游泳运动对衰老大鼠学习记忆、前额叶皮质氨基酸水平及nNOS表达的影响

摘 要］ 目的：观察游泳运动对衰老大鼠学习记忆能力及前额叶皮质(PF)氨基酸含量和神经元型一氧化氮合酶（nNOS）表达的影响，探讨游泳运动提高衰老大鼠学习记忆能力的可能机制。方法：选择20只24月龄SD衰老大鼠，随机分为衰老对照组及游泳运动组，10只5月龄大鼠作为成年对照组。成年和衰老对照组大鼠在笼内正常生活，不运动。游泳运动组大鼠采用递增负荷游泳运动，连续8周。8周后利用八臂迷宫实验测试大鼠空间学习记忆能力，检测大鼠PF中谷氨酸（Glu）及γ-氨基丁酸（GABA）水平，采用免疫组织化学结合图像半定量方法测量和分析PF中nNOS神经元的数量、面积及灰度。结果：与衰老对照组比较，游泳运动组大鼠Glu水平显著增加（P<0.05），GABA水平增加，但差异无统计学意义（P>0.05），Glu/GABA比值显著升高（P<0.05）。与衰老对照组比较，游泳运动组大鼠完成八臂迷宫时间显著缩短（P<0.05），参考记忆及总记忆错误次数均显著减少（P<0.05，P<0.01），工作记忆错误次数减少，但差异无统计学意义（P>0.05）。与衰老对照组比较，游泳运动组大鼠PF中nNOS免疫阳性细胞数量和面积均显著增加（P<0.05），灰度值显著增强（P<0.05）。结论：长期游泳运动可提高衰老大鼠的学习记忆能力，其机制可能与游泳运动增加中枢兴奋性神经递质Glu合成，有效调整Glu/GABA比值及增强大脑PF内nNOS 的表达有关。

Influence of swimming exercise in learning and memory, amino acid content and nNOS expression in prefrontal cortex of aging rats

Abstract:Objective To observe the influence of swimming exercise in learning and memory,the concents of amino acids and nNOS expression in prefrontal cortex (PF) of brain in the aging rats,and to explore the mechanism of swimming exercise to improve learning and memory of the aging rats.Methods Twenty SD aging rats (24 months) were chosen and randomly divided into aging control group(SC) and swimming exercise group(SE),and other ten SD adult rats(5 months) were used as adult control group(control).The rats in control and SC groups kept normal activities and the rats in SE group undertook an 8-week swimming exercise with progressively increasing load.Then an 8-arms radial maze was used to assess the capability of learning and memory of the rats and the contents of glutamic acid (Glu) and gamma aminobutyric acid (GABA) in PF,and the nNOS expression in PF was detected and analyzed by using ABC immunohistochemical technique and semi quantitative method.Results Compared with SC group,the Glu content in PF of the rats in SE group was significantly increased(P<0.05);the GABA content was also increased,but there was no significant difference (P>0.05);the ratio of Glu/GABA was obviously increased(P<0.05).Compared with SC group,the time of completing 8-arms radial maze of the rats in SE group was shortened (P<0.05);the reference memory error (RME) and total memory error (TE) were obviously decreased (P<0.05,P<0.01);the working memory error (WME) was decreased,but there was no significant difference(P>0.05).Compared with SC group,the amount and area of nNOS in PF of the rats in SE group were obviously increased (P<0.05),and the gray degree was enhanced (P<0.05).Conclusion Swimming exercise may enhance the learning and memory abilities of the aging rats and its mechanism might be that the swimming exercise can increase the content of Glu,effectively adjust the ratio of Glu/GABA and reinforce the expression of nNOS in PF at the same time.