C/EBP Homologous Binding Protein (CHOP) Underlies Neural Injury in Sleep Apnea Model

Obstructive sleep apnea (OSA) is associated with cognitive impairment and neuronal injury. Long-term exposure to intermittent hypoxia (LTIH) in rodents, modeling the oxygenation patterns in sleep apnea, results in NADPH oxidase 2 (Nox2) oxidative injury to many neuronal populations. Brainstem motoneurons susceptible to LTIH injury show uncompensated endoplasmic reticulum stress responses with increased (CCAAT/enhancer binding protein homologous protein (CHOP). We hypothesized that CHOP underlies LTIH oxidative injury. In this series of studies, we first determined whether CHOP is upregulated in other brain regions susceptible to LTIH oxidative Nox2 injury and then determined whether CHOP plays an adaptive or injurious role in the LTIH response. To integrate these findings with previous studies examining LTIH neural injury, we examined the role of CHOP in Nox2, hypoxia-inducible factor-1α (HIF-1α) responses, oxidative injury and apoptosis, and neuron loss.