Presence, distribution, and pharmacological effects of neuropeptide Y in mammalian gastrointestinal tract

Abstract

The quantitative distribution of neuropeptide Y (NPY) immunoreactivity has been determined along the length of the gastrointestinal tract in three mammalian species; rat, pig, and guinea pig. The peptide was shown to be present in all regions studied and in all three species. Exceptionally high concentrations were found in the region of the lower esophageal sphincter. Pretreatment of rats with 6-hydroxydopamine depleted NPY concentrations by 30-40%, indicating that NPY is colocalized in part with adrenergic nerves. Characterization of the NPY immunoreactivity by high-pressure liquid chromatography revealed a single major peak. NPY immunoreactivity derived from rat extracts eluted consistently earlier from the column than synthetic porcine standard, indicating minor species differences. Pharmacological studies using longitudinal muscle from guinea pig terminal ileum demonstrated that NPY caused a dose-dependent inhibition of the electrically stimulated, neurally mediated contraction of longitudinal smooth muscle. This suggested that NPY may act presynaptically to inhibit cholinergic transmission. The effects of various NPY fragments were also tested on the same preparation. The C-terminal fragments were active but were considerably less potent than NPY, while the free acid form of NPY and N-terminal fragment (1-19) were completely inactive. Thus, this study has demonstrated the presence of NPY in the gastrointestinal tract of various species, particularly within the lower esophageal sphincter. The pharmacological actions of the peptide suggest a role in the control of nonvascular smooth muscle tone.

Effect on Components of the Intestinal Microflora and Plasma Neuropeptide Levels of Feeding Lactobacillus delbrueckii , Bifidobacterium lactis , and Inulin to Adult and Elderly Rats

“…It has been previously shown that the frequency of NPY-containing cells increases with age in the rat colon (47) and that the number of NPY-containing cells is also significantly increased in constipated patients (45). A higher level of portal plasma NPY may suggest alterations in GI motility and transit time of digesta, since NPY has been shown to alter the contraction of the gastrointestinal smooth muscles (1,48) and the GI motility pattern (12). A high NPY level can also affect digestion due to the possible inhibition of pancreatic enzyme secretion (21).…”

Localization and characterization of neuropeptide Y binding sites in porcine and human colon

“…Specific binding of ['25I]-BH-NPY to colonic vessels may be present, but at a low density by comparison with non-specific binding. Modin et al (1991) (Allen et al, 1987).…”

Changes in vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide and neuropeptide Y-ergic structures of the enteric nervous system in the carcinoma of the human large intestine.

“…It has also been shown that PACAP is a neurotransmitter suppressing the contraction of the intestinal muscle, and in the region of the mucous membrane it cause increases of intestinal secretion [7]. It is also known that NPY inhibits contraction of the intestinal muscle, probably by suppressing the cholinergic transmission and also in the intestinal wall there are postganglionic nerve fibres containing NPY which innervate the submucosal arterioles, producing their constriction [8][9][10]. Investigations of the enteric nervous system in inflammatory diseases of the large intestine have shown morphological changes in this system.…”