Metabolic Profiles in Soft Palate Tissue in Chronic Intermittent Hypoxia Induced Rats

Six-week-old male Sprague-Dawley rats (170±2 g) were randomly assigned to two groups, each consisting of 5 rats, and housed in polycarbonate cages. Rats were provided with standard food and water and maintained on a 12-h light/dark cycle. The CIH group rats were exposed to intermittent hypoxia using plastic cages equipped with intermittent hypoxia devices for 8 h per day, with CIH being performed during the 12-h light cycle to align with the animals' sleep cycle. CIH rats were subjected to CIH for 28 consecutive days in 8-hour daily cycles from 9:00 am to 5:00 pm. During each cycle, the internal oxygen concentration was reduced from 21% to 8.5% over 4 min and maintained at this level for 2 min. The oxygen concentration was then rapidly restored to 21% for 2 min and maintained at this level for 1 min. Animals in the control group were housed in the same chamber but were provided with a constant flow of 21% oxygen. The soft palate tissue samples collected from rats were stored at a temperature of –80 ℃.