| More and more studies show that neuroendocrinology system plays an important role in maintenance of internal environment. As an neuro-endocrinological center, Hypothalamus-Pituitary-adrenal Axis (HPAA) has been investigated much more extensively, of which normal regulatory mechanism of such the classic axises as HPA, HPG had been studies already. Under stress, especially sports stress, changes and their mechanisms that happen to HPAA remain to be elucidated. Hence, investigations in these areas are becoming the hotspots in sports medicine. Based on the previous studies and investigations, we set up different modes of sports stresses focusing HPA axis, and investigated some important stress-related neuropeptides, i.e., -EP, AVP, and OT, etc. and measured the expression levels of AVPR mRNA in pituitary, OTR mRNA in hypothalamus and the {3 -EP precursor POMC mRNA, in order to discover any effects of different modes of sports stresses on neuro-endocrinological center, as well as relationship between neuropeptides and HPA axis.1. Modes of 9-Week Training.40 SD rats, divided randomly into 4 groups (8 rats per group): Rest-Control (Cntr), Little-Workload Training (Trnl), Middle-Workload Training (Trn2) and High-Workload Training (Tm3). Exercise for 9 week at progressive workload of different modes of Training. During 4 weeks of exercise, there is no significant change in all parameters among the 4 groups. Later, when the workload increased progressively, significant differences appeared among these groups of rats. Increase in body weight of Trin3 was slower than that in other groups, and the hemoglobulin level decreased significantly, whereas number of leukocytes increased greatly, and they ate less and behaved less actively. Thus, we concluded over-training symptoms occurred to Tm3 after 9-week high-intensity swimming exercise. While Trn2 with fixed intensity and variant time adapted gradually to exercise training after 4-5 weeks; though intensitywas increasing for the rest of time, their capacity of exercise increased gradually without apparent fatigue, indicating adaptation to exercise training.2. Effect of 9-week sport stress of different modes of exercise on expression level of POMC mRNA in hypothalamus and neuropeptide level in hypothalamus, pituitary and periphery blood.We measured the expression levels of POMC mRNA in hypothalamus and changes in -EP (derivative of POMC) in hypothalamus, pituitary and periphery blood, using RT-PCR and RIA. After 9-week exercise training, the expression levels of POMC mRNA in rat hypothalamus varied among different groups. Compared with Cntr, the POMC mRNA expression level in Trn3 was apparently up-regulated, while that of Trnl and Trn2 tended to decrease, we also found that in rat hypothalamus, compared with that in Cntr, ?-EP increased significantly in Trn3 (p<0.001) and in Tm2 (p<0.01). While in pituitary, the & -EP level tended to decrease in Trn2 (p>0.05) and Trn3 (p<0.05) compared with Cntr. In periphery blood, there is a striking increase in -EP level in Tm3 (p<0.001), whereas no significant difference occurred in other three groups. The up-regulated expression of POMC mRNA and increase in P -EP in Tm3 rat hypothalamus suggest that during long-time high-intensity exercise training, POMC system in hypothalamus is activated; while in mediate-to-small intensity progressive workload exercise, POMC mRNA expression down-regulates, indicative of a kind of adaptation. In pituitary, POMC derivative of $ -EP decreases, while in periphery blood, ACTH increases, our interpretation is that over-training makes POMC prone preferentially to split into ACTH.3. Effect of 9-week sport stresses on GR mRNA expression and GR affinity as well as some hormones in HPA axis in rat hippocampus and hypothalamus.Using RT-PCR, RIA and radio-labeled ligand binding assay, we found that, in hypothalamus of Tm3 rat, GR mRNA expression was down-regulated, and those of Trnl and Trn2 had the same tendency. In hippocampus, GR mRNA expression in Trn3 rat had the same change...
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