== Time course of the effects of partial restraint stress on CRF peptide levels in the rat colon

== Time course of the effects of partial restraint stress on CRF peptide levels in the rat colon. as a control (dsControl). Four Anisomycin days after dsRNA injection, rats were subjected to 1-h PRS. Fecal output was assessed. Ussing chamber techniques were used to assess colonic mucosal ion secretion and transepithelial tissue conductance. == Important Results == Exposure to PRS elevated CRF expression and increased CRF release in the rat digestive tract. Injection of dsCRF inhibited basal CRF expression and prevented the PRS-induced increase in CRF manifestation, whereas CRF expression in dsControl-injected colons remained large after PRS. In rats treated with dsControl, PRS caused a significant increase in fecal pellet output, colonic baseline ion secretion, and transepithelial tissue conductance. Inhibition of CRF manifestation in the digestive tract prevented PRS-induced increase in fecal output, baseline ion secretion, and transepithelial tissue conductance. == Findings & Inferences == These results offer direct proof that transient perturbation in peripherally expressed CRF prevents colonic responses to stress. Keywords: stress, digestive tract, CRF, motility, ion secretion == LAUNCH == Corticotropin releasing element (CRF) is important for our bodys overall responses to stress. (1) Besides CRF, three other CRF-related peptides, urocortin (Ucn)1, Ucn2, and Ucn3, have been determined in mammals. (24) CRF and Ucns exert their biological actions via two CRF receptor subtypes, CRF1and CRF2. (5) CRF signaling in the brain has been known to mediate colonic responses to stress. Exposure to a range of acute stressors stimulates colonic motor activity. (612) Intracerebral or intraventricular administration of CRF or Ucn1 simulates the effects of acute stress by enhancing colonic motility. (6, 7, 1315) Intracerebral injection of non-selective peptide CRF receptor antagonists or selective CRF1antagonists inhibits the effects of both acute stress and CRF/Ucn1 on colonic motor activity. (6, 7, 11, 1316) However , intracerebral administration from the CRF2-specific peptide antagonists does not inhibit stress or CRF-induced acceleration of colonic motility and transit. (11) These findings implicate the central CRF/CRF1signaling pathway in mediating the colonic motor responses to acute stress. Besides the brain, CRF peptides and CRF receptors are also found in the gut. We recently reported the expression of CRF/UCNs and their receptors in the enteric nervous system (ENS) from the rat and guinea pig gastrointestinal tract. (1721) In guinea pig, the numbers of enteric neurons that express immunoreactivity to get CRF increase progressively in the aboral direction, with the cheapest numbers found in the stomach and the largest numbers in the distal digestive tract. (18) CRF and Ucn1 cause excitation of myenteric neurons via activating CRF1. (17, 19, 22) CRF, CRF1, and CRF2are also expressed in enterochromaffin cells, mononuclear cells, macrophages, and mast cells in the digestive tract. (2330) When injected peripherally, CRF enhances colonic motility in rodents and humans. (3134) Peripherally injected non-selective peptide CRF receptor antagonists or selective CRF1antagonists obstruct the activation of colonic motility induced by acute stress or peripheral injection of CRF. (6, 32, Anisomycin 34) Peripheral activation of CRF2by intraperitoneal (ip) injection of Ucn2 reduces acute stress or CRF-induced defecation and colonic motility in rodents; whereas ip injection Anisomycin of astressin2-B, a peptide CRF2antagonist, enhances stress-induced increase in colonic motility. (35) These observations suggest that activation of peripheral CRF1contributes to stress-related stimulation of colon motility, whereas activation of peripheral CRF2counteracts the CRF1-mediated activation of colonic motility and initiates a stress coping response in rodents. Stress greatly enhances intestinal ion secretion and disrupts intestinal epithelial hurdle. Psychological stress has been discovered to increase Na+and Clsecretion and reduce H2O absorption in human being jejunum. (36) Restraint stress has been discovered to stimulate watery diarrhea in rats. (37) Similarly, ip injection of CRF increases colonic baseline ion secretion and evokes watery diarrhea in rats, which is mimicked by peripheral injection of cortagine, a selective CRF1agonist, (38) and antagonized by the selective CRF1antagonists. (39, 40) Peripherally applied CRF increases intestinal epithelial permeability for large organic molecules in human being colon mucosal biopsies. (41) Pretreatment Rabbit polyclonal to ZCCHC12 with -helical CRF941, a non-selective peptide CRF receptor antagonist, abolished the actions of CRF on colonic mucosal permeability. (41) The evidence implicates that CRF signaling takes place locally in the gut and affects colonic motility and secretion. However , no research has been done to determine the role of endogenous CRF in the gut in colonic responses to stress. We therefore aimed to check out if transient perturbation in expression of endogenous CRF in the gut is sufficient to change stress-induced colonic motor and secretory responses. Preliminary reviews of the results have been released in fuzy form. (42, 43) == MATERIALS AND METHODS == == Animals == Adult Sprague-Dawley rats (male, 250275 g) were purchased coming from Charles River, Wilmington, MA, USA, housed in the University of Wisconsin-La Crosse and/or University of California San Francisco (UCSF) dog facility at 22C with a 12-h light/12-h dark routine, and had totally free access to food and tap water. The animal treatment and experimental.