Neuronal Degeneration Induced Physical Stress

为了研究物理应激对大鼠大脑的影响，在成年雌性和雄性大鼠中进行了四个实验。本研究的题目如下：1.游泳训练对大鼠海马神经元的影响; 2.运动性神经元变性与海马左右半球的差异; 3.耐力游泳训练6周后大鼠学习记忆能力的变化; 4.运动性神经元变性与海马左右半球的差异。能量色散X线分析耐力游泳后大鼠海马CA 3区细胞内Ca^<2+>的变化结果表明，耐力游泳等运动应激可引起严重的神经元损伤和功能退化。游泳训练6-12周后，大鼠海马下托、海马CA 3区和齿状回出现大量暗神经元。训练12周后，海马CA 3区和海马下托细胞密度明显降低。深染神经元的轮廓与先前报道的缺血性和/或低血糖性神经变性非常相似。游泳训练12周后，大鼠大脑杏仁核、顶叶皮质1区和梨状皮质神经元明显变性。在海马，游泳训练诱发的变性神经元多见于右半球而非左半球。此外，能量色散X射线分析证实，一次2小时的游泳增加了CA 3锥体神经元细胞外Ca^2+浓度。在空间认知实验中，上述运动性神经元变性大鼠的学习能力明显低于正常大鼠。

To study the effects of physical stress on the rat brain, four experiments were took-place in adults female and male rats. The title of them were as follows ; 1.Degeneration of rat hippocampal neurons in response to swim training, 2.Difference between left and right hemispheres of rat hippocampus in relation to exercise-induced neuro-degeneration, 3.Leaming and memory abilities of rats subjected to endurance swim training for 6 weeks, and 4. Energy dispersive X-ray analysis of Intracellular Ca^<2+> in the rat hippocampal CA3 subfield after endurance swim.These experiments revealed that the exercise stress such as endurance swimming induced the serious neuronal damages and functional deterioration. In detail, Numerous dark neurons histochemically stained were found in the subiculum, CA3 subfield and dentate gyrus of rat hippoampus subjected to 2-3 h swim training for 6-12 weeks. The cell density was significantly decreased in the CA3 and subiculum after 12-week training. The profiles of darkly stained neurons were extremely similar to the ischemic and/or hypoglycemic neuro-degenerations previously reported. Also, the intensely degenerated neurons were observed in the amygdaroid, parietal cortex area 1, and piriform cortex of rat brain after 12-week swim training. In the hipocampus, the degenerated neurons induced by swim training were frequently found in the right rather than in the left hemisphere. Furthermore, Energy dispersive X-ray analysis confirmed that a bout of 2-h swimming increased the extracellular Ca^<2+> concentration of CA3 pyramidal neurons. Subjected to a spatial cognitive test, the learning ability of rats with exercise induced neuro-degeneration mentioned above was inferior to that of normal ones.