Long-term intermittent hypoxia in mice: protracted hypersomnolence with oxidative injury to sleep-wake brain regions

Sleep. 2004 Mar 15;27(2):194-201. doi: 10.1093/sleep/27.2.194.


Study objectives: This study was designed to test the hypothesis that long-term intermittent hypoxia (LTIH), modeling the hypoxia-reoxygenation events of sleep apnea, results in oxidative neural injury, including wake-promoting neural groups, and that this injury contributes to residual impaired maintenance of wakefulness.

Design: Sleep times and oxidative-injury parameters were compared for mice exposed to LTIH and mice exposed to sham LTIH.

Subjects: Adult male C57BL/6J mice were studied.

Interventions: Mice were exposed to LTIH or sham LTIH in the lights-on period daily for 8 weeks. Electrophysiologic sleep-wake recordings and oxidative-injury measures were performed either immediately or 2 weeks following LTIH exposures.

Measurements and results: At both intervals, total sleep time per 24 hours in LTIH-exposed mice was increased by more than 2 hours, (P<.01). Mean sleep latency was reduced in LTIH-exposed mice relative to sham LTIH mice (8.9 +/- 1.0 minutes vs 12.7 +/- 0.5 minutes, respectively, P<.01). Oxidative injury was present 2 weeks following LTIH in wake-promoting regions of the basal forebrain and brainstem: elevated isoprostane 8,12-iso-IPF2alpha-VI, 22%, P<.05; increased protein carbonylation, 50%, P<.05, increased nitration, 200%, P<.05, and induction of antioxidant enzymes glutathione reductase and methionine sulfoxide reductase A, P<.01.

Conclusions: Exposure to LTIH results in an array of significant oxidative injuries in sleep-wake regions of the brain, and these biochemical changes are associated with marked hypersomnolence and increased susceptibility to short-term sleep loss. The residual forebrain redox alterations in wake-promoting brain regions may contribute to persistent sleepiness in a prevalent disorder, obstructive sleep apnea.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Disorders of Excessive Somnolence / etiology*
  • Electrodes, Implanted
  • Hypoxia, Brain / complications*
  • Hypoxia, Brain / physiopathology*
  • Immunohistochemistry
  • Lipid Peroxidation / physiology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Oxidative Stress / physiology*
  • Prosencephalon / physiopathology
  • Sleep Disorders, Circadian Rhythm / physiopathology*