AJP - Regulatory, Integrative and Comparative Physiology, Vol 241, Issue 5 385-R391, Copyright © 1981 by American Physiological Society
Circadian rhythm of body temperature persists after suprachiasmatic lesions in the squirrel monkey
C. A. Fuller, R. Lydic, F. M. Sulzman, H. E. Albers, B. Tepper and M. C. Moore-Ede
Squirrel monkeys (Saimiri sciureus) demonstrate prominent circadian (approx
24 h) rhythms in many behavioral and physiological variables including
drinking and body temperature. Both of these rhythms can be entrained by a
24-h light-dark cycle (LD 12:12) but will free-run with an endogenous
period in a constantly illuminated (LL:600 lx) environment free of time
cues. After radio-frequency lesions were placed stereotaxically in the
suprachiasmatic nuclei (SCN) of five monkeys, the circadian rhythm of
drinking behavior was disrupted when the monkeys were maintained in LL.
However, the circadian rhythm in core body temperature in these animals
persisted in LL with a significant circadian spectral component following
destruction of the SCN. The SCN thus appear to be of fundamental importance
for regulating the circadian organization of drinking; however, an
oscillator located elsewhere in the squirrel monkey is capable of
generating the core body temperature rhythm.
