Table 1.

Studies Showing the Effect of Stress/Corticotropin-releasing Factor on Intestinal Permeability

Author	Permeability assessment methods	Stress model	Results
Santos et al,37 1999	Ussing chambers measuring conductance (G), short-current circuit (Isc) and horseradish peroxidase (HRP) flux in rat colon	Restraint stress and corticotrophin-releasing factor (CRF) administration	Restraint stress increased colonic ion secretion and permeability to ions, bacterial peptide peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP), and HRP. These changes were prevented by alpha-helical CRF9–41 and mimicked by CRF administration. Pre-treatment with hexamethonium, bretylium and doxantrazole also prevented CRF-induced changes in ion secretion and G.
Saunders et al,33 2002	Ussing chambers measuring G, and HRP flux in rat colon	Cold-restraint and water avoidance stress (WAS), and CRF administration	Cold-restraint stress, and WAS significantly elevated G and HRP flux. CRF mimicked the stress responses. Alpha-helical CRF9–41 inhibited the stress-induced abnormalities.
Guilarte et al,164 2004	Albumin release to the intestinal lumen in healthy volunteers and irritable bowel syndrome	CRF administration	CRF induced a significant increase in albumin release to the intestinal lumen.
Gareau et al,180 2006	Ussing chambers measuring G, and Isc in rat colon	Neonatal maternal separation.	Neonatal maternal separation stress increased plasmatic corticosterone, enhanced ion secretion, macromolecular permeability, bacteria adhering, and penetration into the colonic epithelium. Alpha-helical CRF9–41 reversed stress-induced effects.
Yang et al,82 2006	Ussing chambers measuring G, Isc and HRP flux in rat jejunum	WAS and oral HRP sensitization	Antigen challenge induced a rapid ion secretory response and an increase in G only in rats submitted to WAS. These effects were reversed by alpha-helical CRF9–41.
Gareau et al,78 2007	Ussing chambers measuring HRP flux in rat colon	Neonatal maternal separation	Neonatal maternal separation stress increased HRP flux. The enhanced flux was inhibited by atropine and hexamethonium. Alpha-helical CRF9–41 and antisauvagine-30 inhibited stress-induced increase in HRP flux.
Santos et al,59 2008	Ussing chambers measuring Isc and HRP flux in rat colon	CRF and sauvagine exposure	Sauvagine and CRF induced a dose-dependent increase in Isc and HRP flux and an enhancement in protease II pre-treatment with astressin, and doxantrozole inhibited this response. Mast-cell deficient mice displayed a reduced epithelial response to stress peptides.
Teitelbaum et al,57 2008	Ussing chambers measuring G, Isc and HRP flux in rat colon	CRF administration	Chronic CRF administration increased Isc, G, and HRP flux, but not in mast-cell deficient rats. CRF administration induced mast cell hyperplasia and abnormal bacterial attachment into the mucosa that was absent in mast-cell deficient rats.
Alonso et al,65 2008	Albumin release to the intestinal lumen in healthy volunteers	Cold Pain Stress	Cold pain stress induced a significant increase in albumin release to the intestinal lumen.
Wallon et al,68 2008	Ussing chambers measuring Isc, HRP flux, 51Cr-EDTA, and transepithelial resistance (TER) in human colon	CRF administration	CRF increased permeability to HRP. The increased permeability to HRP was abolished by alpha-helical CRF9–41, and lodoxamide pre-treatment.
Larauche et al,48 2009	Evans blue extravasation in rat colon	Cortagine administration	Cortagine induced a significantly increased intestinal permeability. Astressin-B abolished the cortagine-induced increase in intestinal permeability.
Zheng et al,102 2009	Ussing chambers measuring Isc, HRP flux, and TER in mouse jejunum	Restraint stress and substance P (SP) exposure	SP stimulation induced a significant increase in Isc and HRP flux in stressed mice. Those changes were lower in mast cell-deficient mice. Alpha-helical CRF9–41, inhibited SP-induced intestinal barrier dysfunction.
Smith et al,58 2010	Ussing chambers measuring Isc, 3H mannitol flux, 14C inulin flux, and TER in pig jejunum and colon	Early weaning	Early weaning reduced jejunal TER and enhanced Isc and mucosal-to-serosal flux of 3H mannitol and 14C inulin in association with increased lamina propria mast cell density. Sodium cromoglycolate ameliorated barrier dysfunction and hypersecretion in early-weaned pigs. C48/80 and CRF exposure increased Isc and induced intestinal barrier dysfunction that were inhibited with mast cell protease inhibitors.
Keita et al,181 2010	Ussing chambers measuring G, Isc, HRP flux, 51Cr-EDTA, and Escherichia coli K-12 flux in rat follicle-associated epithelium (FAE) and villus epithelium (VE) from rat ileum	WAS	WAS increased G, Isc, HRP and E. Coli uptake in FAE and VE. SP increased bacterial and 51Cr-EDTA intestinal permeability. These results were mimicked by CRF and carbachol and reduced by doxantrazole, CRF receptor antagonist and atropine.
Wallon et al,83 2011	Ussing chambers measuring Isc, HRP flux, 51Cr-EDTA, fluorescein isothiocyanate (FITC)-Dextran 4000, and TER in non inflamed human colon biopsies from ulcerative colitis patients	None	HRP flux, TER, and Isc were increased in mucosa from patients with UC. Alpha-helical CRF9–41, atropine and lodoxamide reversed the increase in intestinal permeability.
Alonso et al,111 2012	Albumin release to the intestinal lumen in healthy volunteers	Cold Pain Stress	Cold pain stress induced a significant increase in albumin release to the intestinal lumen.
Ait-Belgnaoui et al,182 2012	Ussing chambers measuring FITC-Dextran flux in rat colon	Partial restraint stress	Stress increased plasma ACTH and corticosterone, and hypothalamic CRF and enhanced colonic paracellular permeability. Probiotic treatment prevented stress-induced increased intestinal permeability.
Overman et al,87 2012	Ussing chambers measuring FITC-Dextran flux in porcine ileum	CRF exposure	CRF increased paracellular FITC-Dextran flux. Pre-treatment with astressin-B, sodium cromolyn, anti-TNF-α antibodies, protease inhibitors, and tetrodotoxin inhibited CRF-mediated intestinal barrier dysfunction.
Vicario et al,53 2012	Ussing chambers measuring G and Isc in rat colon	Crowding stress and CRF administration	Crowding stress significantly increased G and Isc and CRFR1 in the rat colon. CRF administration mimicked stress-induced epithelial dysfunction.
Hill LT et al,183 2013	Lactulose-mannitol urinary excretion test in shocked patients undergoing small bowel resection during emergency laparotomy and patients undergoing elective hepatobiliary surgery	Shock and abdominal surgery	Shock was associated with increased intestinal permeability. Plasma CRF was significantly increased in the shocked patients.
Yu et al,81 2013	HRP flux and TER in HT-29, T84, MDCK, and Caco2 monolayers Ussing chambers measuring G, Isc, and HRP flux in mouse colon	CRF exposure and WAS	WAS increased G and Isc and HRP flux, and this increase was higher after LPS stimulation. This response was abolished by pre-treatment with anti-claudin 2 (Cldn2) antibodies. Stress also increased the expression of Cldn2 and toll-like receptor-4 (TLR4) in mouse epithelium. Exposure to CRF induced Cldn2 and TLR4 expression in intestinal epithelial cells.
Vanuytsel et al,38 2014	Lactulose-mannitol urinary excretion test in healthy volunteers	Indomethacin administration, public speech, CRF administration, and electroshock anticipation	Public speech and CRF administration increased intestinal permeability and salivary cortisol. Increased permeability after public speech was only present in subjects with a significant elevation of cortisol. Pre-treatment with disodium cromoglycate inhibited stress and CRF-induced increased intestinal permeability.