Quantitative morphometric analysis of the myenteric nervous plexus ganglion structures along the human digestive tract.

BACKGROUND/AIM: All the functions of the digestive system are controlled, guided and initiated by the autonomic nervous system. A special part of this system placed in the wall of the gastrointestinal tract is known as the enteric or metasympathetic nervous system. The aim of this study was to analyse myenteric nervous plexus in different parts of the digestive tract. METHODS: We examined the myenteric nervous plexus of the esophagus, stomach, duodenum, jejunum, ileum, transverse colon and rectum in tissue samples taken from 30 cadavers of persons aged 20-84 years. After standard histological processing sections were stained with hematoxylin-eosin, cresyl violet (CV) and AgNO3 method. Multipurpose test system M42 was used in morphometric analysis. The results were analyzed by t-test and analysis of variance. RESULTS: The number of neurons per cm² surface was the lowest in the esophagus (2.045 ± 310.30) and the largest in the duodenum (65,511 ± 5,639). The statistical processing showed significant differences (P < 0.001) in the number of neurons between the esophagus and all other parts of the digestive tract. The maximal value of the average surface of the myenteric nervous plexus neurons was observed in the esophagus (588.93 ± 30.45 µm²) and the lowest in the stomach (296.46 ± 22.53 µm²). CONCLUSION: There are differences in the number of ganglion cells among different parts of the human digestive tract. The differences range from a few to several tens of thousands of neuron/cm2. The myenteric nervous plexus of the esophagus was characterized by a significantly smaller number of neurons but their bodies and nuclei are significantly larger compared to other parts of the digestive tract.

Co-localisation of cocaine- and amphetamine-regulated transcript peptide and vasoactive intestinal polypeptide in the myenteric plexus of the porcine transverse colon.

Cocaine- and amphetamine-regulated transcript peptide (CART) is a substance,which can play the role of neuromediator and/or neuromodulator in nerve structures within the gastrointestinal tract. However knowledge concerning its functions and co-localisation with other neuronal factors is rather scarce. During the present investigation the co-localisation of CART and vasoactive intestinal polypeptide (VIP) in the neurons of meyenteric plexus within the porcine transverse colon was studied using double immunofluorescence technique and semiquantitative arbitrary scale of the frequency of presence CART+/VIP+, CART+/VIP- and CART-/VIP+ neuronal cells. The most often (+++) CART-/VIP+ neurons were encountered, neurons simultaneously immunoreactive to CART and VIP were observed somewhat rarer (++) and only single (+) CART+/VIP- perikarya were visible. The present study reports for the first time on the co-localisation of CART and VIP in myenteric neurons of the porcine transverse colon.

Relaxin exerts two opposite effects on mechanical activity and nitric oxide synthase expression in the mouse colon.

The hormone relaxin exerts a variety of functions on the smooth muscle of reproductive and nonreproductive organs, most of which occur through a nitric oxide (NO)-mediated mechanism. In the stomach and ileum, relaxin causes muscle relaxation by modulating the activity and expression of different nitric oxide synthase (NOS) isoforms region-dependently. Nothing is known on the effects of relaxin in the colon, the gut region expressing the highest number of neuronal (n) NOSß-immunoreactive neurons and mainly involved in motor symptoms of pregnancy and menstrual cycle. Therefore, we studied the effects of relaxin exposure in the mouse proximal colon in vitro evaluating muscle mechanical activity and NOS isoform expression. The functional experiments showed that relaxin decreases muscle tone and increases amplitude of spontaneous contractions; the immunohistochemical results showed that relaxin increases nNOSß and endothelial (e) NOS expression in the neurons and decreases nNOSα and eNOS expression in the smooth muscle cells (SMC). We hypothesized that, in the colon, relaxin primarily increases the activity and expression of nNOSß and eNOS in the neurons, causing a reduction of the muscle tone. The downregulation of nNOSα and eNOS expression in the SMC associated with increased muscle contractility could be the consequence of continuous exposue of these cells to the NO of neuronal origin. These findings may help to better understand the physiology of NO in the gastrointestinal tract and the role that the "relaxin-NO" system plays in motor disorders such as functional bowel disease.

Gender differences in reduced substance P (SP) in children with slow-transit constipation.

PURPOSE: Adult slow-transit constipation (STC) occurs predominantly in females and is associated with low numbers of substance P (SP)-containing nerves in colonic circular muscle. AIM: To determine if reduced SP nerves is female predominant in paediatric STC. METHODS: Children with STC were identified from records of more than 600 nuclear transit studies (NTS) and intestinal biopsies done for intractable chronic constipation between November 1998 and March 2009. Colonic seromuscular biopsies collected from hepatic and splenic flexures, and sigmoid colon were processed for immunohistochemistry. Nerve fibre density in circular muscle containing SP was measured qualitatively by a pathologist. RESULTS: Eighty-eight children with chronic constipation had both NTS and intestinal biopsies. Seventy-eight children (52 M; age 2-15.5 years; mean 7.7 years) had STC diagnosed by NTS. SP was reduced in 10/26 girls, but only 11/52 boys. CONCLUSION: In this sample, STC was more common in boys than girls. However, in girls with STC, SP deficiency occurred in 40%, when compared with 20% of boys. During puberty, the percentage of girls with reduced SP decreased, whilst the percentage of boys increased. These results suggest that STC is heterogeneous and that there are some gender differences, the implication of which requires further investigation.

Substance P and vasoactive intestinal peptide are reduced in right transverse colon in pediatric slow-transit constipation.

BACKGROUND: Slow-transit constipation (STC) is recognized in children but the etiology is unknown. Abnormalities in substance P (SP), vasoactive intestinal peptide (VIP) and nitric oxide (NO) have been implicated. The density of nerve fibers in circular muscle containing these transmitters was examined in colon from children with STC and compared to other pediatric and adult samples. METHODS: Fluorescence immunohistochemistry using antibodies to NO synthase (NOS), VIP and SP was performed on colonic biopsies (transverse and sigmoid colon) from 33 adults with colorectal cancer, 11 children with normal colonic transit and anorectal retention (NAR) and 51 with chronic constipation and slow motility in the proximal colon (STC). The percentage area of nerve fibers in circular muscle containing each transmitter was quantified in confocal images. KEY RESULTS: In colon circular muscle, the percentage area of nerve fibers containing NOS > VIP > SP (6 : 2 : 1). Pediatric groups had a higher density of nerve fibers than adults. In pediatric samples, there were no regional differences in NOS and VIP, while SP nerve fiber density was higher in sigmoid than proximal colon. STC children had lower SP and VIP nerve fiber density in the proximal colon than NAR children. Twenty-three percent of STC children had low SP nerve fiber density. CONCLUSIONS & INFERENCES: There are age-related reductions in nerve fiber density in human colon circular muscle. NOS and VIP do not show regional variations, while SP nerve fiber density is higher in distal colon. 1/3 of pediatric STC patients have low SP or VIP nerve fiber density in proximal colon.

Nicotine-induced neurogenic relaxation in the mouse colon: changes with dextran sodium sulfate-induced colitis.

Nicotine has been shown to reduce both tone and muscular activity in the human colon by releasing nitric oxide (NO) from nerves. To our knowledge, however, the effect of nicotine on mouse colon has not been elucidated, and the response in tissue from ulcerative colitis (UC) has not been investigated. We examined nicotine-induced responses in colon from control mice and mice with dextran sodium sulfate (DSS)-induced UC. In controls, bath application of nicotine caused a transient relaxation in longitudinal preparations from the transverse and distal colons but not from the rectum. The response was observed in the presence of bethanechol, abolished by treatment with tetrodotoxin and hexamethonium, and mediated partially (>50%) by the NO pathway. In longitudinal preparations of the distal colon from DSS-treated mice, spontaneous contractions decreased markedly, and nicotine caused contraction without relaxation in half of the preparations tested. Nicotine-induced relaxation in the presence of bethanechol was significantly decreased in the DSS-treated distal colon without changing bethanechol-induced contractions. These data suggest that 1) responses to nicotine differ dependent on colon regions, 2) DSS treatment predominantly caused nicotine-sensitive neurogenic changes in distal colon, and 3) DSS treatment may reverse the direction of nicotine-evoked responses in the colon, in mice.

Parasympathetic innervation of the initial segments of the large intestine in cats.

The locations and morphometric characteristics of efferent parasympathetic neurons in the dorsal motor nucleus of the vagus nerve and the cruciform parasympathetic nucleus of the spinal cord, innervating the area of the ileocecal sphincter and the ascending and transverse segments of the colon, were studied. Horseradish peroxidase solution was injected beneath the serous membranes of these parts of the intestine in urethane-anesthetized cats. After 48 h, animals were subjected to transcardiac perfusion with a fixative mixture and sections of the medulla oblongata and spinal cord were prepared and processed by the Mesulam method. The results showed that all these parts of the large intestine received parasympathetic innervation from neurons in the ventrolateral part of the dorsal motor nucleus, which were uniform in terms of their morphometric characteristics. The number of neurons of this group sending axons to the ileocecal area was greater than the number of neurons innervating the ascending colon. A second group of neurons, which were smaller cells, was located in the same part of the nucleus and innervated the transverse colon. The transverse colon also received innervation from neurons in the cruciform parasympathetic nucleus of the spinal cord.