title: GABAergic processes within the median preoptic nucleus promote NREM sleep.
abstract: GABAergic mechanisms in the preoptic region of the hypothalamus (POA) have been implicated in the generation and maintenance of NREM (quiet) sleep. We recently reported that neurons in the median peptic nucleus (MnPN) in the POA of the cat are selectively activated during NREM sleep. In the present study, we explored the hypothesis that NREM sleep is controlled by GABAergic mechanisms within the MnPN. Consequently, adult cats were utilized to determine GABA immunorreactivity within the MnPN and to examine the effects on sleep of the microinjection of a GABA(A) agonist (muscimol) and a GABA(A) antagonist (bicuculline) into this area. GABAergic neurons were present throughout the MnPN. Compared with control microinjections, after the application of muscimol, the time spent in NREM sleep (59.8±7.5 min) and REM sleep (6.9±4.7 min) decreased compared with control microinjections (103.8±5.2 and 20.2±4.3 min, respectively; P<0.005). In contrast, bicuculline microinjections increased only NREM sleep time (103.0±23.0 vs 77.7±23.7 min; P<0.05). These results demonstrate that GABAergic processes within the MnPN are involved in the generation and maintenance of sleep, especially NREM sleep.
authors.affiliation: Department of Physiology, School of Medicine, Universidad de la República, General Flores 2125, 11800 Montevideo, Uruguay.
authors.forename: Luciana
authors.initials: L
authors.lastname: Benedetto
authors.forename: Michael H
authors.initials: MH
authors.lastname: Chase
authors.forename: Pablo
authors.initials: P
authors.lastname: Torterolo
mesh_terms: D000818:Animals; D001640:Bicuculline / Q000008:administration & dosage / Q000494:pharmacology; D002415:Cats; D003627:Data Interpretation, Statistical; D004569:Electroencephalography / Q000187:drug effects; D004576:Electromyography / Q000187:drug effects; D018682:GABA Agents / Q000008:administration & dosage / Q000494:pharmacology*; D018755:GABA Agonists / Q000008:administration & dosage / Q000494:pharmacology; D018756:GABA Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D059330:GABAergic Neurons; D007150:Immunohistochemistry; D008297:Male; D008845:Microinjections; D009118:Muscimol / Q000008:administration & dosage / Q000494:pharmacology; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology*; D012890:Sleep / Q000187:drug effects / Q000502:physiology*; D012895:Sleep, REM / Q000187:drug effects; D014851:Wakefulness / Q000187:drug effects; D005680:gamma-Aminobutyric Acid / Q000378:metabolism / Q000502:physiology*
chemical_list: D018682:GABA Agents; D018755:GABA Agonists; D018756:GABA Antagonists; D009118:Muscimol; D005680:gamma-Aminobutyric Acid; D001640:Bicuculline