| Hypothalamus, pituitary and adrenal are composed of the stress axis of the body. They altogether control the reaction of the external stimulation and regulate the body active process including the immunity, mood and energy use.The connection between the glands and hormones also stems from this. The exercise or taining is one of this kind of external stimulation and has a big influence on the hypothalamus-pituitary-adrenal (HPA) axis. Different studies have reported the different influence because of different intensy and durance time.These results were related to the differences of experimental aimimal age, intensy of exercise, endurance time, the patern of exercise and the state of body, including the level of the training and the time of the testing. The probably most import thing is that the body makes the cortisol in blood upper through HPA axis.HPA axis is very important for the body to mobilize the energy and essential to maintain homeostasis. Stress can occur as multiple endocrine system HPA axis and the other the hypothalamus and pituitary hormone changes. The main features of the stress response is the following HPA as the core of the activation of physiological and psychological reactions. HPA axis activation is the most important adaptive response of the stress of the body. Central control of HPA axis activation is very complex series of neuroendocrine regulation in this process, and the synthesis and release of hypothalamic CRH plays a key role in the hypothalamic paraventricular nucleus (PVN)which is the direct control of HPA axis activity site . When stimulated in, PVN neurons on the secretion of a variety of appropriate promote a lot of adrenocorticotropic hormone (ACTH) secretion of hormones, the most important thing is corticotropin-releasing hormone (CRH) and arginine vasopressin (AVP) secretion of CRH by the pituitary portal blood flow which reaches the pituitary, high affinity binding to CRH receptor (CRH-R), eventually stimulating the secretion of pituitary ACTH, which reach the adrenal gland via the blood circulation, stimulate the synthesis and secretion of adrenal glucocorticoid. There is a wholy functional regulating loop between the neuroendocrine system and immune system. Exercise stress may change the immune system's homeostasis, Whether it is the Th1/Th2 shift or not is the key to the immune homeostasis. Different forms, different load intensity and movement of different Th1/Th2 shift may have different effects on the degree and direction.Changes of hormone during exercise stress affect immune homeostasis.Exercise is also a kind of stressor. In the course of body exercise or sports training, the composition and physiological function of the body are in the event of changes, including the various components of HPA axis and its functional changes, specific to on earth what kind of change occurred in this thesis in the way of incremental exercise on the HPA axis? To what extent has it changed? This is the most important content is aimed at inthis paper.In this study, rats were used as experimental subjects, by means of the incremental exercise stress for 6 weeks, with the main line of HPA axis, with the starting point of the relevant organs in the form of the corresponding parts such as the shape of the secretion zones, hormones, and the change of molecular level, by initially interpreting and observing changes in these indices in order to obtain the influence of incremental exercise to the HPA axis of the rats. It provides the scientific and theoretical base for P.E training.The main results of this experiment are as follows:1.The influence of 6 weeks'incremental exercise on hypothalamic CRH neurons and pituitary of CRH-RCRH-positive cells are without significant changes in the beginning; for the second week group I compared with group AC has significantly decreased; at the end of the fourth week, group I set to the minimum, group3H reached the highest level; during the sixth week, there were no significant differences among the groups. It has been showed that with the increase of exercise intensity, in the context of a certain intensity, CRH cells produced varying degrees of adaptation, the body's various physiological mechanisms were to be activated by exercise to stimulate the body's response to a variety of systems, but not with the increase of exercise stress, at a certain stage, the influence upon CRH cells is even lower than the quiet level. Six weeks'incremental exercise on hypothalamic CRH-positive cells of the adaptive changes are: CRH in group AC ,during the entire experimental period , had no singnificant change; group C for the fourth week had significantly decreased; and group I, compared with group AC ,for the second and fourth weeks ,had significantly decreased and also reached the maximum at the end of the sixth week; all of which indicate that exercise load of the sixth week has largely stimulated the body so that the body had a severe reaction; for group 3H, however, there were no significant differences among the groups.In the course of the incremental exercise for six weeks, rats in the responsiveness and adaptability, in a given period, have a different degree of changes. From the point of response changes: as exercise intensity increases, CRH content for every week is not increasing, that is, as the exercise load born by the rat is concerned, when it reaches a certain intensity, the body unit will experience strong stress, but after adapting to this strength, the response to the increase in a certain range of exercise intensity is also very limited, and even in the fourth week there was no significant difference in each group. From the point of adaptive changes: there were no significant differences in group AC for weeks, indicating that mature rats own the stability of this indicator, for the other groups, there were different adaptation results showed at different stages. There was no significant difference in Group 3H for every week. In the experimental groups showed by different time, it also did not increase because of the exercise load, and experimental index in proportion to the increase of significance, indicating that rats showed different adaptation features at different times in this designed model experiment. 2.The influence of incremental exercise on rat anterior pituitary ACTH cells and adrenal ACTH-R gene expression for 6 weeksStimulation of low-intensity exercise (such as adaptive training at the beginning) also can cause severe hypothalamic response to ACTH cells, showing the very significant increase in various parts of its response to integral optical density, with the enhanced intensity ,which is also very obvious. But it also reflects such a phenomenon in the following test: with the intensity of the exercise stimulus, the reactiveness of 3H has a significant decline comparing to group I but it still exceeds group AC. The most obvious reaction that rats show to the exercise stimulus is in the end of the fourth week, but its reactiveness declines when it comes to the end of the sixth week. It can also explain that the reaction of organism comes to the maximum in a certain stimulus, once it is beyond that certain intensity, the reaction of the ACTH would not increase. That is also a kind of instinct for the protection of the organism. When it comes to the maximum reactions, the organism would do feedback to the superior organs and systems in order to be survival. It wants its superior system to reduce its positive feedback adjustment for insurance that the corresponding system won't collapse, it also ensure that the minimum of the organism is steady-state which can prevent organism from damage because of the excessive stress. From the point of adaptability of rats, the highest point of the ACTH reaction is in the fourth week in each group. What's more, its numerical volatility can illustrate the phasicness of this index and it can also show the volatility of rats to the stress, which has great similarity with reactiveness. All in all, in the course of the increasing loading movement of the six weeks, whether the reactiveness or the adaptability of the ACTH cells of rats puts up phasicness. Also, within certain stress stimulate range, its reactivness and adaptability comes to the highest point. Once beyond this range, organism would emerge defense mechanism to insure the minimum steady state in case that over stress does deadly harm to organism.3.The influence of incremental exercise on rat blood serum GC and adrenal GR gene expression for 6 weeks From the point of reactiveness of organism, as athletic intensity increases, the stimulus to organism becomes more and more fiercely and for group C of each weekend the influence is limited. That is to say, under the stimulus of different athletic intensity, organism just needs to have a day off then they can return to the absolute quiet group (AC) level with the GC produced by organism. But in the test holding on each weekend, Group I has the highest level which implies that the quantity of CG tested right after athletics achieves to the highest level. Also, the experimental result displays that compared with Group I, Group 3H has declined, but the overall level rises significantly compared to Group AC and Group C, which shows that GC haven't reduced to the quiet level. As athletic intensity increases, the change trend and responsiveness of Group I is similar, and the content of GC also has the trend to rise. But there is no conspicuous change at the weekend of the second, fourth, sixth week while Group 3H has no conspicuous change in every weekend. All of this shows that under different athletic stimulating, organism adaptability caused by different intensity is similar from the point of adaptability.From the point of reactiveness, there is no significant change between Group C and Group AC at the weekend of the beginning, the second, the fourth and the sixth weekend, which implies that the GR of Group C could restore to the quiet level after a day off under different exercise intensity of each weekend. Because the athletic intensity is low at the beginning, there is no significant change. But Group I and Group 3H are influenced by delay action of athletic effect at the second, the fourth and the sixth weekend, the genes expression level of GR is obvious beneath Group AC, which implies that with the increasing of athletic intensity, the more stimulus organism bears, the more distinct the GR declines.And the results are similar with the researchers' above . As for the adaptability, neither AC group nor C group has significant changes every weekends, also fully proves the importance of rest after motion, I group and 3H group has the lowest level of GR with the largest exercise intensity at the sixth weekend, which proves that the larger of exercise intensity, the lower level of GR in the body adrenal , and the results are similar with the study of researchers above.4.The effects of six weeks of increasing load movement on the rat's blood Th1 / Th2 balance and skeletal muscle damageThe first week, because athletic intensity is very small, experimental results are the same as the above conclusion , namely small and medium-sized load movement had no effect on rat serum IFN -γand IL - 4 content when resting after sport. failed to produced the deviation from IFN -γ/IL - 4 ratio to IL - 4 direction. May be the increasing athletic intensity make rats could not adapt to sport stimulates. cause the IFN -γ/IL - 4 ratio of I group and 3H group fell obviously, produce the deviation to IL - 4 direction, then lead to the steep descent of the cellular immune function . After the exercise on sports stimulates,the forth weeks, the rat IFN -γ/IL - 4 ratios appeared steady state, returned to level the when quiet , even the IFN -γ/IL - 4 ratio of 3H group has a very significant improvement. Until the sixth week, as athletic intensity increases, rat sport ability is getting closer to the limit, at the moment the exercise intensity is getting close to the limit.but in IFN -γ/IL - 4 ratio , there is no significant difference among I group ,3H group and AC group . The body balance of Th1 / Th2 is mainly dependent on whether to adapt to the stimulates imposed on body. The IFN -γ/IL - 4 Th1 / Th2 ratio on sixth weekend was not damaged.The first week, because the rats exercise intensity is small, there is no significant differences in the IL - 6 of each group . As the athletic intensity increases, to the second week, just the content of 3H group of is greatly lower than other groups, there is no significant difference on other groups. The forth weeks ,the athletic intensity doesn't cause 6-IL to secrete greatly, but instead a certain degree of decline, proves that this exercise load doesn't make the experiment object not adapt to, but produced a good suit. Until the sixth weeks, there is no significant change on IL - 6 of each group , also explains that skeletal muscle isn't damaged, the body could adapt to the exercise stimulates well.To summarize the experiment results above, the study shows that, with the change of exercise intensity, the CRH in the hypothalamus PVN of rats shows different adjustment features in different times , the adenohypophysis CRH - R doesn't keep pace with the changes in the CRH of the hypothalamus PVN in response and adaptability ; The ACTH cells in rat pituitary shows time phrase whether in reactivity or in the adaptability , speculates that this was one of self protection mechanism. The secretion of GC has a high degree of dependence on athletic intensity . The trend of GR gene expression is opposite to GC , shows as the athletic intensity increases, the content of GR in the body is lower, this should be one of the most homeostasis protection mechanism. The Th1 / Th2 balance shows differences in different exercise load stage , which proves the body could adapt to the sports stimulates in a certain range. There is no significant increase in IL– 6,no damage to skeletal muscle ,which is inconsistent with other researchers' results.
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