螺旋藻对运动疲劳大鼠海马损伤的保护作用及机制研究

目的：研究BDNF/TrkB神经营养信号在运动疲劳大鼠海马神经元损伤中的作用与螺旋藻改善运动致脑海马损伤的作用及其可能的机制。方法：60只雄性SD大鼠随机分为：正常对照组（NC组）、正常+螺旋藻灌胃组（NS组）、运动模型组（EM组）、运动+螺旋藻灌胃组（ES组）、阳性对照组（PC组），每组12只。EM组、ES组和PC组采用3周的递增式跑台训练建立运动疲劳模型。NC组不施加任何干预，用作对照。NS组和ES组按每天300 mg/kg体重灌胃螺旋藻，PC组以同等体积的人参提取物（1.92 g/kg）灌胃，连续灌胃3周。实验末，用免疫组化和免疫印迹法检测各组大鼠海马BDNF、TrkB、p-TrkB蛋白表达水平，并用尼氏染色法观察海马CA1区形态结构的变化，同时观察大鼠体重等一般情况。结果：与NC组比较，EM组大鼠的体重降低，海马CA1区神经元细胞形态异常且排列紊乱，部分细胞固缩呈不规则变化，部分神经元消失不见，海马BDNF、TrkB和p-TrkB蛋白表达均明显升高（P<0.01）；与EM组比较，ES组大鼠的体重增加，海马神经元损伤得到明显改善，神经元数目和尼氏小体数量增加，神经元排列渐趋规则，形态较完整，ES组海马BDNF、TrkB和p-TrkB蛋白表达均明显升高（P<0.05或P< 0.01），且与PC组相比，已无明显差别（P>0.05）。结论：BDNF/TrkB神经营养信号可能参与运动致疲劳大鼠海马神经元损伤的修复过程；螺旋藻补充能改善运动疲劳大鼠海马神经元损伤，其原因可能与其上调BDNF和其受体（TrkB）及其受体磷酸化（p-TrkB）蛋白表达而发挥神经保护作用有关。

Protective effects of spirulina on hippocampal injury in exercise-fatigue mice and its mechanism

Objective: To investigate the roles of BDNF/TrkB neurotrophic signaling in hippocampal injury for fatigue rats induced by incremental load exercise and the protective effects and mechanism of spirulina supplement.Methods: Sixty SD rats were randomly divided into normal control group (NC), normal plus spirulina group(NS), exercise model group (EM), exercise plus spirulina group (ES), and positive control group (PC), 12 rats in each group.Group EM, Group ES and Group PC were applied by treadmill running with high-intensity increasing for three weeks, and Group NC had not any intervention measures.Group ES and Group NS were treated with spirulina at a dose of 300 mg/kg.bw.by intragastric administration.Group PC was gavaged at the same volume of ginseng extract of 1.92 g/kg for three weeks.The expressions of brain-derived neurotrophic factor (BDNF), tyrosine kinase recptor (TrkB), phospho-tyrosine kinase recptor (p-TrkB) were tested by Western blot and immunohistochemical method, and micromorphology changes of hippocampal CA1 were observed by light microscope at the end of the experiment.The general situations of rats such as body weights were recorded during the experiment.Results: Compared with Group NC, Group EM showed significantly decrease in body weight and hippocampal CA1 neurons of the group loosely arrayed and disarrayed and some neurons were shrinked, and even some neurons disappeared.The expressions of BDNF, TrkB and p-TrkB in group EM were increased significantly(P<0.01).Compared with Group EM, body weight of Group ES was increased significantly, and the above mentioned injuries of neurons were improved significantly:the number of neurons and nissl bodies were significantly increased and the neurons arrayed regularly and its morphology was more complete.The expressions of BDNF, TrkB and p-TrkB in the group were increased significantly(P<0.05 or P<0.01).And there was no difference between Group ES and Group PC.Conclusion: BDNF/TrkB neurotrophic signal pathway could be involved in the repair process of hippocampal nervous damage caused by incremental load exercise for fatigue rats.Spirulina supplement had a protective effect on the damaged nervous through increasing the expressions of BDNF, TrkB and p-TrkB.