神经生长因子对小鼠突触体内Ca2+水平的调节作用

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。

REGULATION OF NGF ON INTRA SYNAPTOSOMAL FREE [Ca2+]i IN MOUSE BRAIN

In the present study, the influence of direct intrahippocampal injection of NGF (nerve growth factor) on synaptosomal free Ca²⁺]i in 1-month-old and 18-month-old mice was observed.The regulation of NGF on synaptosomal free Ca²⁺]i in vitro was also investigated. The synaptosomal free Ca²⁺]i in the main brain regions (cerebral cortex, hippocampus, cerebellum, diencephalon) of these mice was measured by fluorescent probe Fura-2 of Ca²⁺ indicator and an AR-CM-MIC cation measurement system. The results are as follows: (1) NGF showed no detectable effect on hippocampal intrasynaptosomal free Ca²⁺]i in 1-month-old mice, but appropriate dose of NGF was shown to markedly reduce Ca²⁺]i in 18-month-old mice. (2) Under the condition of low Ca²⁺]i level caused by the drug, NGF was found to increase Ca²⁺]i; conversely, was reduced Ca²⁺]i when intracellular Ca²⁺ was overloaded. These results suggest that NGF has dual regulation on Ca²⁺ level in brain and this might be an important mechanism for its action in improving memory lesion,in aged person.