Morphological aspects of ionizing radiation response of small intestine

Knowledge of the acute and late ionizing radiation exposure damage to the g astrointestinal tract, particularly injury of the small intestine, is of gr eat significance in radiotherapy, as is management of accidental radiation exposure. Irradiation (X-ray, neutron, cobalt gamma) induces a series of ev ents in this rapidly renewing tissue resulting in the well-known symptoms o f the gastrointestinal (GI) radiation syndrome, such as GI haemorrhage, end otoxemia, bacterial infection, anorexia, nausea, vomiting, diarrhoea, and l oss of electrolytes and fluid. In spite of the significant advances that ha ve occurred in research on underlying mechanisms over the last two decades, the overall etiology and pathogenesis of the GI-syndrome still remains unc lear. Currently, to our knowledge, these symptoms are probably due to a rap id modification of the intestinal motility and to the structural alteration of the intestinal mucosa (cell loss and altered crypt integrity). Several evidences suggest that radiation-induced dysfunctions and structural change s of this organ (either changes in subcellular, cellular, and histological structure) are mediated by concerted and interrelated changes of a plethora of various extracellular mediators and their intracellular messengers. The aim of this review is to summarize our current knowledge about the pathomo rphology and cell biology of the ionizing radiation response of the GI trac t with a focus on the small intestine. (C) 2001 Elsevier Science Ltd. All l ights reserved.