title: Subepithelial trypsin induces enteric nerve-mediated anion secretion by activating proteinase-activated receptor 1 in the mouse cecum.
abstract: Serine proteases are versatile signaling molecules and often exert this function by activating the proteinase-activated receptors (PAR(1)-PAR(4)). Our previous study on the mouse cecum has shown that the PAR(1)-activating peptide (AP) and PAR(2)-AP both induced electrogenic anion secretion. This secretion mediated by PAR(1) probably occurred by activating the receptor on the submucosal secretomotor neurons, while PAR(2)-mediated anion secretion probably occurred by activating the receptor on the epithelial cells. This present study was aimed at using trypsin to further elucidate the roles of serine proteases and PARs in regulating intestinal anion secretion. A mucosal-submucosal sheet of the mouse cecum was mounted in Ussing chambers, and the short-circuit current (I(sc)) was measured. Trypsin added to the serosal side increased I(sc) with an ED(50) value of approximately 100 nM. This I(sc) increase was suppressed by removing Cl(-) from the bathing solution. The I(sc) increase induced by 100 nM trypsin was substantially suppressed by tetrodotoxin, and partially inhibited by an NK(1) receptor antagonist, by a muscarinic Ach-receptor antagonist, and by 5-hydroxytryptamine-3 (5-HT(3)) and 5-HT(4) receptor antagonists. The I(sc) increase induced by trypsin was partially suppressed when the tissue had been pretreated with PAR(1)-AP, but not by a pretreatment with PAR(2)-AP. These results suggest that the serine protease, trypsin, induced anion secretion by activating the enteric secretomotor nerves. This response was initiated in part by activating PAR(1) on the enteric nerves. Serine proteases and PARs are likely to be responsible for the diarrhea occurring under intestinal inflammatory conditions.
authors.affiliation: Laboratory of Physiology, School of Food and Nutritional Sciences, University of Shizuoka, Yada 52-1, Surugaku, Shizuoka, 422-8526, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Ikehara
authors.forename: Hisayoshi
authors.initials: H
authors.lastname: Hayashi
authors.forename: Toshiharu
authors.initials: T
authors.lastname: Waguri
authors.forename: Izumi
authors.initials: I
authors.lastname: Kaji
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Karaki
authors.forename: Atsukazu
authors.initials: A
authors.lastname: Kuwahara
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Suzuki
mesh_terms: D000818:Animals; D000838:Anions / Q000378:metabolism*; D002432:Cecum / Q000187:drug effects / Q000378:metabolism*; D015777:Eicosanoids / Q000502:physiology; D017615:Enteric Nervous System / Q000187:drug effects / Q000502:physiology*; D007213:Indomethacin / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009637:Masoprocol / Q000494:pharmacology; D051379:Mice; D009842:Oligopeptides / Q000502:physiology; D011335:Proadifen / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D044463:Receptor, PAR-1 / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology*
chemical_list: D000838:Anions; D015777:Eicosanoids; D009842:Oligopeptides; C462999:PAR-1-activating peptide; D011480:Protease Inhibitors; D044463:Receptor, PAR-1; D012701:Serotonin; D009637:Masoprocol; D011335:Proadifen; D014357:Trypsin; D007213:Indomethacin