Neuropeptide distributions in the colon, cecum, and jejunum of the horse.
Abstract: The pelvic flexure portion of the equine large colon is the proposed location of a pacemaker mechanism. This study was conducted to ascertain whether the distribution of certain putative neurotransmitters differs at the pelvic flexure compared to other sampling sites. Tissue samples were collected from the intestinal tracts of six horses. Serial sections from these samples were reacted with primary antisera specific for substance P, vasoactive intestinal polypeptide (VIP), methionine-Enkephalin, and calcitonin gene-related peptide (CGRP). The regional distribution of immunoreactive neuronal elements was uniform for each of the neuropeptides except VIP. Although neurons exhibiting VIP-like immunoreactivity were abundant throughout the colon, they were somewhat more plentiful near the apex of the pelvic flexure and the left dorsal colon. These neurons may participate in the initiation and propagation of the propulsive/retropulsive contraction waves, which emanate from this location and are believed to lend a sphincter-like capacity to the pelvic flexure. The submucosal plexus was replete with neurons with intense substance P and VIP-like reactivity. Reactive fibers left submucosal ganglia to project to the intestinal mucosa, reflecting a possible secretogogic role for these neurons. This role may be especially important for the horse as a hindgut fermenter. There were abundant methionine-Enkephalin and substance P-like reactive varicosities throughout the myenteric plexus, many of which established a pericellular plexus of varicose fibers. The abundance of these varicosities, which may correlate with a high degree of neuronal integration, did not vary regionally. These data may enhance our understanding of both normal colonic peristalsis and motility disorders caused by a depletion of these neuropeptides.
Publication Date: 1993-06-01 PubMed ID: 7687832DOI: 10.1002/ar.1092360207Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This study investigates the distribution of certain neurotransmitters in the large colon of horses, to find out if there are differences in neurotransmitter presence in various parts of the intestines. This could provide valuable understanding about normal intestinal movement in horses and disorders caused by a depletion of these neurotransmitters.
Research Methodology
- The research team collected tissue samples from different sections of the intestinal tracts of six horses.
- These samples underwent a reaction with antisera specific for certain neurotransmitters: substance P, vasoactive intestinal polypeptide (VIP), methionine-Enkephalin, and calcitonin gene-related peptide (CGRP).
Findings
- The distribution of reactive neuronal elements, indicative of the presence of the neurotransmitters, was uniform across the sections for all neurotransmitters except VIP.
- Neurons showing VIP-like immunoreactivity were significantly more prevalent near the apex of the pelvic flexure and the left dorsal colon.
- The submucosal plexus, a layer of the intestinal wall, had abundant neurons with high reactivity for substance P and VIP. These could have a vital role in secretion processes in the intestines.
- Lots of reactive varicosities, or swollen areas in the neuronal structures, apparently showing methionine-Enkephalin and substance P-like reactivity were found in the channels running through the intestinal muscles (myenteric plexus), which could be associated with a high degree of neuronal integration. However, the quantity of these varicosities did not vary with the region.
Implications
- The higher prevalence of VIP-like immunoreactivity neurons in certain areas of the colon suggests that these neurons might be implicated in the contraction waves necessary for propelling material through the intestines.
- Submucosal neurons with substance P and VIP-like reactivity could help in secretion processes, which is especially important for horses due to their eating habits.
- The presence of methionine-Enkephalin and substance P-like reactive varicosities throughout the myenteric plexus, indicates possible widespread neuronal integration.
- These findings contribute to the understanding of regular intestinal movements in horses and could help detect potential causes for motility disorders resulting from the reduction of these neurotransmitters.
Cite This Article
APA
Burns GA, Cummings JF.
(1993).
Neuropeptide distributions in the colon, cecum, and jejunum of the horse.
Anat Rec, 236(2), 341-350.
https://doi.org/10.1002/ar.1092360207 Publication
Researcher Affiliations
- Department of Veterinary and Comparative Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, Washington State University, Pullman 99164-6520.
MeSH Terms
- Animals
- Calcitonin Gene-Related Peptide / analysis
- Cecum / chemistry
- Cecum / cytology
- Colon / chemistry
- Colon / cytology
- Enkephalin, Methionine / analysis
- Female
- Horses
- Jejunum / chemistry
- Jejunum / cytology
- Male
- Myenteric Plexus / chemistry
- Neurons / chemistry
- Neuropeptides / analysis
- Substance P / analysis
- Vasoactive Intestinal Peptide / analysis
Citations
This article has been cited 3 times.- Moore RM, Sedrish SA, Holmes EP, Koch CE, Venugopal CS. Role of endothelium and nitric oxide in modulating in vitro responses of colonic arterial and venous rings to vasodilatory neuropeptides in horses. Can J Vet Res 2005 Apr;69(2):116-22.
- Hudson NP, Pearson GT, Mayhew IG. Tissue culture of the enteric nervous system from equine ileum. Vet Res Commun 2000 Jul;24(5):299-307.
- Pearson GT. Structural organization and neuropeptide distributions in the equine enteric nervous system: an immunohistochemical study using whole-mount preparations from the small intestine. Cell Tissue Res 1994 Jun;276(3):523-34.
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