不同强度的游泳训练对脑缺血再灌注大鼠蛋白激酶A表达的影响

Effects of different intensities of swimming training on the expressions of protein kinase A after cerebral ischemia-reperfusion in rats

目的探讨强化游泳训练对脑缺血再灌注大鼠神经功能及蛋白激酶A（PKA）表达的影响。 方法采用线栓法建立左侧大脑中动脉阻塞（MCAO）2 h再灌注动物模型。120只造模成功的雄性SD大鼠按随机数字表法分为训练1组、训练2组、训练3组和MCAO对照组，每组30只。训练1组大鼠每日游泳5 min，训练2组大鼠每日游泳10 min，训练3组大鼠每日游泳20 min；MCAO对照组大鼠不给予任何训练。另选30只大鼠为假手术组，不阻塞大脑中动脉血流，不给予任何训练。以上5组大鼠又分别随机分为术后3、7和14 d三个时间点亚组，每个时间点10只大鼠。分别于术后3、7和14 d三个时间点，采用Menzies神经行为评分和前肢放置试验评价各亚组大鼠神经功能缺损情况，采用免疫组织化学方法测定各亚组大鼠脑缺血再灌注后脑内PKA阳性细胞的表达率，采用RT-PCR的方法测定各亚组大鼠脑缺血侧大脑皮质PKA的mRNA表达量，并进行统计学分析比较。 结果假手术组神经功能正常。MCAO对照组各时间点的神经功能评分与假手术组同时间点比较，组间差异均有统计学意义（P〈0.05）；各训练组分别在训练3、7和14 d后的神经功能改善情况优于同时间点MCAO对照组；训练3组训练14 d后受损神经功能改善最明显（P〈0.05），其训练3、7和14 d后的Menzies评分分别为（1.40±0.55）、（1.00±0.71）和（0.80±0.45）分，前肢放置试验评分分别为（5.20±0.84）、（3.80±1.30）和（2.40±1.14）分。训练1、2和3组各时间点的PKA阳性细胞表达率及其mRNA表达量高于同时间点MCAO对照组；且训练3组训练14 d后的PKA阳性细胞表达率及其mRNA表达量增加较其它各训练组更为明显（P〈0.05），其训练3、7和14 d后的PKA阳性细胞表达率分别为（32.84±1.66）%、（35.05±1.33）%和（45.92±2.03）%，PKA mRNA表达量分别为（32.18±0.86）%、（37.44±1.27）%和（42.77±0.81）%。 结论强化游泳训练可以增加脑缺血再灌注大鼠PKA阳性细胞表达率及其mRNA表达量，改善受损神经功能，促进感觉和运动功能恢复。

Objective To observe the effects of intensive-swimming training at different intensities on the neurological function and the expressions of protein kinase A after cerebral isehemia-reperfusion in rats, and to explore the possible neuroproteetion mechanism of intensive-swimming training after cerebral ischemia-reperfusion in rats. Methods The animal model of cerebral ischemia-reperfusion was established in rats by using the intraluminal thread method to cause left middle cerebral artery occlusion （MCAO） for 2 h and then reperfusion. A total of 120 male model Sprague-Dawley rats were randomly divided into training group 1 （ swimming for 5 min once a day） , training group 2 （ swimming for 10 min once a day） , training group 3 （ swimming for 20 rain once a day） and control group （no training） , with 30 rats in each group. Another 30 rats who were assigned to the sham-operation group were subject to no MCAO and no training. At the 3rd, 7th and 14th day post operation, 10 rats randomly selected from each group were examined for their neurological function by Menzies neurobehav±ioral test and forelimb placing test. Expressions of protein kinase A were detected by immunohistochemistry method. Expressions of PKA-mRNA were detected by using RT-PCR. Results The neurological function in sham-operation group was normal. The differences between sham-operation group and control group with regard to Menzies test and forelimb placing test scores were statistically significant at all the time points （ P 〈 0.05 ）. The improvement of neurological function in all training groups, were significantly better than those in controls at the 3 rd, 7th and 14th d after swimming training, especially in training group 3 on the 14th day post-operation （P 〈 0.05）. At 3rd, 7th, and 14th days post-operation, the Menzies scores were（1.40 ±0.55）,（1.00±0.71） and （0.80±0.45） , respectively, and the forelimb placing scores were（5.20 ±0. 84） ,（3. 80 ± 1. 30） and （2.40 ± 1. 14 ） , respectively, in the training group 3. The number of positive cells and the expressions of protein kinase A mRNA were significantly higher in all training groups than those in the controls at the 3rd, 7th and 14th days after swimming training, and the increase of positive cells and mRNA of PKA in the training group 3 was significantly more obvious at 14th day compared with other training groups（P 〈 0.05 ）. Conclusions Exercise training can increase the expression of positive cells and mRNA of PKA in rats after cerebral ischemiareperfusion, hence, it improved the injured neurological function and promote the recover of sensory and motor function, and the more intensive the training, the better the effects.