Sh. Onen et al., Vocalization thresholds related to noxious paw pressure are decreased by paradoxical sleep deprivation and increased after sleep recovery in rat, NEUROSCI L, 291(1), 2000, pp. 25-28
The aim of this study was to assess the effect of paradoxical sleep depriva
tion (PSD) and sleep recovery on the vocalization threshold in rats submitt
ed to a mechanical noxious stimulus. Sixteen male Wistar rats were randomly
assigned in two groups: controls (n = 8), paradoxical sleep deprived rats
(n = 8). PSD was performed using the 'inverted flower pot' technique. Paw p
ressure test was used to assess the sensitivity to mechanical noxious stimu
lus (vocalization threshold). The experiment was divided into three periods
: baseline (day 1, day 2), PSD (day 3, day 4, day 5) and recovery (day 6, d
ay 7, day 8, day 9). After 48 and 72 h of PSD, the vocalization thresholds
decreased significantly in comparison to the control rats (day 4: 245 +/- 2
1 vs. 303 +/- 20 g, P = 0.05; day 5: 256 +/- 17 vs. 324 +/- 22 g, P = 0.02)
. In PSD group, relative to controls, vocalization thresholds increased sig
nificantly after 48, 72, and 96 h of recovery sleep periods (day 7: 378 +/-
24 vs. 307 +/- 8 g P = 0.01; day 8: 384 +/- 27 vs. 316 +/- 23 g, P = 0.02;
day 9: 395 +/- 24 vs. 328 +/- 15 g, P = 0.02). Vocalization thresholds on
day 6 were not significantly different in both groups (375 +/- 20 vs. 324 /- 24 g, P = 0.08). In conclusion, experimental PSD in rats induces a signi
ficant decrease in vocalization threshold to mechanical noxious stimulus, w
hich is totally reversed during the sleep recovery period. (C) 2000 Publish
ed by Elsevier Science Ireland Ltd.