Rats were subjected to an ambient temperature (Ta) of 33°C for ca. 5 h during the last half of the dark phase for 5, 14 or 28 consecutive days (heat-exposed rats, HE), while control rats were kept at a constant Ta of 24°C. After the heat exposure schedule, the levels of hypothalamic temperature (Thy) as an index of body core temperature in the HE were significantly lower than those of the controls for 2–4 h in the last half of the dark phase. The low levels of Thy persisted during the specific period for 1, 3 and 6 days after the end of the 5-, 14- and 28-day heat exposure schedules, respectively. These results confirm that, in rats subjected to daily heat exposure for ca. 5 h at a fixed time per day, their Thy falls during the period when the rats were previously exposed to heat, and suggest that the duration of the specific Thy change observed after completing the heat exposure schedule depends on the length of the heat exposure schedule.
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Bolles RC, Stokes LW (1965) Rat's anticipation of diurnal and a-diurnal feeding. J Comp Physiol Psychol 60: 290–294.
Boulos Z, Rosenwasser AM, Terman M (1980) Feeding schedule and the circadian organization of behavior in the rat. Behav Brain Res 1:39–65.
Honma K, Goetz C, Aschoff J (1983) Effects of restricted daily feeding on free running circadian rhythms in rats. Physiol Behav 30:905–913.
Mori T, Nagai K, Nakagawa H (1983) Dependence of memory of meal time upon circadian biological clock in rats. Physiol Behav 30: 259–265.
Shido O, Yoneda Y, Nagasaka T (1991) Shifts in the hypothalamic temperature of rats acclimated to direct internal heat load with different schedules. J Thermal Biol 16:267–271.
Shido O, Sakurada S, Nagasaka T (1991) Effects of heat acclimation on diurnal changes in body temperature and locomotor activity in rats. J Physiol (Lond) 433:59–71.
Shido O, Yoneda Y, Nagasaka T (1989) Changes in body temperature of rats acclimated to heat with different acclimation schedule. J Appl Physiol 67:2154–2157.
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Sakurada, S., Shido, O., Sugimoto, N. et al. Changes in hypothalamic temperature of rats after daily exposure to heat at a fixed time. Pflugers Arch. 429, 291–293 (1994). https://doi.org/10.1007/BF00374326
- circadian rhythm
- body core
- heat acclimation