海马内钙离子水平对小鼠记忆巩固的影响

采用一次性被动回避反应模型，观察了海马（双侧）定位注射ＣａＣｌ２（２．９μｇ·只－１）和ＥＧＴＡ（１ｎｇ·只－１）对记忆巩固过程的影响。电击（０．３ｍＡ，５ｓ）后立即注射上述化合物，２４ｈ后检测，并运用Ｃａ２＋指示剂Ｆｕｒａ－２作为细胞内钙离子的荧光探针，采用精密的ＡＲ－ＣＭ－ＭＩＣ阳离子测定系统，检测了分离的单个神经细胞内游离钙及其变化。结果表明，与生理盐水对照组相比，海马内注射ＣａＣｌ２或ＥＧＴＡ都使小鼠的步入潜伏期缩短，说明记忆保持下降。以３Ｈ－亮氨酸为标记物进行的高体实验表明：ＣａＣｌ２或ＥＧＴＡ都使３Ｈ－亮氨酸参入海马突触体蛋白质的总量降低，但从ＳＤＳ－聚丙烯酰胺凝胶电泳条带来看，受这两种化合物影响的突触体蛋白质分子量范围不完全一致。提示海马内游离Ｃａ２＋水平过高或过低都能损害记忆巩固过程，其作用机理与Ｃａ２＋影响突触体蛋白质合成有关。

Effect of intrahippocampal Ca2 level on memory consolidation of mice

The memorial effects of CaCl2 and EGTA intrahippocampal injection imm ediately after the time of passive avoidance training in mice were assessed, and me intracdldar free Ca2 concentration was also measured with Fura-2 in freshly dissociated brain cells isolated from newborn(24 h)mouse pups using spex cation measuring system. Mice were trained in a one-trial passive avoidance task. The retention latency was recorded as a measure of memory.After training, the mice were immediately given bilateral intrahippocampal microinjections of CaCl2 or EGTA etc,A retention test 24 h later revealed that the retention latencies of the passive avoidance task both in CaCl2 group and in EGTA group were much shorter than that in saline group. At the same time,using 3H-Leucine as a grecursor,the treatments with CaCl2 or EGTA in the same doses showed that both CaCl2 and EGTA obviously reduced the incorporation of 3H-Leucine into hippocampal synaptosomal proteins. By means of SDS-polyacrylamide gel electrophoresis,the molecular weight ranges of synaptosomal proteins influenced by the two chemicals were not consistent,suggesting that both the lack and over-concentration of calcium ions in hippocampi could impair memory consolidation,and the mechanism may be related with the effect of Ca2 on the protein synthesis of hippocampal synaptosomes.