米帮塔仙人掌多糖对小鼠慢性应激认知功能损伤的改善作用及机制探讨

Effects of Opuntia Milpa Alta Polysaccharides Treatment on Cognitive Dysfunction in Chronic Stress Mice and Its Possible Mechanisms

目的:探讨米帮塔仙人掌多糖(MAPs)对小鼠慢性应激所致认知功能损伤的改善作用及作用机制。方法:雄性昆明小鼠50只,随机分为5组(各组10只):正常对照组,慢性应激模型组,应激加MAPs低、中、高剂量组(100 mg/kg、200 mg/kg、400 mg/kg)处理,持续给药20 d。末次给药后采用新事物认知实验评价小鼠认知功能。行为学实验结束后,处死小鼠取脑,取5只用于测定海马CA1区长时程增强(LTP),另取5只采用western blot检测海马脑源性神经营养因子(BDNF)蛋白表达变化。结果:与正常对照组比较,慢性应激模型组小鼠学习记忆能力显著减退,海马CA1区LTP幅度降低,BDNF蛋白表达减少(均P<0.05);MAPs中、高剂量组小鼠认知功能明显改善,LTP幅度值增加,海马BDNF蛋白表达上调,与模型组差异有统计学意义(P<0.05)。结论:MAPs对慢性应激所致的小鼠认知功能损伤有一定的改善作用,其机制可能与上调海马BDNF蛋白的表达有关。

Objective：To investigate the effect of opuntiamilpaalta polysaccharides （MAPs） on cognitive dysfunction caused by chronic stress in mice.Methods：Fifty male adult kunming mice were randomly divided into control group,stress group and low,medium,high dose （100 mg/kg,200 mg/kg,400 mg/kg） MAPs treating groups （n=10 respectively）.Mice in the low,medium,high dose MAPs treating groups were treated with intraperitoneal injection of MAPs for 20 days.Changes of cognitive function were tested by novel-object recognition task （NOR-T）.The hippocampal CA1 region long-term potentiation （LTP） was recorded by the extracellular recordings techniques.The expression of brain derived neurotrophic factor （BDNF） in the hippocampus was detected by western blot.Results：The exploring time for the novel object,the difference index in NOR-T recognition unit,the hippocampal CA1 region LTP and the expression of BDNF protein of mice in the stress group were significantly lower than those in the control group （P〈0.05）.The exploring time for the novel object,the difference index in NOR-T recognition unit,the hippocampal CA1 region LTP and the expression of BDNF protein of mice in the medium and high dose MAPs treating groups were significantly increased compared with those in the stress group （P〈0.05）.Conclusion：MAPs can improve the cognitive dysfunction in chronic stress mice and increasing of BDNF expression in the hippocampus may be one of the mechanisms.