The Impact of Chronic Sleep Restriction on Neuronal Number and Volumetric Correlates of the Dorsal Respiratory Nuclei in a Rat Model

Study Objectives: Sleep restriction can result in a range of neurophysiological consequences in the brain including some brain stem nuclei. This study aimed to evaluate the effects of chronic sleep restriction (CSR) on quantitative aspects of brain stem respiratory centers using stereological methods. Methods: Male rats were randomly assigned into experimental group (CSR through a modified multiple platform apparatus), corresponding apparatus-control group (grid-floor control) and cage controls. In the grid-floor control group, animals were placed on wire-mesh grids positioned upon CSR apparatus and were then allowed to retain the opportunity to sleep. On day 21, all rats were euthanized with their brains removed for stereological assessments. The nuclei which are known to be involved in respiration rhythm including nucleus tractus solitarius (NTS), parabrachial nuclei (PB), and Kolliker-Fuse nucleus (KF) were evaluated. Results: Compared to the control groups, stereological findings in CSR rats revealed a decrease by 5.2 +/- 0.01%, 7.1 +/- 0.007%, 3.9 +/- 0.004%, and 6.3 +/- 0.002% (mean +/- standard error of the mean [SEM], p < .01 for all) in the volume of NTS, medial PB, lateral PB, and KF nuclei, respectively. Also, the total neuronal number of NTS, medial PB, lateral PB, and KF showed a significant decrease by 10.2 +/- 21.4%, 6.3 +/- 5.2%, 11.8 +/- 8.6%, and 9.3 +/- 2.5% (mean +/- SEM, p < .05 for all), respectively. Conclusions: CSR may potentially induce neuronal loss and structural changes in the dorsal respiratory nuclei.