NADPH oxidase mediates hypersomnolence and brain oxidative injury in a murine model of sleep apnea.
BACKGROUND
Persons with obstructive sleep apnea may have significant residual hypersomnolence, despite therapy. Long-term hypoxia/reoxygenation events in adult mice, simulating oxygenation patterns of moderate-severe sleep apnea, result in lasting hypersomnolence, oxidative injury, and proinflammatory responses in wake-active brain regions. We hypothesized that long-term intermittent hypoxia activates brain NADPH oxidase and that this enzyme serves as a critical source of superoxide in the oxidation injury and in hypersomnolence.


OBJECTIVE
We sought to determine whether long-term hypoxia/reoxygenation events in mice result in NADPH oxidase activation and whether NADPH oxidase is essential for the proinflammatory response and hypersomnolence.


METHODS
NADPH oxidase gene and protein responses were measured in wake-active brain regions in wild-type mice exposed to long-term hypoxia/reoxygenation. Sleep and oxidative and proinflammatory responses were measured in adult mice either devoid of NADPH oxidase activity (gp91phox-null mice) or in which NADPH oxidase activity was systemically inhibited with apocynin osmotic pumps throughout hypoxia/reoxygenation.


RESULTS
Long-term intermittent hypoxia increased NADPH oxidase gene and protein responses in wake-active brain regions. Both transgenic absence and pharmacologic inhibition of NADPH oxidase activity throughout long-term hypoxia/reoxygenation conferred resistance to not only long-term hypoxia/reoxygenation hypersomnolence but also to carbonylation, lipid peroxidation injury, and the proinflammatory response, including inducible nitric oxide synthase activity in wake-active brain regions.


CONCLUSIONS
Collectively, these findings strongly support a critical role for NADPH oxidase in the lasting hypersomnolence and oxidative and proinflammatory responses after hypoxia/reoxygenation patterns simulating severe obstructive sleep apnea oxygenation, highlighting the potential of inhibiting NADPH oxidase to prevent oxidation-mediated morbidities in obstructive sleep apnea.
Zhan
Guanxia
G
Center for Sleep and Respiratory Neurobiology, Department of Medicine, University of Pennsylvania School of Medicine, 3600 Spruce St., Philadelphia, PA 19104, USA.
Serrano
Faridis
F
Fenik
Polina
P
Hsu
Ray
R
Kong
Linghao
L
Pratico
Domenico
D
Klann
Eric
E
Veasey
Sigrid C
SC
D000818:Animals; D004195:Disease Models, Animal; D006970:Disorders of Excessive Somnolence / Q000503:physiopathology*; D015870:Gene Expression; D000860:Hypoxia / Q000503:physiopathology*; D007150:Immunohistochemistry; D008297:Male; D008562:Membrane Glycoproteins; D051379:Mice; D008810:Mice, Inbred C57BL; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000502:physiology*; D018384:Oxidative Stress; D016548:Prosencephalon / Q000378:metabolism
D008562:Membrane Glycoproteins; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases