Intermittent Hypoxia Induces Cognitive Dysfunction and Hippocampal Gene Expression Changes in a Mouse Model of Obstructive Sleep Apnea

Obstructive sleep apnea syndrome (OSAS) is characterized by cycles of decreased blood oxygen saturation followed by reoxygenation due to transient apnea. Cognitive dysfunction is a complication of OSAS, but its mechanisms remain unclear. 8-week-old C57BL/6J mice were exposed to intermittent hypoxia (IH) to model OSAS, and cognitive function and hippocampal gene expression were analyzed. Three groups were maintained for 28 days: IH group (oxygen alternating between 10-21% in 2-minute cycles, 8 hours/day), sustained hypoxia group (SH) (10% oxygen, 8 hours/day), and control group (21% oxygen). Behavioral tests and RNA-seq analysis were performed. While Y-maze results showed no differences, the IH group demonstrated impaired memory and learning in passive avoidance tests compared to control and SH groups. RNA-seq revealed specific changes in learning/memory-related genes and oxidative stress response genes in the IH group. RT-qPCR showed decreased Lars2, Hmcn1, and Vstm2l expression in the IH group. Pathway analysis showed the suppression of the KEAP1-NFE2L2 antioxidant pathway in the IH group vs. SH group. Our findings demonstrate that IH may cause cognitive dysfunction through oxidative stress and suppressed antioxidant defenses. IH-specific downregulation of Lars2, Hmcn1, and Vstm2l may contribute to OSAS-related cognitive impairment.