Preoptic area warming inhibits wake-active neurons in the perifornical lateral hypothalamus.
Activation of the preoptic area (POA) warm sensitive neurons is known to promote non-REM (NREM) sleep and inhibit neuronal discharge in arousal-related brain structures. The perifornical area of the lateral hypothalamus (PF/LH) was recently recognized to be an additional important arousal promoting region. We studied the behavior of PF/LH neurons in rats during the normal sleep-wake cycle and in response to local POA warming. Most PF/LH neurons were wake-active, and exhibited low discharge throughout NREM. Seventy four percent of these wake-active neurons exhibited moderate or strong activation in REM sleep compared to NREM sleep. A substantial group (26%) exhibited very low discharge in REM as well as NREM sleep. Fifty two percent of units in the PF/LH area were responsive to POA warming; 90% of responsive neurons exhibited a significant reduction (-26.47+/-2.16% for 1 degrees C of POA warming) in their discharge rate. The inhibitory effect of POA warming on PF/LH neurons was not associated with EEG slowing. This study supports the hypothesis that sleep induction by POA warm sensitive neurons is mediated through the inhibition of multiple arousal-related structures.
Methippara
Melvi M
MM
VAMC, Research Service, Neurophysiology, 151 A3, 16111 Plummer St, North Hills, CA 91343, USA.
Alam
Md Noor
MN
Szymusiak
Ronald
R
McGinty
Dennis
D
D000818:Animals; D001831:Body Temperature / Q000502:physiology; D004569:Electroencephalography; D004576:Electromyography; D004594:Electrophysiology; D007026:Hypothalamic Area, Lateral / Q000166:cytology / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000502:physiology*; D017286:Polysomnography; D011301:Preoptic Area / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012890:Sleep / Q000502:physiology; D012895:Sleep, REM / Q000502:physiology; D013696:Temperature; D014851:Wakefulness / Q000502:physiology*