Increased REM sleep after intra-dorsal raphe nucleus injection of flesinoxan or 8-OHDPAT: prevention with WAY 100635.
The effects of 8-OHDPAT and flesinoxan, two selective 5-HT(1A) receptor agonists, and of WAY 100635, a selective 5-HT(1A) receptor antagonist, on spontaneous sleep were studied in adult rats implanted for chronic sleep recordings. The serotonergic ligands were microinjected directly into the dorsal raphe nucleus (DRN). Direct administration of flesinoxan (25.0-50.0 ng) into the DRN induced a significant increment of REM sleep (REMS) during the second and third 2 h of recording. Microinjection of 8-OHDPAT (50.0 ng) induced similar effects on REMS during the second 2 h of recording. On the other hand, intra-DRN injection of WAY 100635 (12.5-50.0 ng) significantly reduced REMS during the second 2 h recording period. REM sleep values had also decreased significantly during the first 2 h of recording after the 50 ng dose. Pretreatment with WAY 100635 (25.0 or 50.0 ng) prevented the increase of REMS induced by flesinoxan (25.0 ng) during the second two recording hours. Our findings support the proposal that activation of somatodendritic 5-HT(1A) receptors in the DRN increases REMS, whereas their blockade induces the opposite effect.
Monti
Jaime M
JM
Department of Pharmacology and Therapeutics, Clinics Hospital, 11300, Montevideo, Uruguay.
Jantos
Héctor
H
Monti
Daniel
D
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000008:administration & dosage*; D000818:Animals; D007276:Injections, Intraventricular; D008297:Male; D008845:Microinjections; D010879:Piperazines / Q000008:administration & dosage*; D011725:Pyridines / Q000008:administration & dosage*; D011903:Raphe Nuclei / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage; D012895:Sleep, REM / Q000187:drug effects* / Q000502:physiology; D013238:Stereotaxic Techniques; D014851:Wakefulness / Q000187:drug effects* / Q000502:physiology
D010879:Piperazines; D011725:Pyridines; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C056895:flesinoxan; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin