5-Hydroxytryptamine evokes three distinct responses on the rat superior cervical ganglion in vitro.
In addition to the 5-HT3-mediated fast depolarisation, 5-hydroxytryptamine (5-HT) evoked two additional responses on the rat superior cervical ganglion: a hyperpolarisation and a slow depolarisation. These responses appeared to be direct actions on 5-HT receptors since they were present in a low calcium medium containing tetrodotoxin and were not abolished by a variety of non-serotonin antagonists. The hyperpolarisation was not antagonised by 5-HT3 or 5-HT2 antagonists. The 5-HT1 ligands 5-carboxamidotryptamine (5-CT) and 8-OH-DPAT also evoked a hyperpolarisation. The hyperpolarisation was antagonised by six 5-HT1A antagonists including WB-4101 and spiroxatrine. It was therefore concluded to be mediated by a 5-HT1A receptor. The slow depolarisation was only evoked by 5-HT. The receptor involved in this response, however, could not be determined. We conclude that in addition to 5-HT3 receptors the rat superior cervical ganglion possesses 5-HT1A receptors and another uncharacterised 5-HT receptor.
Newberry
N R
NR
Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Essex, U.K.
Gilbert
M J
MJ
D000818:Animals; D005727:Ganglia, Spinal / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology
D009467:Neuromuscular Depolarizing Agents; D012702:Serotonin Antagonists; D012701:Serotonin