Intramural distribution of regulatory peptides in the sigmoid-recto-anal region of the human gut.

Abstract

SUMMARY The distribution of regulatory peptides was studied in the separated mucosa, submucosa and muscularis externa taken at 10 sampling sites encompassing the whole human sigmoid colon (five sites), rectum (two sites), and anal canal (three sites). Consistently high concentrations of VIP were measured in the muscle layer at most sites (proximal sigmoid: 286 (16) (SE). Conversely, substance P concentrations showed an obvious decline in the recto-anal muscle (mid sigmoid: 19 (2 0) pmol/g, distal rectum: 7 1 (1 3), upper anal canal: 1-6 (0 6)). Somatostatin was mainly present in the sigmoid mucosa and submucosa (37 (9 3) and 15 (3-5) pmol/g, respectively) and showed low, but consistent concentrations in the muscle (mid sigmoid: 2-2 (0 7) pmol/g, upper anal canal: 1 5 (0 8)). Starting in the distal sigmoid colon, a distinct peak of tissue NPY was revealed, which was most striking in the muscle (of mid sigmoid: 16 (3-9) pmol/g, upper rectum: 47 (7-8), anal sphincter: 58 (14)). Peptide YY was confined to the mucosa and showed an earlier peak (upper sigmoid: 709 (186) pmol/g, mid-distal sigmoid: 1965 (484)). A clear differential distribution of regulatory peptides was thus shown in the region studied. A possible role is suggested for NPY and VIP containing nerves in the effector control of the human internal anal sphincter.The whole region of the human gut composed of the sigmoid colon, rectum and anal canal can probably be considered as a complex regulatory area, devoted to the final processing and expulsion of bowel contents, culminating in defecation.' In fact, although distinct sphincteric structures are conspicuously absent at this level, the rectosigmoid junction itself has been proposed to act as a regulatory zone.' Below the rectum, a well defined smooth sphincter-that is, the internal anal sphincter, is found at the termination of the alimentary canal. ' Within this complex region, intrinsic nerves appear to play a crucial role. This is clearly the case for the inhibitory control of the internal anal sphincter, exerted by the rectoanal reflex and largely mediated

Vasoactive intestinal polypeptide and nitric oxide synthase distribution in the enteric plexuses of the human colon: an histochemical study and quantitative analysis

“…In fact, in Bouin's fixed and paraffin-embedded specimens, VIP-positive neurons and fibers have been found lacking in the myenteric plexus and circular muscle layer of the cecocolonic junction, while nitric oxide synthase (NOS) positive ones were numerous. The presence in the human colon of VIP-positive (Larsson et al 1976;Ferri et al 1983Ferri et al , 1988Sundler et al 1992) and either NOS-or NADPH-diaphorase positive (Hanani et al 1993;Timmermans et al 1994;Krammer et al 1994) nerves and neurons has already been reported, but without any indication as to possible differences in their distribution according to colonic region.…”

Age-related changes in substance P-immunoreactive nerve structures of the rat recto-anal region

“…Among the enteric neuropeptides, substance P (SP) has received considerable attention because of its role as a pivotal sensory mediator of intestinal motility in animal species, including humans [8][9][10]. This peptide was first isolated from extracts of the brain and gut.…”

Concentration of vasoactive intestinal polypeptide, neuropeptide Y and calcitonin gene related peptide in neoplastic tissue of the human large intestine

“…In the human large intestine the presence of NPY was found mostly in the muscular layer, and also a large amount of NPY was found within the sphincters of the gastrointestinal tract of man, which may suggest a role of this neuropeptide in the regulation of the tonus of the musculature of these anatomical structures. It was also found that NPY inhibits the contraction of the intestinal muscular layer [2,17,19,27,28]. The present study showed lower concentration of NPY in tissues of the large intestine infiltrated by cancer than in healthy intestinal tissues.…”

“…In physiological conditions, within nervous structures supplying human large intestines the presence of vasoactive intestinal polypeptide (VIP), calcitonin gene related peptide (CGRP) and neuropeptide Y (NPY) was found [1][2][3][4][5].…”