低氧和运动训练对大鼠学习记忆功能的影响及其与海马突触功能可塑性之间的关系

The Interaction of Hypoxic Exposure and Exercise Training on the Learning and Memory Ability of Rats

目的:探讨低氧和运动训练对大鼠学习记忆的作用和交互作用及其与海马突触传递功能之间的关系。方法:采用交互设计的研究方案对SD大鼠进行8周14.2%的低氧暴露或/和60 min的无负重游泳训练后,通过Morris水迷宫检测大鼠的学习和记忆能力,并测定海马组织中γ-氨基丁酸(GABA)含量和N-甲基-D-天门冬氨酸受体(NMDAR)亚基NR1、NR2B的m RNA表达量。结果:1长期的低氧暴露可使大鼠的潜伏期显著增加(P<0.05),穿越平台的次数显著减少(P<0.05),运动训练能使大鼠的潜伏期显著缩短(P<0.05),穿越平台的次数显著增加(P<0.05),低氧联合运动训练对缩短大鼠潜伏期、提高大鼠穿越平台次数没有显著的交互作用(P>0.05)。2慢性低氧暴露能显著降低海马组织中NR1和NR2B m RNA的表达(P<0.05),运动训练能显著提高海马组织中NR1和NR2B的m RNA表达和降低GABA含量(P<0.05),低氧联合运动训练对海马组织中NR1、NR2B m RNA表达的提高和GABA含量的降低没有显著的交互作用(P>0.05)。结论:1长期的低氧暴露可抑制学习记忆能力,而运动训练能够增加学习记忆能力,虽然运动训练在一定程度上可以改善低氧暴露大鼠的学习记忆能力,但是并不能完全逆转低氧暴露所造成的学习能力下降。2长期的低氧暴露或运动训练可下调或上调海马NR1和NR2B m RNA表达,抑制或增强海马突触功能可塑性,这可能是影响学习记忆能力的重要机制。

Objective To investigate the action and interaction of hypoxic exposure and ＇exercise training on the learning and memory ability of rats and the role of hippocampal synaptic functional plasticity during the process. Methods＇SD rats were exposured to hypoxic condition（ 14.2% of oxygen） or/and underwent 60- min unloaded swimming for 8 weeks. Morris water maze test （MWMT） was used to measure the learning and memory ability of the rats, and the content of γ-aminobutyric acid （GABA） and the expressions subunits （NR1 and NR2B） of N-methyl-D-aspartate receptor （NMDAR） in rats＇ hippocampus were determined at the conclusion of the experiment. Results （1）Long-term hypoxic exposure increased the latency （P〈0.05） and decreased the crossing platform number of MWMT （P〈0.05） significantly,while swimming decreased latency （P〈0.05） and increased the crossing platform number （P〈0.05） of MWMT significantly. However,there was no significant interaction between hypoxic exposure and swimming in the changes in latency and crossing platform number of MWMT（P〉0.05）.（2）Long-term hypoxic exposure inhibited the mRNA expression of NR2B and NR1 significantly （P〈0.05）,and swimming improved the mRNA expression of NR2B and NR1 and decreased GABA content in hippocampus significantly（P〈 0.05）. However,there was no significant interaction between hypoxic exposure and swimming in the changes in mRNA expressions of hippocampal NR1 and NR2B and the content of GABA （P〉0.05）. Conclusion （1）Long-term hypoxic exposure inhibits and exercise training improves the ability of learning and memory. However, exercise hypoxia-induced decrease in learning and memory ability completely. training （2） The is not able to reverse the down-regulating or up- regulating the mRNA expression of NR1 and NR2B in hippocampus probably involves in the changes in ability of learning and memory during long-term hypoxic exposure or exercise training.