Immunohistochemical analysis of substance P-containing neurons in rat small intestine

Abstract

The neuropeptide substance P (SP) is involved in the regulation of epithelial secretion and motility in the rat small intestine. The morphology, chemical profiles and proportion of SP-containing enteric neurons in this tissue have been examined by immunohistochemical analysis of whole-mount preparations obtained from colchicine-treated rats. In the submucosal plexus of the duodenum, jejunum and ileum, the proportion of SP-positive neurons is 53%, 51% and 49%, respectively. All SP-positive submucosal neurons are positive for neurofilament 200 (NF-200) and calretinin. Immunoreactivity for calcitonin gene-related peptide (CGRP) is detectable in 55% of the SP-positive submucosal neurons. Some SP-positive submucosal neurons have two or more long processes emerging from an oval or round cell body, a characteristic of the Dogiel type II neuron (type II neuron; a putative intrinsic primary afferent neuron). About one-third of the neurons in the myenteric plexus are positive for SP and a majority of them are NF-200/calretinin-positive type II neurons. Immunoreactivity for the SP receptor neurokinin-1 receptor (NK1R) has been detected mainly in the submucosal and myenteric NF-200-positive neurons, which are expected to contain SP. These neurons possibly stimulate each other via SP release. Most of the submucosal and myenteric neurons, including type II neurons, show immunoreactive for the prostaglandin E2 receptor EP3 receptor (EP3R). Thus, SP/NF-200/calretinin/NK1R/EP3R is the common chemical profile of type II neurons in the rat small intestine. The proportion of SP-immunopositive submucosal neurons (49%-53%) is higher in the rat small intestine than in the colon (≤11%) and around 50% are positive for CGRP.

Substance P as a neuronal factor in the enteric nervous system of the porcine descending colon in physiological conditions and during selected pathogenic processes

“…The obtained results show that SP-positive neuronal structures are present in all parts of the wall of the porcine descending colon with the exception of the outer muscular layer. SP-like immunoreactivity was observed within neurons and intraganglionic nerve fibers in all kinds of enteric plexuses as well as within nerves in the circular muscular layer and mucosa, what is in accordance with previous studies in various species, including humans [18][19][20][21][22][23][24][25]41,42].…”

“…Till now SP-like immunoreactivity has been observed in various fragments of the GI tract of numerous mammals both in enteric neurons within all types of intramural plexuses, as well as in nerve processes that innervate intestinal muscles and submucosal and mucosal layers [18][19][20][21][22][23][24][25]. SP in the GI tract can play multiple roles according to the species, fragment of the GI tract and type of stimulated receptor .…”

Intrinsic Innervation of the Persian Squirrel (Sciurus anomalus) Ileum

“…Enteric neurones containing SP seem to be involved in the regulation of epithelial secretion and motility in the rat intestine (Mitsui, ) and guinea pig (Cooke et al., ; Johnson et al., ; Weber et al., ).…”

“…Most morphological, electrophysiological and neurochemical investigations on the ENS have been carried out on laboratory rodents such as the guinea pig (Mawe et al., ; Quinson et al., ; Furness et al., ), mouse (Qu et al., ; Mongardi Fantaguzzi et al., ), rat (Sayegh and Ritter, ; Mitsui, , ), hamster (Toole et al., , ), but also on some domestic large mammals such as the horse (Domeneghini et al., ; Freytag et al., ; Chiocchetti et al., ; Russo et al., ), pig (Brehmer and Stach, ; Brehmer et al., , ; Balemba et al., ), dog (Furness et al., ; Sternini et al., ), cat (Kleinschmidt et al., ), sheep (Chiocchetti et al., ; Pfannkuche et al., ; Mazzuoli et al., , ), and other small mammals, such as the rabbit (Gábriel et al., ; Dénes and Gábriel, ) and ferret (Sann et al., ), considering, at present, the latter species as domestic animals.…”

The influence of ileitis on the neurochemistry of the caudal mesenteric ganglion in the pig

“…[43][44][45] However, an apparent decrease of the density of CGRP-positive nerve fibers suggests that the origin of SP-and CGRP-positive nerve fibers must be, in majority, different. SP 46 and CGRP 47 are present in the intrinsic primary sensory neurons of the gut, understood, however, to play role in reflex arcs formation at the level of the intestinal wall. These neurotransmitters were also found in intestinal viscerofugal neurons projecting to CaMG in the dog.…”