神经生长因子改善衰老性记忆障碍及突触机制的探讨

目的　探讨神经生长因子(NGF)改善衰老性记忆障碍的机制。方法　采用开场行为和一次性被动回避反应模型,观察海马内微量注射NGF对衰老小鼠自发活动和记忆巩固过程的影响， 同时用Ca²⁺荧光探针Fura-2/AM和AR-CM-MIC阳离子测定系统测定海马突触体游离钙水平，以³H-Leu为标记物测定海马突触体总蛋白的合成量。结果　NGF使衰老小鼠在新异环境中的自发活动和探究行为明显增多，并显著延长电击后24 h的步入潜伏期(STL); NGF显著降低衰老小鼠海马突触体内的高钙水平，并使海马突触体蛋白质的³H-Leu参入量显著增加。结论　NGF改善衰老性记忆障碍与其降低海马突触体内高钙水平，并由此促进海马突触体蛋白质的合成有关。

IMPROVING EFFECT OF NGF BY INTRAHIPPOCAMPAL INJECTION ON AGING-RELATED MEMORY IMPAIRMENT

AIM To study the improving effect of NGF (nerve growth factor) on aging-related memory impairment and its possible mechanism of action. METHODS After direct intrahippocampal injection of NGF, the spontaneous behavior and the memory retention of aging mice were observed using open field and one-trial passive avoidance test. At the same time, the free [Ca 2 ] and protein synthesis in hippocampal synaptosomes were measured in vitro by using fluorescence indicator Fura-2/AM and 3H-Leu respectively. RESULTS Compared with the control, NGF was shown to increase significantly the spontaneous behavior and explorative response in the open field, and improve remarkably the memory consolidation of old mice ( P <0 05). NGF decreased notably the intrasynaptosomal free [Ca 2 ] in hippocampus. Meanwhile, the incorporation of 3H-Leu into the synaptosomal proteins of hippocampus increased significantly. CONCLUSION NGF showed an improvement effect against the aging-related memory impairment. A decrease of intrasynaptosomal free [Ca 2 ] and an increase in protein synthesis may be involved in this effect.