The Enteric Nervous System

Nearly 30 years ago, a number of scientists working on the Enteric Nervous System (ENS) gathered at Flinders University, in Adelaide, Australia to discuss the advances and future of their research. It was a friendly and stimulating meeting, attended by most of the major players, in what was to become the discipline of ‘Neurogastroenterology'. In 2014, the main Australasian Neuroscience Society meeting was held in Adelaide, Australia, providing the perfect opportunity to recreate a follow-up ENS meeting. As such, the ‘ENS II 2014 meeting’ aimed to identify how far the field of enteric neuroscience had developed, where the future was heading, and what technological advances had been made to address current and future unresolved questions. 30 speakers from around the world were invited to give talks and revisit the original expectations, the advances made since, and the future directions of ENS research. These discussions included three generations of investigators from 7 different countries. This publication represents the majority of proceedings from the ‘The Enteric Nervous System II 2014’ conference, which was held on February 1st - 2nd 2014 at the National Wine Centre of Australia, Adelaide. This meeting was an Official satellite meeting of the 34th Annual Meeting of Australasian Neuroscience Society, which was also held in Adelaide. The 20 contributions contained within this submission are from international researchers in the field of the ENS, who reviewed the advances made since the first meeting in the early 1980s and summarizes the present and future perspectives of neuro-gastroenterology. Some colleagues could not attend but did send greetings and their messages are included in these proceedings.

The enteric nervous system (ENS) is a complex neural network embedded in the gut wall that orchestrates the reflex behaviors of the intestine. The ENS is often referred to as the “little brain” in the gut because the ENS is more similar in size, complexity and autonomy to the central nervous system (CNS) than other components of the autonomic nervous system. Like the brain, the ENS is composed of neurons that are surrounded by glial cells. Enteric glia are a unique type of peripheral glia that are similar to astrocytes of the CNS. Yet enteric glial cells also differ from astrocytes in many important ways. The roles of enteric glial cell populations in the gut are beginning to come to light and recent evidence implicates enteric glia in almost every aspect of gastrointestinal physiology and pathophysiology. However, elucidating the exact mechanisms by which enteric glia influence gastrointestinal physiology and identifying how those roles are altered during gastrointestinal pathophysiology remain areas of intense research. The purpose of this e-book is to provide an introduction to enteric glial cells and to act as a resource for ongoing studies on this fascinating population of glia. Table of Contents: Introduction / A Historical Perspective on Enteric Glia / Enteric Glia: The Astroglia of the Gut / Molecular Composition of Enteric Glia / Development of Enteric Glia / Functional Roles of Enteric Glia / Enteric Glia and Disease Processes in the Gut / Concluding Remarks / References / Author Biography

This book first presents an overview on the chemical coding of the morphological neuron types described by Stach in the pig intestine. In doing so, we have pointed out the difference between the definitions of type I neurons given by Dogiel and Stach. Secondly, it provides a basis for the morpho-chemical classification of human enteric neurons as revealed by their immunoreactivity for neurofilaments and several neuroactive substances or related markers.

Up-to-date reviews on the mechanisms of gastrointestinal injury and protection In recent years, there have been significant advances both in understanding the mechanisms involved in gastrointestinal mucosal injury and protection, as well as in the development of successful strategies for prevention and treatment of gastrointestinal injury. Nevertheless, many people worldwide still suffer from gastrointestinal damage. This book contains contributions by an international panel of researchers in the form of up-to-date reviews on the mechanisms of gastrointestinal injury and protection. These are complemented by papers discussing how these new findings about cell/tissue injury and cytoprotection/organoprotection can be applied to the prevention and treatment of tissue damage in the gastrointestinal tract. Moreover, the publication includes a special chapter on Andre Robert, who has discovered the phenomenon of gastric cytoprotection. This publication will be of great interest for both basic and clinical researchers in gastroenterology and pharmacology, reviewing the advances made so far and pointing towards future developments.

Covers all aspects of the structure, function, neurochemistry,transmitter identification and development of the enteric nervoussystem This book brings together extensive knowledge of the structureand cell physiology of the enteric nervous system and provides anup-to-date synthesis of the roles of the enteric nervous system inthe control of motility, secretion and blood supply in thegastrointestinal tract. It includes sections on the enteric nervous system in disease,genetic abnormalities that affect enteric nervous system function,and targets for therapy in the enteric nervous system. It alsoincludes many newly created explanatory diagrams and illustrationsof the organization of enteric nerve circuits. This new book is ideal for gastroenterologists (includingtrainees/fellows), clinical physiologists and educators. It isinvaluable for the many scientists in academia, research institutesand industry who have been drawn to work on the gastrointestinalinnervation because of its intrinsic interest, its economicimportance and its involvement in unsolved health problems. It alsoprovides a valuable resource for undergraduate and graduateteaching.

Minute-to-minute behavior of the alimentary tract reflects the integrated functioning of the gut's musculature, secretory glands and blood–lymphatic vasculature. Activity of the three effector systems to generate functionally effective patterns of behavior, which are adaptive for differing digestive states, is organized and coordinated by the enteric nervous system (i.e., the brain-in-the-gut). The heuristic model for the enteric nervous system (ENS) is the same as for all integrative nervous systems, whether in vertebrate or invertebrate animals. Like other integrative nervous systems, such as the spinal cord and brain stem, the ENS functions with sensory neurons, interneurons and motor neurons. That the gut does not work without the ENS can be made as an absolute statement. This is apparent in its absence in terminal regions of the large intestine in Hirschsprung's disease in humans and animals where it is reflected by dysfunctional motility, failure of defecation and proximal fecal compaction within a proximal megacolon. Autoimmune ablation of the ENS in the lower esophageal sphincter underlies the pathophysiology of achalasia. Furthermore, neuropathic degeneration of ENS neurons in irritable bowel syndrome, other functional gastrointestinal disorders, intestinal pseudoobstruction, Chagas disease, paraneoplastic syndrome and enteric ganglionitis, underlies the morbidity associated with these disorders. The impact of these clinical disorders on quality of life and cost of health care is a reminder of the importance of the ENS for a normally functioning gut. Moreover, our incomplete understanding of the pathobiology of these disorders highlights a need for research directed to expansion of current knowledge of the neurobiology of the ENS at all levels of organization from the cellular biology of individual neurons to the biophysics of integrated networks to whole organ behavior. Investigation of the normal and disordered ENS and its interactions with the central nervous system is a branch of neurogastroenterology. Neurogastroenterology is a scientific and clinical subspecialty of gastroenterology that deals with the neural mechanisms that influence function of the digestive tract and that underlie projection of conscious sensations to the gut. Table of Contents: Introduction / Historical Perspective / Heuistic Model / Microanatomy / Sensory Neurophysiology / Interneurons / Enteric Motor Neurons / Disinhibitory Motor Disorders / Neuronal Electrical Behavior / Synaptic Transmission / Organ Level Integration / Gastric Motor Integration / Integrated Control of the Small and Large Intestines / Plasticity in the ENS / Small Intestine Motility / Defecation / References