Changes in hypothalamic and body temperatures during 24 hours in rats.

The available information on simultaneous assessment of body and hypothalamic temperatures in rats are lacking. In the present study these temperatures were recorded for 24 h, on three alternate days, in rats maintained at an ambient temperature of 26 +/- 1 degrees C. Hypothalamic temperature was significantly higher than body temperature during the night. In nocturnal rats the magnitude of circadian variation in hypothalamic temperature was higher than body temperature. Though maintained at different levels, both the temperatures showed closely associated diurnal changes throughout the 24 h period.