脑源性神经营养因子通过PI3K/Akt/mTOR信号途径对胚鼠缺氧神经元的保护作用

目的 探讨脑源性神经生长因子(brain-derived neurotrophic factor,BDNF)对缺氧(oxygen deprivation,OD)神经元的保护作用是否与激活自噬有关,其信号通路是否通过PI3K/Akt/mTOR途径。方法 1)建立胚鼠神经元OD损伤模型;CCK-8法观察不同浓度BDNF对OD神经元细胞活性的影响;2)检测OD神经元1,3,5 h自噬微管相关蛋白轻链3(LC3)的表达,情况观察BDNF对OD神经元的保护作用是否与自噬有关;3)检测p-Akt,p-mTOR,p-p70S6K以及LC3II的表达,对比BDNF与自噬激活剂雷帕霉素(mammalian target of rapamycin,Rapamycin)对Akt/mTOR/p70S6K的影响,以及自噬被3-MA抑制后,BDNF对Akt/mTOR/p70S6K的影响。结果 1)50 μg/L BDNF可对OD神经元起保护作用(P<0.05),100 μg/L BDNF效应次之;2)BDNF和/或Rapamycin在下调p-Akt/p-mTOR/p-p70S6K表达的同时可上调LC3II的表达;当3-MA抑制自噬后,BDNF对LC3II的上调作用被抑制。结论 BDNF通过PI3K/Akt/mTOR/p70S6K信号途径激活自噬,发挥对OD神经元的保护作用。

Neuronal protective effect of brain-derived neurotrophic factor mediate by autophagy through PI3K/Akt/mTOR pathway

Objective Based on growing evidence linking autophagy to ischemic preconditioning,it was hypothesized that autophagy was necessary for neuroprotection conferred by hypoxic preconditioning and further aimed to test whether brain-derived neurotrophic factor(BDNF) protects against hypoxic neuronal damage by autophagy activation and the possible signaling pathway. Methods Primary cultured cortical neurons of pregnant rats were treated with oxygen deprivation (OD) for 0.5~6 h to mimic hypoxic injury in vivo.Neuronal autophagy was measured with expression of microtubule associated protein light chain 3(LC3),and the LC3II,p-Akt,p-mTOR,and p-p70S6K protein were detected by western-blot after treated with autophagy promotor rapamycin or autophagy inhibitor 3-methyladenine(3-MA). Results 1)Compared with the control group,cells treated with 50 μg/L BDNF had the highest cell viability.2)BDNF decreased the expression of P-Akt,p-mTOR,and p-p70S6K,and increased the expression of LC3II.Similar to the roles of rapamycin to the signals,BDNF-induced up-regulation of LC3II was inhibited by 3-MA. Conclusion BDNF protects cortical neurons against oxygen deprivation damage by autophagy via PI3K/Akt/mTOR/p70S6K signaling pathway.