Characterization of the in vitro effects of 5-hydroxytryptamine (5-HT) on identified neurones of the rat dorsal motor nucleus of the vagus (DMV).
1 Whole cell patch clamp techniques were used on thin brainstem slices to investigate the effects of 5-hydroxytryptamine (5-HT) on gastrointestinal-projecting dorsal motor nucleus of the vagus (DMV) neurones. Neurones were identified as projecting to the stomach (n=122) or intestine (n=84) if they contained the fluorescent tracer Dil after it had been applied to the gastric fundus, corpus or antrum/pylorus or to the duodenum or caecum. 2 A higher proportion of intestinal neurones (69%) than gastric neurones (47%) responded to 5-HT with a concentration-dependent inward current which was antagonized fully by the 5-HT2A receptor antagonist ketanserin (1 microM). 3 Stimulation of the nucleus tractus solitarius (NTS) induced inhibitory synaptic currents that were reduced in amplitude by application of the 5-HT1A receptor agonist 8-OHDPAT (1 microM) or the 5-HT1A/1B receptor agonist TFMPP (1 microM) in 61% and 52% of gastric- and intestinal-projecting neurones, respectively. 5-HT also significantly reduced the frequency but not the amplitude of spontaneous inhibitory currents. 4 These data show that 5-HT excites directly a larger proportion of intestinal projecting neurones than gastric-projecting neurones, as well as inhibiting synaptic transmission from the NTS to the DMV. These data imply that the response to DMV neurones to 5-HT may be determined and classified by their specific projections.
Browning
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KN
Neurogastroenterology Research, Henry Ford Health System, 1 Ford Place 2D, Detroit, Michigan 48202, USA.
Travagli
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RA
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D002586:Cesium / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D005260:Female; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007422:Intestines / Q000294:innervation; D007650:Ketanserin / Q000494:pharmacology; D008024:Ligands; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044302:Receptor, Serotonin, 5-HT1B; D011985:Receptors, Serotonin / Q000187:drug effects; D044263:Receptors, Serotonin, 5-HT1; D044406:Receptors, Serotonin, 5-HT3; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D017552:Solitary Nucleus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D013270:Stomach / Q000294:innervation; D009435:Synaptic Transmission / Q000187:drug effects; D000077526:Tropisetron; D014630:Vagus Nerve / Q000187:drug effects* / Q000502:physiology
D002712:Chlorides; D007211:Indoles; D008024:Ligands; D044302:Receptor, Serotonin, 5-HT1B; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D044406:Receptors, Serotonin, 5-HT3; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D002586:Cesium; C042390:alpha-methylserotonin; D012701:Serotonin; D000077526:Tropisetron; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D007650:Ketanserin; C028019:cesium chloride