Effects of rapid eye movement sleep deprivation on the feeding behavior in the laboratory rat with a description of the cuff pedestal technique

Abstract

The cuff pedestal technique, with which it is possible to use the test animal as its own control both before and after REMs deprivation, was described. The validity of this modified procedure for REMs deprivation was tested with reference to the electrophysiological sleep correlates using 6 adult rats deprived of REMs for 3 days. The stress effects of the cuff pedestal treatment were assessed in terms of adrenal weights in 12 rats. The duration of REMs deprivation in this experiment was 5 days. The effects of REMs deprivation on locomotor activity and food intake were studied in 8 juvenile rats exposed to REMs deprivation by lowering the cuffs for 6 days after 3 baseline days with the cuffs raised. 24 h recordings of meal pattern data were obtained from 8 adult rats during one baseline day, during the first and sixth day of REMs deprivation and during the second day after termination of REMs deprivation. The main results were as follows: The procedure of placing experimentally naive rats on small pedestals surrounded by water inhibited normal food intake for several days. Concomitant weight losses were of the same order as have been reported to occur in control rats on large pedestals. This finding suggests that both the large and small pedestals should be equipped with movable cuffs and that actual deprivation should be started by lowering the cuffs only when the animals have exceeded their original weights. The electrophysiological sleep/waking cycle of rats adapted to living on the pedestal with the cuff raised was similar to that reported in rats under ordinary laboratory conditions. Lowering of the cuffs for 3 days resulted in an almost total disappearance of REMs. A prominent rebound increase of REMs occurred after raising of the cuffs. Rats kept for fourteen days on pedestals with the cuffs raised displayed an increase of about 20% in the weights of the adrenal bodies. A quite similar adrenal hypertrophy, however, also occurs in rats living under enriched conditions. Lowering of the cuffs for the last 5 days did not induce any additional changes in the adrenal weights. These findings indicate that REMs deprivation achieved by means of the cuff pedestal does not induce any measurable physical stress. With the cuffs raised (no REMs deprivation), the rats displayed a prominent LD cycle of food intake characterized by very large meals consumed exclusively at the end of the dark period.(ABSTRACT TRUNCATED AT 400 WORDS)