Mechanisms of diarrhea.
Diarrhea is a symptom common to a wide variety of gastrointestinal illnesses, and is an important public health challenge in underdeveloped regions of the world. Normal intestinal absorption is a complex process. Recent research offers new insights into normal physiology and pathophysiology. The role of the enteric nervous system and neurotransmitters in the pathogenesis of diarrhea in inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) is being actively investigated. In patients with IBD, ileal and sigmoid biopsies showed altered transepithelial sodium and fluid transport, specifically from decreased expression of the NHE3, NHERF-1, and NHE1 epithelial Na channel. This results in changes in normal intestinal electroneutral NaCl absorption and may be an additional factor contributing to the diarrhea in patients with IBD. Physiologic studies in humans suggest that primary bile acid malabsorption may be caused by an abnormal feedback system resulting in the increased bile salts, which may explain the watery diarrhea. Finally, the role of zinc in treatment of infectious diarrhea led to studies of its effect on intracellular human enterocyte ion secretion. Understanding such basic mechanisms may lead to better and novel therapies for treatment of diarrhea.
Division of Gastroenterology, Department of Medicine, School of Medicine, Harborview Medical Center, University of Washington School of Medicine, 325 Ninth Avenue, Box 359773, Seattle, WA 98104, USA. surawicz@u.washington.edu
Christina M
CM
Surawicz
D001647:Bile Acids and Salts / Q000378:metabolism*; D003967:Diarrhea / Q000150:complications / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D017615:Enteric Nervous System / Q000378:metabolism; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000378:metabolism; D007408:Intestinal Absorption / Q000502:physiology*; D043183:Irritable Bowel Syndrome / Q000378:metabolism; D010750:Phosphoproteins; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*
D001647:Bile Acids and Salts; D010750:Phosphoproteins; D017923:Sodium-Hydrogen Exchangers; C093376:sodium-hydrogen exchanger regulatory factor