[The Effect of Chronic Intermittent Hypoxia on Cognitive Function and Prefrontal Cortex Neurons in Rats].

Objective: To determine the effect of chronic intermittent hypoxia on cognitive function and prefrontal cortex neurons in rats.
Methods: 48 adult male Wistar rats were randomly divided into two groups: control group and 50 mL/L intermittent hypoxia group (50 mL/L CIH). Rats in the CIH group were placed in the low oxygen tank, simulating intermittent hypoxia environment. At 7 d, 14 d, 21 d, and 28 d, the learning and memory ability of the rats was assessed with the Morris water maze (MWM) test; the expressions of cysteinyl aspartate specific protease (caspase)-8 protein in their prefrontal cortex were determined using Western blot method; the apoptosis of neurons was detected by the TdT mediated UTP nick end labeling (TUNEL) method.
Results: Compared with the controls, the CIH rats had significantly prolonged escape latency at 14 d, 21 d, and 28 d (P<0. 05) and decreased target quadrant time (P<0. 05). The prolonged escape latency increased and target quadrant time shortened with length of exposure to hypoxia (P<0. 05). Compared with controls, the CIH rats had gradually increased caspase-8 in their frontal cortex neurons, peaked at 28 d (P<0. 05). The CIH rats showed obvious structural damage and reduced neuron density in their frontal cortex neurons. They had higher levels of nerve cell apoptosis (P<0. 05), with apoptosis index increasing with length of exposure to hypoxia (P<0. 05).
Conclusion: Severe chronic intermittent hypoxia can lead to pathological changes of frontal,cortex of rats, possibly