Compensatory rebound of body movements during sleep, after asphyxia in neonatal rats.
OBJECTIVE
The usefulness of body movements that occur during sleep when assessing perinatal asphyxia and predicting its long-term consequences is contradictory. This study investigated whether neonatal rats manifest these movements in compensatory rebound after asphyxia, and if these alterations play an important role in its pathogenesis.


METHODS
Eight neonatal rats (aged 6-48 h) were implanted with small EMG and EKG electrodes and sleep movements were recorded over a 30-minute control period. Recordings were continued during asphyxia caused by the enclosure of the animal in a polyvinyl sheet for 60 minutes, followed by a 30-minute recovery period.


RESULTS
Heart rate was lowered to bradycardic level during asphyxia causing behavioral agitation and increased waking time during the initial phase (30 minutes). Sleep-related movements were also significantly reduced from 12.5 +/- 0.5 (median +/- SE/2min) to 9.0 +/- 0.44 in the final half of the period (Anova, p<0.05). Movement frequency increased in the recovery period to 15.0 +/- 0.49 (Anova, p<0.05).


CONCLUSIONS
These data show that newborn rats present compensatory rebound of body movements during sleep which may help in the diagnosis of asphyxia and other problems related to sleep parameters.
Paediatrics Post-Graduate Program, Botucatu Medical School, UNESP, Brazil. olivia.suarez@yahoo.com.br
Olivia Adayr Xavier
OA
Suarez
Katsumasa
K
Hoshino
D000818:Animals; D000831:Animals, Newborn; D001237:Asphyxia / Q000150:complications / Q000503:physiopathology*; D004195:Disease Models, Animal; D004576:Electromyography; D006339:Heart Rate; D009043:Motor Activity / Q000502:physiology*; D020447:Parasomnias / Q000209:etiology / Q000503:physiopathology*; D017286:Polysomnography; D051381:Rats; D017208:Rats, Wistar; D012890:Sleep / Q000502:physiology*; D013997:Time Factors