Effects of intermittent hypoxia on expression of phosphorylated JNK in rats

Objective To investigate the effects of intermittent hypoxia on phosphorylated JNK expression and learning and memory functions in rats.Methods One hundred and twenty male Sprague-Dawley rats were randomly divided into three groups:control group,mild intermittent hypoxia group,and severe intermittent hypoxia group.The rats in control group were exposed to ambient air and the rats in two intermittent hypoxia groups were exposed to different intermittent hypoxia conditions(100 ml/L and 50 ml/L,8-hour-intermittent hypoxia a day with the exposure durations of 2,4,6,and 8 weeks,respectively).The learning and memory functions were measured with water maze test;the morphological changes were observed with light microscopy;the expression of phosphorylated JNK protein was detected with immunohistochemistry and western-blotting.Results Compared with the control group,the hippocampal brain structure was damaged in intermittent hypoxia rats with the increase of hypoxia time,and the phosphorylated JNK expressions increased obviously.Water maze test showed that escaping latency was prolonged and the number of crossing site was reduced.The changes were more significant in severe intermittent hypoxia group(P＜0.05).Six and eight weeks after the hypoxia exposure,the phosphorylated JNK expressions in mild intermittent hypoxia group and severe intermittent hypoxia group were 5.84 ±1.17,3.58±1.0 and 7.86±1.56,9.78±3.41,respectively,with significant increase in severe intermittent hypoxia group(P＜0.05).Conclusion Intermittent hypoxia can cause learning and memory impairments and the effects might be related to the JNK activation induced by different duration and severity of intermittent hypoxia.