The mechanism of cognitive defect induced by chronic intermittent hypoxia in immature rats

Objective To investigate the mechanism of cognitive defect induced by intermittent hypoxia in immature rats.Methods Forty male Sprague-Dawley rats(3～4 week,80～100g) were randomly divided into four groups: 2-week intermittent hypoxia group(2IH),4-week intermittent hypoxia group(4IH),2-week control group(2C) and 4-week control group(4C);and 10 in each group.Intermittent hypoxia model was induced by an intermittent hypoxia cabin and the cabin was flushed with 99.99% nitrogen alternating with 99.50% oxygen.The time of one intermittent hypoxia cycle was 90s.At the end of experiments,the serum levels of 8-Iso-PGF2αwas determined by ELISA.Results The serum levels of 8-ISO-PGF2αin 2C,4C,2IH and 4IH groups were(1877.22±695.10) pg/ml,(1708.09±778.31)pg/ml,(17173.80±3082.34)pg/ml and(27098.44±7030.94)pg/ml,respectively.Compared with those in 2C,4C group,2IH and 4IH group had significantly higher levels of 8-ISO-PGF2α(P0.01,respectively).The ultrastructure of hippocampal neurons in intermittent hypoxia groups showed early apoptosis: the broken nuclear membrane,karyopyknosis and swollen mitochondria vacuoles.Conclusion Chronic intermittent hypoxia leads to oxidative stress,which may be associated with hippocampus damage and recognition degradation in weanling rats.