Neuronal Degeneration Induced Physical Stress

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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.