Mechanisms underlying hypothalamic temperature changes during sleep in mammals

Systemic Homeostasis and Poikilostasis in Sleep

“…Of the cardiac operators influencing cardiac output, namely, heart rate and stroke volume, the first is moderately decreased in human subjects (Bristow et al, 1969;Iellamo et al, 2004;Khatri and Freis, 1967;Snyder et al, 1964;Somers et al, 1993;van de Borne et al, 1994), dogs (Schneider et al, 1997), cats (Baust and Bohnert, 1969;Mancia and Zanchetti, 1980) and mice (Schaub et al, 1998). In rabbits the decrease is Azzaroni and Parmeggiani, 1993. ) statistically either significant (Calasso and Parmeggiani, 2008) or nonsignificant (Lenzi et al, 1987).…”

“…The existence of a switch mechanism of the modality of the central integrative control of thermoregulation , respiration (Parmeggiani, 1978(Parmeggiani, , 1979 and circulation (Azzaroni and Parmeggiani, 1993) at onset and end of REM sleep was early documented by the quick phenomenal transitions of such functions.…”

“…The effect of systemic and selective brain cooling appears in the temperatures of the hindbrain and forebrain, respectively. Pontine temperature is higher than hypothalamic temperature in cats (Azzaroni and Parmeggiani, 1993;Parmeggiani et al, 1998), rabbits (Parmeggiani et al, 1998(Parmeggiani et al, , 2002 and rats (Calasso and Parmeggiani, 2004;Parmeggiani et al, 1998). Heat loss from systemic heat exchangers, affecting carotid blood temperature through the systemic venous return to the heart (systemic brain cooling), is the most important determinant of brain temperature in primates (Hayward andBaker, 1968, 1969).…”

“…The other factors to be considered are the flow and the temperature of the arterial blood supplied to the circle of Willis by different sources. The effects of a transient fall in common carotid blood flow were studied in cats and rabbits (Azzaroni and Parmeggiani, 1993;Parmeggiani et al, 2002). The fall was provoked by short (≤100s), bilateral common carotid artery occlusion during wakefulness and NREM sleep at ambient temperature (25 ± 2°C), close to thermal neutrality of these species.…”

Influence of the Temperature Signal on Sleep in Mammals

“…This feedback differentiates the relative functional weights of hypothalamic and extrahypothalamic thermoreceptors inputs in the behavioral states of wakefulness and NREM sleep. Evidently, these considerations do not apply to depressed selective hypothalamic cooling in REM sleep [6], since hypothalamic thermosensitivity is altered in this behavioral state [7][8][9][10][11].…”