Thermal and chemical stimulations of the hypothalamic heat detectors: the effects of the EEG.
In acute immobilized rats, the effect on the EEG of thermal and chemical (capsaicin microinjection) stimulation of the warm sensors in the preoptic region, mid-hypothalamic area and posterior hypothalamus were studied. Both localized heating and capsaicin resulted in a sleep-like EEG with spindles and slow waves. Stimulation of the posterior hypothalamus was the most effective and stimulation in the mid-hypothalamus was the least effective in inducing spindle activity. Since capsaicin is regarded as a specific stimulant for the hypothalamic warm sensors, the results suggest that the EEG effect, and probably the sleep-inducing effect, of heat are mediated via the central thermoreceptors, and cannot be due to a non-specific activation of the basal forebrain hypnogenic mechanisms.
D000818:Animals; D002211:Capsaicin; D004569:Electroencephalography; D006358:Hot Temperature; D007031:Hypothalamus / Q000502:physiology*; D008297:Male; D010812:Physical Stimulation; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical; D013823:Thermoreceptors / Q000502:physiology*
D002211:Capsaicin