Background Intermittent hypoxia is the main pathophysiological cause of the obstructive sleep apnea syndrome.Astragalus shows improvement of spatial leing and memory abilities under intermittent hypoxia.Our study aimed to investigate the protective effect of astragalus against intermittent hypoxia induced-hippocampal neurons impairment in rats and lay the theoretical foundation for the sleep apnea improvement in cognitive function by astragalus.Methods Male Wistar rats were divided into 4 groups:blank control group,normoxia group,intermittent hypoxia group and astragalus treated intermittent hypoxia group.After 6-week treatment,apoptosis of neurons was evaluated by terminal deoxynucleotidyl-transferase-mediated dUTP nick end-labeling (TUNEL) assay.Furthermore,the expression of HIF-1a was detected by real-time reverse transcription polymerase chain reaction (RT-PCR) at the mRNA level as well as by immunohistochemistry (IHC) and West blotting at the protein level.Results HPLC analysis indicated that astragaloside Ⅳ,astragaloside Ⅱ and astragaloside Ⅰ were the main compounds in astragals extract.Astragalus extract reduced the apoptosis of hippocampal neurons (P ＜0.05) and decreased the expression of HIF-1a at both the mRNA and protein levels in hippocampus compared with non-treated groups (P ＜0.05).Conclusion Astragalus protects against intermittent hypoxia-induced hippocampal neurons impairment in rats.