Abstract: ObjectiveTo examine the effect of soy isoflavones on learning and memory abilities of rats after acute hypobaric hypoxia,and to explore the mechanism of the effects.MethodsThe hypoxic model was established with low pressure chamber.The high,moderate,and low dose of soy isoflavones were administered to the rats exposed to hypoxia and learning and the memory abilities of the rats were detected with Morris water maze.The contents of superoxidase dismutase(SOD) and malondialdehye(MDA) in hippocampal homogenate of the rats were determined with bilochemical assay.The protein expressions of Bcl-2 and caspase-3 in hippocapal cells were detected with immunohistochemical method.ResultsCompared to the control group,the learning and memory abilities of the model group was significantly weakened;hippocampal SOD level and Bcl-2 expression were significantly lower(76.04±16.57 vs 117.03±20.10 U/mL and 0.84±0.15 vs 1.76±0.13,P<0.01 for all),whereas the MDA levels and caspase-3 expression were significantly higher(0.87 ± 0.15 vs 0.70±0.11 nmol/mL and 0.64 ± 0.10 vs 0.64±0.09,P<0.01 for all).Compared to those of the model group,the SOD level(109.43±23.73 μ/mL) and the expression of Bcl-2(0.99±0.17) increased,and MDA content(0.75±0.11 nmol/L) and the expression of caspase-3(0.49±0.08) decreased in the rats of high dose soybean isoflavones treatment group.ConclusionSoy isoflavones enhance study ability of the rats with hypobaric hypoxia and the mechanism of the effect is related to the increase of antioxidant capacity of hippocampus and the regulation of apoptotic pathway.