AJP - Regulatory, Integrative and Comparative Physiology, Vol 232, Issue 1 31-R37, Copyright © 1977 by American Physiological Society
Transient circadian internal desynchronization after light-dark phase shift in monkeys
M. C. Moore-Ede, D. A. Kass and J. A. Herd
In four conscious chair-acclimatized squirrel monkeys (Saimiri sciureus)
studied with lights on (600 lx) from 0800 to 2000 h daily (LD 12:12),
prominent 24-h rhythms in feeding, drinking, activity, body temperature,
and urinary potassium, sodium, and water excretion were seen. When the
monkeys were subjected to 36 h of darkness followed by 36 h of light each
variable demonstrated a circadian rhythm which was not passively dependent
on the light-dark cycle. After the 24-h light-dark cycle was abruptly
phase-delayed by 8 h, all the rhythms resynchronized with the new
light-dark cycle phase, demonstrating that light-dark cycles are an
effective zeitgeber. However, the resynchronization of the rhythms of
feeding, drinking, activity, and body temperature was 90% complete within
approximately 2 days while the 90% resynchronization of the urinary rhythms
took approximately 5 days. These results suggest that the circadian timing
system in S. sciureus may consist of several spontaneously oscillating
units which can become transiently uncoupled during pertubations of
environmental time cues.
