Effects of suprachiasmatic lesions on temperature regulation in the golden hamster.

The body temperature of individually housed golden hamsters was studied by telemetry. Elimination of circadian rhythmicity by electrolytic lesions of the suprachiasmatic nuclei of the hypothalamus (SCN) did not affect the mean level of body temperature of animals maintained at 22, 12, or 6 degrees C. The range of variation of body temperature around the mean level was also found not to differ from that of intact animals that had the circadian component filtered out by a subtractive moving-averages procedure. These results indicate that the SCN plays no role in the homeostatic control of body temperature. The role of the SCN seems to be limited to the generation of circadian rhythmicity that is superimposed on the homeostatic process of temperature regulation.