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同步观察大鼠在 7周递增负荷训练过程中血浆皮质酮、肝胞液糖皮质激素受体 (GR)和肝脏GRmRNA的动态变化 ,试图从GRmRNA水平上探讨运动应激后GR变化的机制。SD大鼠随机分为对照组 ,训练 3周组 ,训练 5周组 ,训练 7周组 ,训练 7周 +恢复 1周组。动物训练采用递增负荷的跑台训练。采用放射配体结合分析法测定肝胞液GR结合量 ;定量RT -PCR检测肝GRmRNA表达。结果发现 :(1) 7周递增负荷训练过程中 ,血浆皮质酮浓度表现为不断增加 ,至第 7周达最高 ,第 8周 (恢复周 )又降至接近对照组水平。 (2 )大鼠在 7周递增负荷训练过程中 ,肝胞液GR呈持续下降 ,至训练第 7周降至最低 ,恢复 1周后大鼠肝胞液GR有回升。 (3)在 7周递增负荷训练过程中 ,肝脏GRmRNA的变化与肝胞液GR的变化相近 ,与肝胞液GR的变化不同 ,恢复 1周后肝GRmRNA已恢复至正常水平。结果表明 ,递增运动负荷训练过程中GR结合容量的减少至少部分地发生在mRNA水平上 ,即由于GRmRNA的减少 ,造成GR分子的合成减少。但是 ,GR结合容量的恢复速度比GRmRNA慢 ,提示训练过程中 ,大鼠肝GR结合容量的减少不全是GRmRNA减少的结果 ,可能还有其他影响因素 ,比如GR结合活性的减少和 /或GR蛋白分解加速。
The dynamic changes of plasma corticosterone, hepatic cytosolic glucocorticoid receptor (GR) and hepatic GR mRNA were observed simultaneously during 7-week incremental training in order to explore the mechanism of GR changes after exercise stress. SD rats were randomly divided into control group, training 3 weeks group, training 5 weeks group, training 7 weeks group, training 7 weeks + recovery 1 week group. Animal training treadmill training with increasing load. Radioligand binding assay was used to determine the amount of GR binding in liver cells. Quantitative RT-PCR was used to detect GR mRNA expression in liver. The results showed that: (1) During the 7-week incremental load training, plasma corticosterone concentration increased continuously, reaching the highest level at the 7th week and again approaching the control level at the 8th week (recovery week). (2) In the course of 7-week incremental load training, the GR of the liver cells decreased continuously to the lowest level in the 7th week of training, and the level of GR in the liver cells increased after 1 week of recovery. (3) In the course of 7-week incremental load training, the change of GR mRNA in the liver was similar to that of the liver cytosol GR, which was different from that of the liver cytosol. After 1 week of recovery, the GR mRNA of the liver had recovered to the normal level. The results show that the decrease of GR binding capacity during atypical exercise load training occurs, at least in part, at the mRNA level, resulting in a decrease in the synthesis of GR molecules due to a decrease in GR mRNA. However, the recovery rate of GR binding capacity was slower than that of GR mRNA, suggesting that the reduction of GR binding capacity in rats during training was caused by the decrease of GR mRNA. Other possible factors such as decreased GR binding activity and / or GR protein Decomposition accelerated.