CCK-8 activates hepatic vagal C-fiber afferents.
Intravenous administration of 2 micrograms/kg CCK-8 increased the single unit activity of 54% of hepatic vagal afferent fibers. Conduction velocity tests indicated that all of these units were C fibers. The increase in hepatic vagal activity produced by CCK-8 was significantly reduced by i.v. administration of 200 micrograms/kg of the CCKA receptor antagonist devazepide. Control comparisons indicated that this reduction was not an artifact of tachyphylaxis resulting from repeated administration of CCK-8. Further, the inability of pretreatment with atropine and hexamethonium to reduce the increases in hepatic vagal activity produced by CCK-8 suggests that the latter effect was not secondary to changes in gastrointestinal motor function. These outcomes demonstrate that activation of CCKA receptors by CCK-8 increases hepatic vagal afferent activity and support the view that the duodenal satiety action of CCK is mediated by the hepatic branch.
Cox
J E
JE
Department of Psychology, University of Alabama at Birmingham 35294, USA. sbsf008@uabdpo.dpo.uab.edu
Randich
A
A
D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001570:Benzodiazepinones / Q000494:pharmacology; D020109:Devazepide; D004594:Electrophysiology; D005730:Ganglionic Blockers / Q000494:pharmacology; D018738:Hexamethonium / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology; D008099:Liver / Q000294:innervation*; D008297:Male; D009412:Nerve Fibers / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D010276:Parasympatholytics / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin / Q000502:physiology; D012527:Satiation / Q000502:physiology; D012844:Sincalide / Q000494:pharmacology*; D014630:Vagus Nerve / Q000166:cytology / Q000502:physiology*
D001570:Benzodiazepinones; D005730:Ganglionic Blockers; D006727:Hormone Antagonists; D010276:Parasympatholytics; D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin; D018738:Hexamethonium; D001285:Atropine; D020109:Devazepide; D012844:Sincalide