Neurogastroenterology and motility: at last, an equal partnership

New perspectives in the diagnosis and management of enteric neuropathies

Chronic disturbances of gastrointestinal function encompass a wide spectrum of clinical disorders that range from common conditions with mild-to-moderate symptoms to rare diseases characterized by a severe impairment of digestive function, including chronic pain, vomiting, bloating and severe constipation. Patients at the clinically severe end of the spectrum can have profound changes in gut transit and motility. In a subset of these patients, histopathological analyses have revealed abnormalities of the gut innervation, including the enteric nervous system, termed enteric neuropathies. This Review discusses advances in the diagnosis and management of the main clinical entities--achalasia, gastroparesis, intestinal pseudo-obstruction and chronic constipation--that result from enteric neuropathies, including both primary and secondary forms. We focus on the various evident neuropathologies (degenerative and inflammatory) of these disorders and, where possible, present the specific implications of histological diagnosis to contemporary treatment. This knowledge could enable the future development of novel targeted therapeutic approaches.

Nonruminant Nutrition Symposium: Neurogastroenterology and food allergies

Neurogastroenterology is a subspecialty encompassing relations of the nervous system to the gastrointestinal tract. The central concept is emergence of whole organ behavior from coordinated activity of the musculature, mucosal epithelium, and blood vasculature. Behavior of each effector is determined by the enteric nervous system (ENS). The ENS is a minibrain positioned close to the effectors it controls. The ENS neurophysiology is in the framework of neurogastroenterology. The digestive tract is recognized as the largest lymphoid organ in the body with a unique complement of mast cells. In its position at the "dirtiest" of interfaces between the body and outside world, the mucosal immune system encounters food antigens, bacteria, parasites, viruses, and toxins. Epithelial barriers are insufficient to exclude fully the antigenic load, thereby allowing chronic challenges to the immune system. Observations in antigen-sensitized animals document direct communication between the mucosal immune system and ENS. Communication is functional and results in adaptive responses to circumstances within the lumen that are threatening to the functional integrity of the whole animal. Communication is paracrine and incorporates specialized sensing functions of mast cells for specific antigens together with the capacity of the ENS for intelligent interpretation of the signals. Immuno-neural integration progresses sequentially, beginning with immune detection, followed by signal transfer to the ENS, followed by neural interpretation and then selection of a neural program with coordinated mucosal secretion and a propulsive motor event that quickly clears the threat from the intestinal lumen. Operation of the defense program evokes symptoms of cramping abdominal pain, fecal urgency, and acute watery diarrhea. Investigative approaches to immuno-ENS interactions merge the disciplines of mucosal immunology and ENS neurophysiology into the realm of neurogastroenterology.

Gastrointestinal motility: an academic and research perspective

While, in the past, gastrointestinal motility may have been viewed as a narrow and restricted field, confined to the study of twitches in muscle baths and squiggles on smoke drums, it has, of late and belatedly, entered into the mainstream of gastroenterology and medicine. As a consequence, this field, now more correctly and appropriately described as neurogastroenterology, concerns itself with a vast spectrum of clinical disorders of varying pathophysiology, presentation and management. Never before has this area offered so many opportunities to the budding academician and researcher.