Cataplexy-active neurons in the hypothalamus: implications for the role of histamine in sleep and waking behavior.
Noradrenergic, serotonergic, and histaminergic neurons are continuously active during waking, reduce discharge during NREM sleep, and cease discharge during REM sleep. Cataplexy, a symptom associated with narcolepsy, is a waking state in which muscle tone is lost, as it is in REM sleep, while environmental awareness continues, as in alert waking. In prior work, we reported that, during cataplexy, noradrenergic neurons cease discharge, and serotonergic neurons greatly reduce activity. We now report that, in contrast to these other monoaminergic "REM-off" cell groups, histamine neurons are active in cataplexy at a level similar to or greater than that in quiet waking. We hypothesize that the activity of histamine cells is linked to the maintenance of waking, in contrast to activity in noradrenergic and serotonergic neurons, which is more tightly coupled to the maintenance of muscle tone in waking and its loss in REM sleep and cataplexy.
John
Joshi
J
Neurobiology Research (151A3), Veterans Administration Greater Los Angeles Healthcare System, North Hills, CA 91343, USA.
Wu
Ming-Fung
MF
Boehmer
Lisa N
LN
Siegel
Jerome M
JM
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D002385:Cataplexy / Q000378:metabolism* / Q000503:physiopathology; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D006624:Hippocampus / Q000502:physiology; D006632:Histamine / Q000378:metabolism*; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D009129:Muscle Tonus / Q000187:drug effects / Q000502:physiology; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D012890:Sleep / Q000187:drug effects / Q000502:physiology*; D012895:Sleep, REM / Q000187:drug effects / Q000502:physiology; D013826:Theta Rhythm; D014851:Wakefulness / Q000187:drug effects / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D005680:gamma-Aminobutyric Acid; D006632:Histamine; D009638:Norepinephrine