Role of peripheral CRF signalling pathways in stress-related alterations of gut motility and mucosal function.

Central corticotrophin releasing-factor (CRF) signalling pathways are involved in the endocrine, behavioural and visceral responses to stress. Recent studies indicate that peripheral CRF-related mechanisms also contribute to stress-induced changes in gut motility and intestinal mucosal function. Peripheral injection of CRF or urocortin inhibits gastric emptying and motility through interaction with CRF2 receptors and stimulates colonic transit, motility, Fos expression in myenteric neurones and defecation through activation of CRF1 receptors. With regard to intestinal epithelial cell function, intraperitoneal CRF increases ion secretion and mucosal permeability to macromolecules. The motility and mucosal changes induced by peripheral CRF mimic those induced by acute stress. In addition, CRF receptor antagonists given peripherally prevent acute restraint and water avoidance stress-induced delayed gastric emptying, stimulation of colonic motor function and mucosal permeability. Similarly, early trauma enhanced intestinal mucosal dysfunction to an acute stressor in adult rats and the response is prevented by peripheral injection of CRF antagonist. Chronic psychological stress results in reduced host defence and initiates intestinal inflammation through mast cell-dependent mechanisms. These findings provide convergent evidence that activation of peripheral CRF receptors and mast cells are important mechanisms involved in stress-related alterations of gut physiology.