Cholecystokinin inhibits gastric motility and emptying via a capsaicin-sensitive vagal pathway in rats.
The pathway by which cholecystokinin octapeptide (CCK-8) inhibits motility of the proximal stomach and the role of this pathway in the CCK-induced delay in gastric emptying of a liquid meal has been studied in rats by selective destruction of vagal afferent C-fibers using bilateral perineural application of the sensory neurotoxin, capsaicin, 3 or 4 days prior to the experiment. The capsaicin treatment significantly attenuated the decrease in intragastric pressure in urethan-anesthetized rats in response to CCK-8 (0.1-100 pmol iv) compared with vehicle-treated controls. Removal of the celiac-superior mesenteric ganglion completely abolished the inhibitory action of CCK-8 on gastric motility in these rats. In contrast, only celiac ganglionectomy in combination with vagotomy abolished the CCK-8 effect in vehicle-treated controls. Intravenous injection of CCK-8 (300 pmol) 5 min before intragastric administration of a methylcellulose solution decreased gastric emptying by 55% in conscious control or vehicle-treated rats. Perivagal capsaicin treatment abolished the delay in gastric emptying induced by CCK-8. In addition, capsaicin treatment alone significantly increased gastric emptying. These results demonstrate that CCK-8 decreases gastric motility in the gastric corpus and delays gastric emptying by a capsaicin-sensitive vagal afferent pathway. These same afferent fibers may also play a physiological role in the gastric emptying of liquids.
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology*; D005746:Gastric Emptying / Q000187:drug effects*; D005769:Gastrointestinal Motility / Q000187:drug effects*; D011312:Pressure; D051381:Rats; D012016:Reference Values; D012844:Sincalide / Q000494:pharmacology*; D013270:Stomach / Q000294:innervation / Q000502:physiology*; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D014628:Vagotomy; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology*
D013973:Thyrotropin-Releasing Hormone; D001285:Atropine; D012844:Sincalide; D002211:Capsaicin