y225-238)) and confocal microscopy. Antibody specificity was confirmed by (1) the detection of a band at approximately 70 kDa in Western blot of membranes from GAL-R1 transfected cells, (2) the cell surface staining of GAL-R1 transfected cells, which was not detected in control cells, and (3) the abolition of Western signal and tissue immunostaining by preadsorbing the antibody with the peptide used for immunization. GAL-R1 immunoreactivity was localized to the cell surface of enterochromaffin-like cells, and of myenteric and submucous neurons, and to fibers distributed to the plexuses, interconnecting strands, muscle layers, vasculature, and mucosa. A dense network of GAL-R1 immunoreactivity was observed in the deep muscular plexus in very close association with interstitial cells of Cajal visualized by c-kit immunostaining. In the ileum, 81.6% of GAL-R1 myenteric neurons and 70.7% of GAL-R1 submucosal neurons were substance P immunoreactive. Vasoactive intestinal polypeptide immunoreactivity was found in 48.3% of GAL-R1 submucosal neurons, but not in GAL-R1 myenteric neurons. These findings support the hypothesis that GAL-R1 mediates galanin actions on gastrointestinal motility and secretion by modulating the release of other neurotransmitters and contributes to galanin-induced inhibition of gastric acid secretion by means of the suppression of endogenous histamine release.
Pham
Thomas
T
CURE Digestive Diseases Research Center, Division of Digestive Diseases, University of California, Los Angeles, California 90095, USA.
Guerrini
Stefania
S
Wong
Helen
H
Reeve
Joseph
J
Sternini
Catia
C
D000818:Animals; D000918:Antibody Specificity / Q000276:immunology; D002478:Cells, Cultured; D017615:Enteric Nervous System / Q000166:cytology / Q000378:metabolism*; D004759:Enterochromaffin Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D019004:Galanin / Q000378:metabolism*; D005753:Gastric Mucosa / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007421:Intestine, Small / Q000166:cytology / Q000294:innervation / Q000378:metabolism*; D008297:Male; D009046:Motor Neurons / Q000166:cytology / Q000378:metabolism; D009092:Mucous Membrane / Q000166:cytology / Q000294:innervation / Q000378:metabolism; D009130:Muscle, Smooth / Q000166:cytology / Q000294:innervation / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D044088:Receptors, Galanin; D018013:Receptors, Neuropeptide / Q000276:immunology / Q000378:metabolism*; D013270:Stomach / Q000166:cytology / Q000294:innervation; D013373:Substance P / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism
D044088:Receptors, Galanin; D018013:Receptors, Neuropeptide; D013373:Substance P; D014660:Vasoactive Intestinal Peptide; D019004:Galanin