[Heat sensitivity of the medial preoptic area of the hypothalamus during seasonal adaptation and acclimation to high environmental temperature].

The activation threshold of the vascular heat dissipation response to local heating of the preoptic hypothalamus was studied with respect to year's seasons and in heat acclimation. The seasonal adaptation to high ambient temperature was followed by a shift of the thermal neutrality zone and a related change of the absolute temperature threshold of the heat dissipation response. The latter was triggered throughout the year by a raise of temperature of the medial preoptic area from the initial level by 0.92 +/- 0.07 degrees C on the average. This finding suggests that the relative heat sensitivity of the anterior hypothalamus does not change in adaptation to high ambient temperature.