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Calcitonin gene-related peptide neurons innervating the canine digestive system
No full textThe pattern of nerve cells and fibers containing calcitonin gene-related peptide immunoreactivity (CGRP-IR) was investigated in the canine digestive tract by means of immunohistochemistry. CGRP-IR nerve fibers innervate all the layers of the gut, including the vasculature, with different densities depending on the region. CGRP-IR processes are sparse in the esophagus and stomach, where they are mostly confined to the enteric plexuses and vasculature. CGRP-IR fibers are quite abundant in the small and large intestine, where they form dense arborizations in the mucosa, and are numerous in the muscularis mucosae, deep muscular plexus and circular muscle. The myenteric and submucous plexuses of the intestine contain dense networks of CGRP-IR fibers and numerous CGRP-IR ganglion cells. On the other hand, in the enteric ganglia of the esophagus and stomach, in the intrapancreatic ganglia and in the ganglionated plexus of the gallbladder, CGRP-IR is restricted to non-varicose processes. A moderate density of CGRP-IR fibers supplies the endocrine and exocrine pancreas, and the fibromuscular layer and lamina propria of the gallbladder. The density of CGRP innervation in different regions can be summarized as follows: intestine≫pancreas and gallbladder≥antrum>cardia>gastric corpus and distal esophagus. CGRP- and tachykinin (TK)-IRs are colocalized in a substantial population of fibers, particularly those distributed to the mucosa, muscularis mucosae and vasculature, whereas there was no evidence of colocalization in intrinsic ganglion cells. The present results suggest that (1) the CGRP innervation of the dog digestive system includes an intrinsic and an extrinsic component, and (2) CGRP-and TK-IRs are co-expressed in extrinsic nerve fibers. These findings extend previous observations in rats and guinea pigs and provide insights into the sites of action of CGRP in the digestive system of the dog, which has served as a model for CGRP functional studies
ALPHA‐TRANSDUCIN EXPRESSION IN THE GASTROINTESTINAL TRACT OF THE EUROPEAN SEA BASS (DICENTRARCHUS LABRAX)
No full textThe gustatory system plays the critical function of distinguishing between nutrients and non‐nutrient,
potentially dangerous substances (1) allowing adaptation to different habitats (2). Different tastes are
detected by G protein couple receptors and their signalling molecules,including the heterotrimeric G
proteins,α‐transducin (Gαtran)and α‐gustducin(Gαgust) (3,4). Taste‐related molecules have been
discovered in the gastrointestinal tract of a variety of species from fish to humans. In this study we
examined the distribution and peptide content of cells expressing Gαtran‐immunoreactivity in the
gastrointestinal(GI)mucosa of the sea bass.
Adult European sea bass(Dicentrarchus labrax)were sampled from different tanks and euthanized by an
overdose of anaesthetic. The stomach,pyloric caeca and intestine were harvested;the intestine was divided
into three regions: cranial, middle and caudal. Tissue sections were processed for immunofluorescence
with the following primary antisera: Gαtran, Gαgust, ghrelin(GHR), 5‐hydroxytryptamine (5‐HT), obestatin
(OB), somatostatin (SOM), gastrin/cholecystokinin (GAS/CCK), glucagon‐like peptide‐1 (GLP‐1), calcitonin
gene‐related peptide (CGRP) and substance P(SP). Each antibody was either used alone for single labelling
or in combination with others for double labelling.
Gαtran immunoreactivity was observed throughout the sea bass GI tract, but was more abundant in the
stomach compared to the intestine with decreasing density of cells from the cranial to the caudal regions.
Specificity of Gαtran and Gαgust immunostaining was established by Western blot analysis, which showed
immunopositive bands at the expected molecular weight of ~45 and ~40 kDa, respectively, in sea bass gut
tissue as well as in positive tissue (e.g. brain and eye). Staining specificity was also demonstrated by
immunoblocking with the homologous peptides. Colocalization of Gαtran and Gαgust immunoreactivity
was visualized in some cells in the stomach. A subpopulation of Gαtran immunoreacitve cells in the
stomach also contained GHR, OB or 5‐HT immunoreactivity. Colocalization of Gαtran immumoreactivity
with SOM, GAS/CCK, GLP‐1, SP, or CGRP immunistaining was not observed in any GI tract regions.
Our data provide evidence that Gαtran and Gαgust are involved in chemosensory transmission in the sea
bass GI enteroendocrine system. It is likely that nutrients activate taste receptors and their signalling
molecules to induce the release of peptides from enteroendocrine cells, which in turn activate other cells
types directly or via neural reflexes thus initiating a variety of physiological responses controlling GI
functions and caloric intake.
1 Sternini C. Am J Physiol Gastrointest Liver Physiol, 2007, 292:G457‐G461.
2 Barreiro‐Iglesias et. all, Brain Behav Evol 2010,75:241‐250.
3 Mazzoni et. all, J Cell Mol Med 2013, Apr;17(4):466‐74.
4 Oike H et. all, J Neurosci, 2007, 27:5584‐5592
Neurokinin 1 receptor expression in the rat retina
No full textTachykinin (TK) peptides influence neuronal activity in the inner retina of mammals. The
aim of this investigation was to determine the cellular localization of the neurokinin 1
receptor (NK1), whose preferred ligand is the TK peptide substance P (SP), in the rat retina.
These studies used a polyclonal antiserum directed to the C-terminus of rat NK1. The
majority of NK1-immunoreactive (IR) cells were located in the proximal inner nuclear layer
(INL), and very rarely they were found in the distal INL. Some small and large NK1-IR
somata were present in the ganglion cell layer. NK1-IR processes were densely distributed
across the inner plexiform layer (IPL) with a maximum density over lamina 2 of the IPL.
Immunoreactive processes also crossed the INL and ramified in the outer plexiform layer
where they formed a sparse meshwork. NK1-IR processes were rarely observed in the optic
nerve fiber layer. Double-label immunofluorescence studies with different histochemical
markers for bipolar cells indicated that NK1 immunoreactivity was not present in bipolar
cells. Together, these observations indicate that NK1 immunoreactivity is predominantly
expressed by amacrine, displaced amacrine, interplexiform, and some ganglion cells. Doublelabel
immunofluorescence experiments were also performed to characterize NK1-containing
amacrine cells. Sixty-one percent of the g-aminobutyric acid (GABA)-IR cells, 71% of the large
tyrosine hydroxylase (TH)-IR cells, and 100% of the small TH-IR cells contained NK1
immunoreactivity. In addition, most (91%) of the NK1-IR cells had GABA immunoreactivity.
In contrast, vasoactive intestinal polypeptide-, TK-, choline acetyltransferase-, and parvalbumin-
IR amacrine cells did not express NK1 immunoreactivity. Overall, the present findings
suggest that SP acts directly upon several cell populations, including GABA-containing
amacrine cells and ganglion cells, to influence visual information processing in the inner
retina
Etorphine increases the number of μ-opioid receptor-positive cells in the cerebral cortex
No full textNeurotrophin-3 and neurotrophin receptor immunoreactivity in peptidergic enteric neurons
No full textIn the rat small intestine, neurotrophin-3 immunoreactivity was identified in ganglion cells and in processes mostly innervating the mucosa and occasionally the muscle layer and vasculature. The vast majority of neurotrophin-3 immunoreactive neurons contained vasoactive intestinal polypeptide (VIP), but not substance P or related tachykinin (SP/TK). Neurotrophin receptors visualized by pan-trk immunoreactivity were found in numerous ganglion cells of both plexuses and in nerve processes in the intestinal wall. Pan-trk submucosal neurons contained VIP (36%) or SP/TK-IR (47%). Pan-trk myenteric neurons contained VIP-IR (57%) or SP/TK (27%). Our data suggest that neurotrophin-3 and neurotrophin receptors may be involved in the maintenance of enteric neuronal circuits, transmission and phenotypic expression. Copyright (C) 2000 Elsevier Science Inc
Fos protein expression in the nucleus of the solitary tract in response to intestinal nutrients in awake rats
No full textNutrients in the intestine inhibit food intake via an action on the vagal afferent pathway. The aim of the present study was to use immunochemical detection of Fos protein-like immunoreactivity (FLI) in the brainstem to trace the neuronal pathways activated by intestinal nutrients. Perfusion of the intestine of awake rats via an indwelling duodenal catheter with iso-osmotic mannitol, hydrochloric acid or casein hydrolysate had no effect on the number of FLI neurons in the nucleus of the solitary tract (NTS). Lipid emulsion (20%) and 2.7 M glucose significantly increased the number of immunopositive cells in the NTS. There was a significant increase in the number of immunopositive cells from caudal to rostral NTS. Nutrients effective at decreasing food intake (carbohydrate and fat) produced significant increases in Fos-like immunopositive cells in the NTS
Expression of galanin receptor messenger RNAs in different regions of the rat gastrointestinal tract
No full textCalcitonin gene-related peptide (CGRP) in the cat neocortex: Evidence for a sparse but widespread network of immunoreactive fibers.
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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