Serotonergic regulation of noradrenergic coerulean neurons: electrophysiological evidence for the involvement of 5-HT2 receptors.
To determine the type of serotonergic receptor involved in the modulation of noradrenergic neuronal activity in the locus coeruleus, the effects of 4 systemically administered serotonergic drugs were tested on the firing rate of noradrenergic neurons in the locus coeruleus of rats under chloral hydrate anaesthesia. The serotonergic agonist, quipazine (1 mg/kg), and the selective 5-HT2 agonist, DOB (50-100 micrograms/kg), induced a pronounced decrease of the discharge frequency. This effect could be prevented or reversed by the selective 5-HT2 antagonist, ketanserin (4-8 mg/kg). Ketanserin alone and the 5-HT1 agonist, RU 24969, had no or a weak excitatory action on the neuronal activity of the locus coeruleus. We conclude that the serotonergic control of noradrenergic neurons in the locus coeruleus is mediated by post-synaptic 5-HT2 receptors because the quipazine-ketanserin effects on this unit activity persisted after depletion of serotonergic presynaptic stores.
Gorea
E
E
INSERM U. 288, Faculté de Médecine Pitié-Salpêtrière, Paris, France.
Adrien
J
J
D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine / Q000031:analogs & derivatives / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004594:Electrophysiology; D007650:Ketanserin / Q000494:pharmacology; D008125:Locus Coeruleus / Q000187:drug effects / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology*; D011814:Quipazine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000502:physiology
D011985:Receptors, Serotonin; D004290:DOM 2,5-Dimethoxy-4-Methylamphetamine; C003943:2,5-dimethoxy-4-bromoamphetamine; D011814:Quipazine; D007650:Ketanserin; D009638:Norepinephrine