Receptor subtype specific activation of the rat gastric vagal afferent fibers to serotonin.
Systemic administration (i.v.) of serotonin (5-HT) evoked a transient vagal afferent nerve discharge, bradycardia, and hypotension in the rat. The half-effective dose of 5-HT for nerve discharge was 13 micro g/kg. The time- and dose-dependent kinetics of the nerve discharge rate were similar to the change of heart rate. The afferent neuronal discharge was mimicked by a selective 5-HT3 receptor agonist, 1-phenylbiguanide hydrochloride (PBA), and inhibited by a selective 5-HT3 antagonist, granisetron. The 5-HT(3/4) agonist, cisapride partially activated the vagus nerve, but the 5-HT4 agonist, RS6733 had no effect on the vagal afferent activity. Intra-gastric perfusion of lidocaine, moreover, abolished the 5-HT-induced vagal activation. These results indicate that the 5-HT transmission signal in the gastric mucosa inputs to the brain stem via 5-HT3 receptor-mediated vagal nerve afferent.
Uneyama
Hisayuki
H
Institute of Life Sciences, Ajinomoto Co., Inc., Suzuki-Cho, Kawasaki-Ku, 210-8680, Kawasaki, Japan.
Niijima
Akira
A
Tanaka
Tatsuro
T
Torii
Kunio
K
D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D004594:Electrophysiology; D006439:Hemodynamics / Q000187:drug effects; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects*; D009475:Neurons, Afferent / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013270:Stomach / Q000187:drug effects / Q000294:innervation*; D014630:Vagus Nerve / Q000187:drug effects*
D000779:Anesthetics, Local; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin; D008012:Lidocaine