AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 4 672-R680, Copyright © 1984 by American Physiological Society
Effects of a muramyl dipeptide on the temperature and sleep-wake cycles of the squirrel monkey
D. B. Wexler and M. C. Moore-Ede
The circadian sleep-wake and body temperature cycles of squirrel monkeys
were monitored continuously in an environment free of time cues before and
after a 50-nmol injection of a synthetic muramyl dipeptide (MDP) either 1 h
after wake-up time (subjective day) or just before sleep time (subjective
night). At both phases decreases in percent time awake (relative to saline
controls) were observed. After administration of MDP early in the
subjective day, the animals exhibited alert wakefulness only 47.4% of the
daytime, compared with a mean 86.7% of daytime after a saline control
injection. The transitional stage was significantly elevated from 6.2 to
28.7% of time after MDP. Nonrapid-eye-movement (REM) sleep was elevated in
four of five animals, but in the fifth animal, which had the least
consolidated base-line sleep-wake pattern, a small decrease in non-REM
sleep was seen. Regression analysis demonstrated a significant (P less than
0.01) relationship between the degree of sleep-wake consolidation and the
effect of MDP on non-REM sleep. Normal sleep behaviors and spontaneous
arousals were observed. MDP given at the circadian nighttime of two animals
resulted in sleep and transitional episodes occupying 84% of the subjective
night vs. 73% of time asleep after control injection. Again, these were
mostly transitional and non-REM sleep stages, and they persisted 4-5 h into
the predicted circadian daytime. REM sleep appeared to be suppressed in the
early hours after injection at either time of day.(ABSTRACT TRUNCATED AT
250 WORDS)
