Rose S P
Department of Biology, Open University, Milton Keynes, UK.
J Physiol Paris. 1996;90(5-6):387-91. doi: 10.1016/s0928-4257(97)87926-0.
Training chicks on a one-trial passive task results in a cascade of molecular and cellular processes in two forebrain regions, culminating within 60-90 min in post-translational glycosylation of synaptic membrane proteins and expression of immediate early genes c-fos and c-jun. We have found a second window of vulnerability of memory to the protein synthesis inhibitor anisomycin, 4 h downstream of training. By 5.5 h post-training this window closes, to be replaced by a window of sensitivity to blockade of glycoprotein synthesis, presumably representing post-translational modification of the newly synthesised proteins. Amongst the pre- and post-synaptic membrane glycoproteins involved it both first and second time windows are the cell adhesion molecules, L1 (at both times) and NCAM (at the later). Molecular dissection of the external membrane domains of L1 distinguishes between a requirement for the IgG domain at the early time, the fibronectin-like domain at the later. The second time window only occurs if the animal is trained on a stimulus strong enough to be remembered for a long period. Weak memories do not persist beyond 6-8 h and the second wave of glycoprotein synthesis does not occur. Thus the second wave may represent the molecular processes required for the alterations in synaptic configuration, by way of the adhesion molecules amongst others, required for the morphological changes in neuronal connectivity hypothesised to encode memory.
在一项一次性被动任务中训练雏鸡，会在前脑的两个区域引发一系列分子和细胞过程，最终在60 - 90分钟内达到顶峰，即突触膜蛋白的翻译后糖基化以及立即早期基因c - fos和c - jun的表达。我们发现记忆对蛋白质合成抑制剂茴香霉素的第二个脆弱窗口，在训练后4小时出现。训练后5.5小时这个窗口关闭，取而代之的是对糖蛋白合成阻断敏感的窗口，这可能代表新合成蛋白质的翻译后修饰。在涉及第一个和第二个时间窗口的突触前和突触后膜糖蛋白中，有细胞粘附分子L1（在两个时间点）和NCAM（在较晚时间）。对L1外膜结构域的分子剖析表明，早期需要IgG结构域，后期需要纤连蛋白样结构域。第二个时间窗口只有在动物接受强度足以被长期记忆的刺激训练时才会出现。弱记忆不会持续超过6 - 8小时，糖蛋白合成的第二波也不会发生。因此，第二波可能代表了通过粘附分子等方式，在神经元连接的形态变化（假设用于编码记忆）中突触构型改变所需的分子过程。
