神经生长因子对小鼠突触体内Ca^(2+)水平的调节作用

REGULATION OF NGF ON INTRA SYNAPTOSOMAL FREE [Ca 2+ ]i IN MOUSE BRAIN

观察了多次海马内微注射ＮＧＦ对小鼠突触体内游离钙水平的影响，并在离体情况下观察ＮＧＦ对ＥＧＴＡ和ＣａＣｌ２分别造成突触体内低钙和高钙状态的调节作用。结果如下：（１）在体实验表明，一定剂量的ＮＧＦ可显著降低老年小鼠海马突触体内游离钙水平（Ｐ＜００５）；（２）离体实验表明，当突触体游离钙水平降低时，适当剂量的ＮＧＦ具有升高游离钙水平的作用；而突触体内游离钙水平升高时，则ＮＧＦ有降低游离钙水平的作用。提示ＮＧＦ对游离钙水平的双向调节作用可能是ＮＧＦ改善老年性记忆衰退的作用机制。

In the present study, the influence of direct intrahippocampal injection of NGF (nerve growth factor) on synaptosomal free [Ca 2+ ]i in 1 month old and 18 month old mice was observed.The regulation of NGF on synaptosomal free [Ca 2+ ]i in vitro was also investigated. The synaptosomal free [Ca 2+ ]i in the main brain regions (cerebral cortex, hippocampus, cerebellum, diencephalon) of these mice was measured by fluorescent probe Fura 2 of Ca 2+ indicator and an AR CM MIC cation measurement system. The results are as follows: (1) NGF showed no detectable effect on hippocampal intrasynaptosomal free [Ca 2+ ]i in 1 month old mice, but appropriate dose of NGF was shown to markedly reduce [Ca 2+ ]i in 18 month old mice. (2) Under the condition of low [Ca 2+ ]i level caused by the drug, NGF was found to increase [Ca 2+ ]i; conversely, was reduced [Ca 2+ ]i when intracellular Ca 2+ was overloaded. These results suggest that NGF has dual regulation on Ca 2+ level in brain and this might be an important mechanism for its action in improving memory lesion,in aged person.