Compensatory rebound of body movements during sleep, after asphyxia in neonatal rats.

Abstract

PURPOSE: 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). CONCLUSION: 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.