title: The differential effect of CB1 receptors on the discharge of afferent and efferent fibres supplying the rat jejunum.
abstract: BACKGROUND
  The cannabinoid receptor (CB(1) ) is expressed on GI sensory neurons and is suggested to play a role in food intake, inflammation and nociception. Expression of CB(1) in the nodose is influenced by nutritional status. Our aim was to determine the functional response of afferent and efferent fibres supplying the proximal jejunum to the CB(1) agonist docosatetraenylethanolamide (DEA) in fed and fasted animals.
  
  
  METHODS
  Experiments were performed on anesthetized rats, either fed ad libitum or fasted for 24 h. Blood pressure was recorded via the carotid artery and the proximal jejunum intubated to measure intraluminal pressure. A single paravascular nerve bundle was isolated and attached to an electrode for recording either afferent or efferent impulse traffic.
  
  
  RESULTS
  Docosatetraenylethanolamide (1 mg kg(-1) , i.v.) had a depressor effect on blood pressure but surprisingly had little effect on afferent nerve activity in fed animals. In fasted animals the afferent response to DEA was augmented, however, the blood pressure effect was attenuated. In contrast, DEA caused a significant and prolonged increase in efferent firing, which was diminished in fasted animals. Bilateral cervical vagotomy had no effect on the DEA-mediated efferent response, however, hexamethonium (10 mg kg(-1) ) abolished excitation and unmasked an inhibitory effect of DEA.
  
  
  CONCLUSIONS
  Docosatetraenylethanolamide has only a modest effect on intestinal afferent firing but a profound effect on efferent function, which is modulated by changes in nutritional status. The persistent response after vagotomy and block by hexamethonium suggests DEA is acting centrally, although there may be an inhibitory effect at the level of the postganglionic sympathetic neuron.
authors.affiliation: Department of Biomedical Sciences, University of Sheffield, Sheffield, UK. j.donovan@sheffield.ac.uk
authors.forename: J
authors.initials: J
authors.lastname: Donovan
authors.forename: D
authors.initials: D
authors.lastname: Grundy
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002186:Cannabinoids / Q000494:pharmacology; D007583:Jejunum / Q000294:innervation*; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D009476:Neurons, Efferent / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D043884:Receptor, Cannabinoid, CB1 / Q000819:agonists* / Q000378:metabolism*
chemical_list: D002186:Cannabinoids; D043884:Receptor, Cannabinoid, CB1