title: Activation of proteinase-activated receptor-1 inhibits neurally evoked chloride secretion in the mouse colon in vitro.
abstract: The proteinase-activated thrombin receptor-1 (PAR-1) belongs to a unique family of G protein-coupled receptors activated by proteolytic cleavage. We studied the effect of PAR-1 activation in the regulation of ion transport in mouse colon in vitro. Expression of PAR-1 in mouse colon was assessed by RT-PCR and immunohistochemistry. To study the role of PAR-1 activation in chloride secretion, mouse colon was mounted in Ussing chambers. Changes in short-circuit current (Isc) were measured in tissues exposed to either thrombin, saline, the PAR-1-activating peptide TFLLR-NH2, or the inactive reverse peptide RLLFT-NH2, before electrical field stimulation (EFS). Experiments were repeated in the presence of either a PAR-1 antagonist or in PAR-1-deficient mice to assess receptor specificity. In addition, studies were conducted in the presence of chloride-free buffer or the muscarinic antagonist atropine to assess chloride dependency and the role of cholinergic neurons in the PAR-1-induced effect. PAR-1 mRNA was expressed in full-thickness specimens and mucosal scrapings of mouse colon. PAR-1 immunoreactivity was found on epithelial cells and on neurons in submucosal ganglia where it was colocalized with both VIP and neuropeptide Y. After PAR-1 activation by thrombin or TFLLR-NH2, secretory responses to EFS but not those to forskolin or carbachol were significantly reduced. The reduction in the response to EFS was not observed in the presence of the PAR-1 antagonist, in PAR-1-deficient mice, when chloride was excluded from the bathing medium, or when atropine was present. PAR-1 is expressed in submucosal ganglia in the mouse colon and its activation leads to a decrease in neurally evoked epithelial chloride secretion.
authors.affiliation: Mucosal Inflammation Research Group, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Buresi
authors.forename: Nathalie
authors.initials: N
authors.lastname: Vergnolle
authors.forename: Keith A
authors.initials: KA
authors.lastname: Sharkey
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Keenan
authors.forename: Patricia
authors.initials: P
authors.lastname: Andrade-Gordon
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cirino
authors.forename: Donatella
authors.initials: D
authors.lastname: Cirillo
authors.forename: Morley D
authors.initials: MD
authors.lastname: Hollenberg
authors.forename: Wallace K
authors.initials: WK
authors.lastname: MacNaughton
mesh_terms: D000818:Animals; D002712:Chlorides / Q000378:metabolism*; D003106:Colon / Q000737:chemistry / Q000294:innervation / Q000502:physiology*; D015870:Gene Expression; D066298:In Vitro Techniques; D007413:Intestinal Mucosa / Q000737:chemistry / Q000378:metabolism*; D017136:Ion Transport; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009478:Neuropeptide Y / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D044463:Receptor, PAR-1 / Q000032:analysis / Q000502:physiology*; D015398:Signal Transduction; D014660:Vasoactive Intestinal Peptide / Q000032:analysis
chemical_list: D002712:Chlorides; D009478:Neuropeptide Y; D012333:RNA, Messenger; D044463:Receptor, PAR-1; D014660:Vasoactive Intestinal Peptide