| The hippocampus has received considerable attention as a potential regulator of the hypothalamic-pituitary-adrencortical (HPA) axis, and chronic stress causes damage to the hippocampal neurons. The regulation activity of the hippocampus of the HPA axis is impaired by chronic stress, and homeostasis is interfered with. Exercise is a typical cause of stress and effects the hippocampus in the same way as other stressors. The influence of exercise on the microbiological characteristics of hippocampus has not been noted before. The aim of our research is to investigate the mechanics of fatigue, induced by six weeks of upgraded swimming, on the central nervous system. Changes in the microbiological characteristics of the hippocampus were observed in the following research:(1) The effect of six weeks of up-graded swimming on the physical condition of rats. After six weeks of swimming, the blood urea increased; hemoglobin, blood testosterone and body weight decreased; and kinetic ability decreased. This shows that six weeks of upgraded swimming was excessive stimulation, The rats were unable to adapt to the intensive six weeks of up-graded swimming. Therefore, rats trained by this six weeks, up-graded swimming method can be used for the following research.(2) Morphological changes of rat hippocampal neurons induced by six weeks of up-graded swimming. Morphological changes of rat hippocampal neurons were observed using light and electrical microscopes, respectively. And the changes observed were mainly the following: the neurons were loosely arrayed and some were in disarray, the neuron connections were decreased and some neurons were atrophied; "dents" were found in some nuclei; chromatin were clustered; and there were some vacuoles in the mitochondria . Over exercise can induce morphological changes of the hippocamal neurons.(3) Effect of six weeks of up-graded swimming on glutamate and ammonia content in the rat hippocampus. Six weeks of up-graded swimming caused a decrease of glutamate and an increase of ammonia in the hippocampus; and also a decreased ratio of glutamate to GABA.(4) Effect of six weeks of up-graded swimming on the BDNF in the rat hippocampus. Sixweeks of up-graded swimming caused increased expression of BDNF in damaged rat hippocampal neurons.(5) Effect of six weeks of up-graded swimming on mRNA expression of glutaminase and gluamine synthetase in the rat hippocampus. Six weeks of up-graded swimming induced increased mRNA expression of glutaminase in the rat hippocampus, and there was no change in the mRNA expression of gluamine synthetase.(6) Effect of one-time, exhaustive swimming on glutamate and ammonia content in the rat hippocampus. One-time, exhaustive swimming caused glutamate to increase in rat hippocampus, and the glutamate was neurotoxic. Therefore, exhaustive exercise can cause damage to hippocampal neurons . There was no change of ammonia content in rat hippocampus.Through the above research, logical induction led to the following: Six weeks of up-graded swimming (as also one-time exhaustive swimming) can cause morphological changes of hippocampal neurons, which are related to increased levels of glutamate and ammonia in the hippocampus. The high level of ammonia in hippocampus caused by excessive exercise can change the glutamate level and cause glutamate to decrease in the hippocampus. This, decreases the inhibiting function of the hippocampus of the HPA axiss, and induces a high level of glucocorticoid in the plasma, which destablizes the homeostasis and causes exercise fatigue.In conclusion, our study has demonstrated that excessive exercise can cause damage to hippocampal neurons and, furthermore, impair hippocampal regulation of the hypothalamic-pituitary-adrencortical (HPA) axis during stress and is considered to be one of the causal mechanisms of central fatigue.Beyond the findings of other research to date, the following are the new results of this research:1. Excessive exercise can induce morphological damage in hippocamp...
|
PDF Full Text Request