中文摘要：

目的 探讨不同负荷运动对老年大鼠高低难度运动学习能力的影响。方法 将72只老年SD雄性大鼠分为6组：低难度高负荷运动组、低难度中负荷运动组、低难度对照组,高难度高负荷运动组、高难度中负荷运动组和高难度对照组,每组12只。4组负荷运动组大鼠分别进行连续8周两种负荷的跑台运动。分析不同负荷运动对强条件刺激（conditioned stimulus,CS）和弱CS下的眨眼条件反应（conditioned responses,CR）的发生率、CR峰幅度以及首次达到学会标准的训练次数的影响。结果 在弱CS条件下,长期中负荷的运动可以显著地减少老年大鼠首次达到学会标准的训练次数（P〈0.05）,提高了老年大鼠的CR发生率和CR峰幅度（P〈0.05）,而长期高负荷运动则会显著地增加老年大鼠首次达到学会标准的训练次数（P〈0.05）,降低CR发生率和CR峰幅度（P〈0.05）。但是在强CS条件下,长期高负荷和中负荷运动对老年大鼠首次达到学会标准的训练次数（P〉0.05）,CR发生率和CR峰幅度均无显著影响（P〉0.05）。结论 长期中负荷运动能提高老年大鼠高难度运动学习的能力,长期高负荷运动反而损害这种能力,两种负荷运动对低难度学习能力均无明显影响。

英文摘要：

Objective To investigate the effects of different load exercises on motor learning ability of high and low skilled movements in aged rats. Methods Seventy-two aged male rats （ 16 months old） were randomly divided into 6 groups （n = 12, for each group）. Four groups were trained with two load exercises of treadmill for 8 consecutive weeks. We analyzed the effects of different load exercises on eyeblink conditioned response （CR） upon a strong or weak conditioned stimulus （CS） in aged rats according to the incidence of eyeblink CR, CR peak amplitude and training times for reaching learning criterion. Results In the presence of weak CS, the long-term high and moderate load exercises exerted different effects on the motor learning ability. The former significantly decreased the training times （P 〈 0.05 ） , and improved the incidence of CR and CR peak amplitude （P 〈 0. 05 ）, whereas the latter significantly increased the training times （ P 〈 0. 05 ）, and reduced the incidence of CR and CR peak amplitude （P 〈 0. 05）. In contrast, under the strong CS, both load exercises had no signifieant impacts on the training times, the incidence of CR and CR peak amplitude （ all P 〉 0.05 ）. Conclusion Differing from the negative effeet of long-term high load exercise, long-term moderate load exercise is benefieial for motor learning of high skilled movement in aged rats. However, both load exercises have no effects on the motor learning ability of low skilled movement.