Cuneiform neurons activated during cholinergically induced active sleep in the cat.
In the present study, we report that the cuneiform (Cun) nucleus, a brainstem structure that before now has not been implicated in sleep processes, exhibits a large number of neurons that express c-fos during carbachol-induced active sleep (AS-carbachol). Compared with control (awake) cats, during AS-carbachol, there was a 671% increase in the number of neurons that expressed c-fos in this structure. Within the Cun nucleus, three immunocytochemically distinct populations of neurons were observed. One group consisted of GABAergic neurons, which predominantly did not express c-fos during AS-carbachol. Two other different populations expressed c-fos during this state. One of the Fos-positive (Fos(+)) populations consisted of a distinct group of nitric oxide synthase (NOS)-NADPH-diaphorase (NADPH-d)-containing neurons; the neurotransmitter of the other Fos(+) population remains unknown. The Cun nucleus did not contain cholinergic, catecholaminergic, serotonergic, or glycinergic neurons. On the basis of neuronal activation during AS-carbachol, as indicated by c-fos expression, we suggest that the Cun nucleus is involved, in an as yet unknown manner, in the physiological expression of active sleep. The finding of a population of NOS-NADPH-d containing neurons, which were activated during AS-carbachol, suggests that nitrergic modulation of their target cell groups is likely to play a role in active sleep-related physiological processes.
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Departamento de Fisiología, Facultad de Medicina, Montevideo 11800, Uruguay.
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Morales
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D000818:Animals; D001933:Brain Stem / Q000187:drug effects / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002415:Cats; D018679:Cholinergic Agonists / Q000494:pharmacology; D009249:NADP / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000187:drug effects / Q000378:metabolism*; D012895:Sleep, REM / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018679:Cholinergic Agonists; D016760:Proto-Oncogene Proteins c-fos; D009249:NADP; D005680:gamma-Aminobutyric Acid; D002217:Carbachol; D019001:Nitric Oxide Synthase