Chronic upper airway obstruction induces abnormal sleep/wake dynamics in juvenile rats.
OBJECTIVE
Conventional scoring of sleep provides little information about the process of transitioning between vigilance-states. We used the state space technique to explore whether rats with chronic upper airway obstruction (UAO) have abnormal sleep/wake states, faster movements between states, or abnormal transitions between states.


METHODS
The tracheae of 22-day-old Sprague-Dawley rats were surgically narrowed to increase upper airway resistance with no evidence for frank obstructed apneas or hypopneas; 24-h electroencephalography of sleep/wake recordings of UAO and sham-control animals was analyzed using state space technique. This non-categorical approach allows quantitative and unbiased examination of vigilance-states and state transitions. Measurements were performed 2 weeks post-surgery at baseline and following administration of ritanserin (5-HT2 receptor antagonist) the next day to stimulate sleep.


RESULTS
UAO rats spent less time in deep (delta-rich) slow wave sleep (SWS) and near transition zones between states. State transitions from light SWS to wake and vice versa and microarousals were more frequent and rapid in UAO rats, indicating that obstructed animals have more regions where vigilance-states are unstable. Ritanserin consolidated sleep in both groups by decreasing the number of microarousals and trajectories between wake and light SWS, and increasing deep SWS in UAO.


CONCLUSIONS
State space technique enables visualization of vigilance-state transitions and velocities that were not evident by traditional scoring methods. This analysis provides new quantitative assessment of abnormal vigilance-state dynamics in UAO in the absence of frank obstructed apneas or hypopneas.
Sleep-Wake Disorders Unit, Soroka University Medical Center and Department of Physiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Unit of Biomedical Engineering, Department of Physics, Jerusalem College of Technology, Jerusalem, Israel.
Gideon
G
Gradwohl
Sleep-Wake Disorders Unit, Soroka University Medical Center and Department of Physiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Nilly
N
Berdugo-Boura
Shraga Segal Department of Microbiology and Immunology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Yael
Y
Segev
Sleep-Wake Disorders Unit, Soroka University Medical Center and Department of Physiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Ariel
A
Tarasiuk
D000403:Airway Resistance / Q000502:physiology; D000818:Animals; D001143:Arousal / Q000502:physiology; D004569:Electroencephalography; D051381:Rats; D017207:Rats, Sprague-Dawley; D016713:Ritanserin; D020181:Sleep Apnea, Obstructive / Q000150:complications*; D020178:Sleep Disorders, Circadian Rhythm / Q000209:etiology* / Q000473:pathology*; D018709:Statistics, Nonparametric; D014132:Trachea / Q000473:pathology / Q000601:surgery
D016713:Ritanserin