The enteric nervous system : new developments and emerging concepts

The enteric nervous system (ENS) is an integrative neuronal network, organized in two ganglionated plexuses, myenteric and submucosal, composed of neurons and enteric glial cells, controlling the activity of the smooth muscle of the gut, mucosal secretion and blood flow. The ENS contains as many neurons as the spinal cord, and the functional and chemical diversity of enteric neurons closely resembles that of the central nervous system. This highly integrated neural system is also referred to as the ‘brain-in-the-gut’, because of its capability to function in the absence of nerve inputs from the central nervous system.peer-reviewe

The enteric nervous system : new developments and emerging concepts

The enteric nervous system (ENS) is an integrative neuronal network, organized in two ganglionated plexuses, myenteric and submucosal, composed of neurons and enteric glial cells, controlling the activity of the smooth muscle of the gut, mucosal secretion and blood flow. The ENS contains as many neurons as the spinal cord, and the functional and chemical diversity of enteric neurons closely resembles that of the central nervous system. This highly integrated neural system is also referred to as the ‘brain-in-the-gut’, because of its capability to function in the absence of nerve inputs from the central nervous system.peer-reviewe

Enteric Nervous System: a Review

DergiPark: 379003tmsjEnteric nervous system directs and regulates the breakdown, absorption and elimination of food in our digestive system. However, alongside its digestive functions, enteric nervous system has also gained importance because of the discovery of its bidirectional link with intestinal flora, which has recently started to be considered as a separate organ in addiction to its digestive functions. Enteric nervous system contains approximately 100 million nerve cells, operates both independently and in coordination with the central nervous system, interacts with many neurotransmitters and is related to many conditions and structures such as the intestinal flora, mood, immune system and the efficiency of food utilization. It has a clinical importance on account of the diseases it is associated with. Recent studies focus on the connections between the intestinal flora, enteric nervous system and mechanisms of disease development. In order to understand these studies and pathological mechanisms it is essential to know the structure, connections and functioning of enteric nervous system. Considering these, we addressed the enteric nervous system and its communications with other structures of the digestive syste

Prenatal development of the myenteric plexus in the human fetal small intestine

The enteric nervous system is large, complex and independent of the central nervous system. Its neuralcrest-derived precursors migrate along defined pathways to colonize the bowel. It has been established that signalling molecules produced by the developing neurons and the mesenchyma of the gut wall play a critical role in the development of the mammalian enteric nervous system. Recent studies have further characterized the roles of the different cellular and molecular elements that are critical for enteric ganglia formation. The application of modern neuroanatomical techniques revealed that the enteric nervous system contains a considerable number of neuronal subpopulations. Most of our knowledge concerning the functional features of the enteric neurons, e.g. chemical coding, neuronal connectivity and electrophysiological behaviour, was derived from studies of the guinea-pig small intestine. In light of the interspecies differences, comparison of the findings on different species is mandatory. Consequently, the investigation of human fetal material is necessary in order to estab-lish the basic rules of the development of the human enteric nervous system and to find the time relation between the morphological and functional maturation, thereby permitting an understanding of the causes of congenital malformation leading to misfunction of the gastrointestinal system

Morphological changes in the enteric nervous system caused by carcinoma of the human large intestine.

The innervations of the large intestine is responsible for it peristalsis and contractibility. Investigations of the enteric nervous system in many colon diseases have revealed changes in this structure. No study has been carried out on morphological changes of the enteric nervous system in the human large intestine with carcinoma. The aim of this study was to investigate potential changes in the structure of the enteric neurons in patients with sigmoid and rectal cancer. Material for the study was obtained from patients undergoing operations due to carcinoma of the sigmoid colon and rectum. Microscopic observation of the cancerous tumor of the human large intestine revealed changes in the enteric nervous system innervating this part of the gastrointestinal tract. In the region of the enteric plexuses located close to the tumour, disruption of their correct placement and structure was observed. The changes also consisted of the disappearance of neurons and nerve fibers forming these plexuses. In the solid cancerous tumour, elements of the enteric nervous system were not present. Destruction of the enteric nervous system in the course of carcinoma of the large intestine may cause disruption of proper intestinal function and may be responsible for part of symptoms which the patients suffer

Interaction between <i>Mycobacterium tuberculosis</i>, <i>Mycobacterium bovis</i>, <i>Mycobacterium avium</i> subspecies <i>paratuberculosis</i> with the enteric glia and microglial cells

Background We investigated the interaction of Mycobacterium avium subspecies paratuberculosis, M. bovis and M. tuberculosis and different glial cells (enteric glial and microglial cells) in order to evaluate the infecting ability of these microorganisms and the effects produced on these cells, such as the evaluation of cytokines expression. Results Our experiments demonstrated the adhesion of M. paratuberculosis to the enteroglial cells and the induction of IL-1A and IL-6 expression; M. tuberculosis and M. bovis showed a good adhesive capability to the enteric cell line with the expression of the following cytokines: IL-1A and IL-1B, TNF-α, G-CSF and GM-CSF; M. bovis induced the expression of IL-6 too. The experiment performed with the microglial cells confirmed the results obtained with the enteroglial cells after the infection with M. tuberculosis and M. bovis, whereas M. paratuberculosis stimulated the production of IL-1A and IL-1B. Conclusion Enteroglial and microglial cells, could be the target of pathogenic mycobacteria and, even if present in different locations (Enteric Nervous System and Central Nervous System), show to have similar mechanism of immunomodulation

Ancient evolutionary origin of vertebrate enteric neurons from trunk-derived neural crest

The enteric nervous system of jawed vertebrates arises primarily from vagal neural crest cells that migrate to the foregut and subsequently colonize and innervate the entire gastrointestinal tract. Here we examine development of the enteric nervous system in the basal jawless vertebrate the sea lamprey (Petromyzon marinus) to gain insight into its evolutionary origin. Surprisingly, we find no evidence for the existence of a vagally derived enteric neural crest population in the lamprey. Rather, labelling with the lipophilic dye DiI shows that late-migrating cells, originating from the trunk neural tube and associated with nerve fibres, differentiate into neurons within the gut wall and typhlosole. We propose that these trunk-derived neural crest cells may be homologous to Schwann cell precursors, recently shown in mammalian embryos to populate post-embryonic parasympathetic ganglia, including enteric ganglia. Our results suggest that neural-crest-derived Schwann cell precursors made an important contribution to the ancient enteric nervous system of early jawless vertebrates, a role that was largely subsumed by vagal neural crest cells in early gnathostomes

Effect of Exercise on Enteric Nervous System and the Dysfunction of Colon in Type 2 Diabetes Rat

[Objective] Enteric nervous system (ENS), as a local nervous system, is relatively independent to ectogenic innervation of gastrointestinal tract. This study would observe the effect of aerobic exercise and dietary patterns on enteric function in type Ⅱdiabetes rats and analyze its enteric nervous mechanism. [Methods] The rat model of Type 2 diabetic was induced by feeging high lipid food and injection of streptozotocin (30mg/kg, i.p.), and the rats were divided into 4 groups: diabetes control group (DC), high fat dietgroup (HFD), exercisegroup (E) and exercise combined with high fat diet group（E+HFD）. Some other healthy rats were arranged into normal control group (NC). The rats in E group and E+HFD group performed 8-week swimming training (5 times/week, 60 min/time ). The colon Samples were collected at the end of 8th week for observation of the pathological changes by HE staining , transmission electron microscope (TEM) and for detection of colonic tension and expression of PGP9.5, SP and VIP. [Results] 1) Diabetes induced significant myenteric plexus damages and marked neurons reduction, while exercise protected the enteric nervous system from injuries(Figure1); 2) The expression of SP significantly increased in rats with long-term aerobic exercise combined with a reasonable diet. However, high-fat diet combined with exercise can not upregulate SP obviously; 3) The positive expression of VIP in colon significantly increased in both E group and E+HFD group; 4) Aerobic exercise attenuated atrophy and increased tension in colonic smooth muscles. [Conclusion] Diabetes induces muscular atrophy and tension attenuation in colonic smooth muscle, which can be reversed in some extent by aerobic exercise through the remolding of enteric nervous system

Effects of the Autonomic Nervous System, Central Nervous System and Enteric Nervous System on Gastrointestinal Motility

The gastrointestinal tract is chiefly involved in the digestion of ingested food, facilitation of absorption process and expulsion of the undigested food material through motility process. Motility is influenced by neurohormonal system which is associated with the enteric nervous system , autonomic nervous system and the higher centres in the brain. Many GIT diseases are characterized by altered function of the neurohormonal system associated with it, leading to various functional disorders. Characterization of various physiological factors involved in motility may lead to the development of specific drugs which may either enhance or decrease motility in various pathological conditions. A number of clinically used drugs including metoclopromide, cisapride and domperidone alter gastrointestinal motility via the modification of neurohormonal system. Targets need to be identified in several places in the enteric nervous system to normalize the deranged activity of gastrointestinal tract. The ultimate goal in managing patients with gastrointestinal disorders is to relieve symptoms and thereby improve the quality of life. In this review article, an exhaustive literature search was carried out to reveal the potential of important physiological systems that regulate gastrointestinal motility.Keywords: Enteric nervous system, Intestine, gut, autonomic nervous systemEast and Central African Journal of Pharmaceutical Sciences Vol. 13 (2010) 50-5

Blood-nervous Tissue Barriers In The Peripheral Nervous System

After years of investigation into blood-nervous tissue barriers controversies remain regarding the permeability of blood vessels to macromolecules in the enteric nervous system, the endoneurium of peripheral nerve, and the spaces between satellite cells and neurons in sensory and sympathetic ganglia.;The permeability of the above areas of the peripheral nervous system was investigated in rats using the following intravenously administered tracers: rhodamine-labelled bovine albumin; horseradish peroxidase; acriflavine and ethidium. The last two, which are fluorescent cationic dyes were shown to bind to serum proteins. In addition immunohistochemical staining for endogenous albumin was performed. One long-term study was done in which rhodamine-labelled bovine albumin was injected subcutaneously, once daily, for one week. With all these methods, it was possible to show that blood vessels in the brain were impermeable, whereas those in circumventricular organs were permeable, thus validating their application to regions in which the existence of permeable vessels was questionable.;Rhodamine-labelled bovine albumin was seen in all the extracellular spaces in sympathetic and sensory ganglia, even after short times in the circulation. The endoneurium of peripheral nerve contained this tracer only in rats in which it had been injected daily for one week. At no time did this fluorescent albumin enter the enteric ganglia. Positive immunohistochemical staining for endogenous albumin was present in the enteric nervous system, in the endoneurium of peripheral nerve, in the spaces between satellite cells and neurons in sensory ganglia, and around neurons in sympathetic ganglia. Horseradish peroxidase, which is present in the blood for about 5 minutes following intravenous injection, penetrated the enteric nervous system, and the extracellular spaces between satellite cells and neurons in sensory ganglia, but it did not enter the endoneurium of peripheral nerve. The fluorochromes acriflavine and ethidium entered enteric, sympathetic and sensory ganglia, but not the endoneurium of peripheral nerve.;In conclusion, the enteric nervous system, sympathetic and sensory ganglia are permeable to most circulating macromolecules. The endoneurium of peripheral nerve is permeable only to macromolecules that are present in the circulation for at least one week, so the transudation or diffusion in this tissue must occur more slowly than elsewhere. These permeabilities may explain how some pathogens enter the nervous system