title: Adrenocorticotrophic hormone modulates Escherichia coli O157:H7 adherence to porcine colonic mucosa.
abstract: Exposure to stress is associated with susceptibility to disease and one stress mediator, norepinephrine, has been reported to enhance the adherence of enterohemorrhagic Escherichia coli O157:H7 (EHEC) to the colonic mucosa. We tested the hypothesis that adrenocorticotropic hormone (ACTH) and other stress-related hormones may act in a similar fashion. Explants of distal colonic mucosa from young pigs were mounted in Ussing chambers and their luminal aspect was exposed to EHEC strain 700728 for 30-90 min. When added to the contraluminal, but not luminal bathing medium, ACTH increased EHEC adherence within 90 min in a concentration-dependent manner (EC50 = 1.2 nM), but did not alter tissue electrical conductance. ACTH had no effect on the adherence of a pig-adapted non-O157 E. coli strain. The effect of 0.1 microM ACTH on luminal EHEC adherence was prevented in tissues pretreated contraluminally with the type 2 melanocortin receptor antagonist ACTH7-38, the neuronal conduction blocker saxitoxin, or the muscarinic cholinergic antagonist atropine. Moreover, ACTH7-38 decreased EHEC adherence in the absence of ACTH. These results suggest that ACTH acts via melanocortin receptors located on enteric nerves to enhance mucosal adherence of EHEC.
authors.affiliation: Graduate Program in Neuroscience, University of Minnesota, Minnesota 55108-6010, USA.
authors.forename: Kristin L
authors.initials: KL
authors.lastname: Schreiber
authors.forename: David R
authors.initials: DR
authors.lastname: Brown
mesh_terms: D018829:Adhesins, Bacterial / Q000187:drug effects*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D003106:Colon / Q000382:microbiology*; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology; D004553:Electric Conductivity; D019453:Escherichia coli O157 / Q000502:physiology*; D005260:Female; D007413:Intestinal Mucosa / Q000382:microbiology*; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology; D044101:Receptors, Melanocortin / Q000037:antagonists & inhibitors; D012530:Saxitoxin / Q000494:pharmacology; D013552:Swine
chemical_list: D018829:Adhesins, Bacterial; D010446:Peptide Fragments; D044101:Receptors, Melanocortin; D012530:Saxitoxin; C026034:ACTH (7-38); D001285:Atropine; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone