title: Capsaicin-sensitive vagal fibres and 5-HT3-, gastrin releasing peptide- and cholecystokinin A-receptors are involved in distension-induced inhibition of gastric emptying in the rat.
abstract: The present study was undertaken to investigate how the activation of gastric mechanoreceptors by distension of the stomach in conscious gastric fistula rats influences gastric emptying; and the roles of capsaicin sensitive vagal afferent fibres and the 5-HT3, GRP and CCK-A receptors involved in mediating these responses. To activate mechanoreceptors by non-nutrient dependent pathways, methylcellulose in saline was used to distend the stomach (5 cm H2O) and the subsequent emptying of saline was examined immediately, and at 3, 5 and 10 min following distension. Prior distension delayed the subsequent emptying of saline instilled into the stomach compared with non-distended controls (2.28+/-0.09 ml/5 min; P < 0.001). Topical application of capsaicin, completely abolished the distension-induced inhibition of gastric emptying when compared with vehicle treated rats (2.82+/-0.09 vs. 2.38+/-0.04 ml/5 min; P < 0.001). Peripheral administration of a GRP antagonist (2258 U89UJ, 1 mg/kg), and a 5-HT3 antagonist (BRL4369UA, 50 microg/kg) significantly reversed (2.56+/-0.14 ml/5 min; P < 0.05 and 2.61+/-0.07 ml/5 min; P < 0.01; respectively) the delay in gastric emptying induced by distension. When the rats were treated with the CCK-A antagonist, gastric emptying of saline following distension was also significantly facilitated (2.56+/-0.07 ml/5 min; P < 0.001). In contrast, the CCK-B/gastrin receptor antagonist had no significant effect on the distension induced delay in gastric emptying (1.95+/-0.12 ml/5 min). The present results suggest that gastric distension in conscious gastric fistula rats delays gastric emptying by activating capsaicin-sensitive extrinsic afferent nerve fibres. Moreover, the results also indicate that distension-induced mechanisms involve GRP, 5-HT3 and CCK-A receptors, but not CCK-B receptors.
authors.affiliation: Department of Physiology, Marmara University, School of Medicine, Haydarpaşa, Istanbul, Turkey.
authors.forename: A
authors.initials: A
authors.lastname: Bozkurt
authors.forename: B K
authors.initials: BK
authors.lastname: Oktar
authors.forename: H
authors.initials: H
authors.lastname: Kurtel
authors.forename: I
authors.initials: I
authors.lastname: Alican
authors.forename: T
authors.initials: T
authors.lastname: Coşkun
authors.forename: B C
authors.initials: BC
authors.lastname: Yeğen
mesh_terms: D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D005746:Gastric Emptying / Q000187:drug effects / Q000502:physiology*; D017829:Granisetron / Q000494:pharmacology; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043886:Receptor, Cholecystokinin A; D018004:Receptors, Bombesin / Q000037:antagonists & inhibitors / Q000502:physiology*; D011949:Receptors, Cholecystokinin / Q000037:antagonists & inhibitors / Q000502:physiology*; D011985:Receptors, Serotonin / Q000502:physiology*; D044406:Receptors, Serotonin, 5-HT3; D012702:Serotonin Antagonists / Q000494:pharmacology; D013270:Stomach / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D014630:Vagus Nerve / Q000187:drug effects* / Q000502:physiology
chemical_list: D002211:Capsaicin; D017829:Granisetron; D009842:Oligopeptides; D043886:Receptor, Cholecystokinin A; D018004:Receptors, Bombesin; D011949:Receptors, Cholecystokinin; D011985:Receptors, Serotonin; D044406:Receptors, Serotonin, 5-HT3; D012702:Serotonin Antagonists; C077908:BW 10