Objective To investigate the effect and mechanism of gypenoside (GP) in improving the learning and memory ability of rats with mild cognitive impairment (MCI). Methods SD rats aged 12-15 months were randomly divided into 5 groups:sham surgery control (SSC), mild cognitive impairment model control (MCI), and low-, medium-and high-GP groups (LGP, MGP, HGP), each with 20 rats. The rat model of MCI was constructed by ligating bilateral internal carotid arteries (ICA) to induce severe stenosis, followed by persistent cerebral hypoperfusion for 2 months. Gastric lavage was performed for 2 months using GP in MCI group. The behaviors of rats, the changes of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity and the concentrations of malondialdehyde (MDA), nitric oxide synthase (NoS) and nitric oxide (No) in the cerebral cortex and hippocampus were observed. Results (1) Compared with MCI group, the latency stage in the groups LGP, MGP and HGP was shortened (P<0.01). The latency stage of HGP was close to that of SSC (P>0.05);(2) compared with MCI group, the number of crossings of the original platform was increased from LGP, MGP to HGP (P<0.01). In these three groups, the percentage of time spent in swimming in the original platform was increased successively (P<0.01). The number of crossings and the percentage of time spent in HGP were close to those of SSC (P>0.05); (3) compared with MCI, the activities of SOD and GSH-Px were increased successively from LGP, to MGP and to HGP (P<0.01);the concentrations of MDA, NOS and NO decreased in sequence (P<0.01). The activities of SOD and GSH-Px in HGP, as well as the concentrations of MDA, NOS and NO, were close to those of SSC (P>0.05). Conclusion Gypenoside improves the learning and memory ability of MCI rats by promoting the activities of SOD and GSH-Px, inhibiting the activity of NOS and reducing the contents of MDA and NO contents.%目的：探讨绞股蓝皂甙（GP）改善轻度认知功能障碍（MCI）大鼠学习记忆能力的作用及其机制。方法将12~15个月龄SD健康大鼠随机分为5组：假手术对照组（SSC组）、MCI模型对照组（MCI组）和GP低、中、高剂量组（LGP组、MGP组、HGP组），每组20只。通过结扎双侧颈内动脉（ICA）致其重度狭窄并大脑持续低灌注2个月，建立MCI大鼠模型。采用GP连续灌胃2个月作用于MCI大鼠，观察各组大鼠行为学、大脑皮层和海马超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）活性和丙二醛（MDA）、一氧化氮合酶（NOS）、一氧化氮（NO）含量的变化。结果（1）与MCI组比较，LGP组、MGP组、HGP组的潜伏期依次变短（P<0.01），其中HGP组的潜伏期接近SSC组（P>0.05）。（2）与MCI组比较，LGP组、MGP组、HGP组穿过原平台位置的次数依次增多（P<0.01）、在原平台象限游泳的时间百分比依次增高（P<0.01）；其中HGP组的次数和时间百分比接近SSC组（P>0.05）。（3）与MCI组比较，LGP组、MGP组、HGP组的SOD、GSH-Px活性依次升高（P<0.01），MDA、NOS、NO含量依次降低（P<0.01）；其中HGP组的SOD、GSH-Px活性以及MDA、NOS、NO含量接近SSC组（P>0.05）。结论绞股蓝皂甙可能通过提高脑组织SOD、GSH-Px活性、抑制NOS活性以及降低MDA、NO含量，改善MCI大鼠学习记忆能力。
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