Serotonergic dorsal raphe neurons cease firing by disfacilitation during paradoxical sleep.
Using in vivo extracellular unit recordings combined with microdialysis infusion in the cat, we found that the cessation of discharge of presumed serotonergic dorsal raphe neurons during paradoxical sleep (PS) was completely blocked by either histamine or phenylephrine, an alpha1 adrenoceptor agonist, but not by bicuculline, a GABA receptor antagonist. In addition, application of mepyramine, a specific H1 histamine receptor antagonist, or prazosin, a specific alpha1 adrenoceptor antagonist, suppressed the spontaneous discharge of raphe neurons during both quiet waking and sleep. The present data suggest that this cessation of dorsal raphe unit activity is caused by the mechanism of disfacilitation resulting from the cessation of discharge of norepinephrine- or histamine-containing neurons during PS.
Sakai
K
K
INSERM U480, Département de Médecine Expérimentale, Université Claude Bernard, Lyon, France.
Crochet
S
S
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology*; D000322:Adrenergic Agonists / Q000494:pharmacology; D018674:Adrenergic Antagonists / Q000494:pharmacology; D000818:Animals; D002415:Cats; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D006633:Histamine Antagonists / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011903:Raphe Nuclei / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000378:metabolism*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D012895:Sleep, REM / Q000187:drug effects / Q000502:physiology*
D000322:Adrenergic Agonists; D018674:Adrenergic Antagonists; D018755:GABA Agonists; D018756:GABA Antagonists; D006633:Histamine Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin