Mileusnic R, Lancashire C, Rose S P
Biology Department, The Open University, Milton Keynes, UK.
Learn Mem. 1999 Mar-Apr;6(2):120-7.
The functional role of NCAM gene expression in memory formation was studied in the one-trial passive avoidance task in day-old chicks by pretraining injections of one of three different 18-mer end-protected oligonucleotides corresponding to positions 190-, 207-, and 332- of the NCAM Ig1 domain. Twenty-four-hour-old chicks were trained by pecking at a bitter-tasting bead and tested for avoidance 30 min, 3, 8, or 24 hr later. Memory retention was significantly reduced only in the group of animals injected with the NCAM antisense corresponding to position 207- (AS-ODN-207), and only if given twice, both immediately after hatching and 12 hr before training. This antisense was without effect on the general behavior of the chicks, training or acquisition, and did not produce observable neurotoxic damage. Under such conditions amnesia was evident by 3 hr after training and lasted until at least 24 hr after training. The two other tested oligonucleotides were without behavioral effect. To control for nonsequence-specific effects of AS-ODN-207, brains from injected and trained animals were processed for Western blotting and probed using anti-NCAM, anti-L1, and anti-actin antibodies. NCAM antisense corresponding to position 207- significantly reduced the level of NCAM, whereas the level of L1 and actin remained unchanged. These results confirm our earlier conclusion that NCAM is necessary for longer term memory retention.
通过预先注射三种不同的18聚体末端保护寡核苷酸（分别对应于NCAM Ig1结构域的第190位、第207位和第332位），在一日龄雏鸡的单次被动回避任务中研究了NCAM基因表达在记忆形成中的功能作用。24小时龄的雏鸡通过啄食一颗苦味珠子进行训练，并在30分钟、3小时、8小时或24小时后进行回避测试。仅在注射对应于第207位的NCAM反义寡核苷酸（AS-ODN-207）的动物组中，记忆保持显著降低，且仅在孵化后立即和训练前12小时各注射一次时才出现这种情况。这种反义寡核苷酸对雏鸡的一般行为、训练或习得没有影响，也未产生可观察到的神经毒性损伤。在这种情况下，训练后3小时失忆明显，并至少持续到训练后24小时。另外两种测试的寡核苷酸没有行为学效应。为了控制AS-ODN-207的非序列特异性效应，对注射并训练的动物的大脑进行蛋白质印迹处理，并用抗NCAM、抗L1和抗肌动蛋白抗体进行检测。对应于第207位的NCAM反义寡核苷酸显著降低了NCAM的水平，而L1和肌动蛋白的水平保持不变。这些结果证实了我们早期的结论，即NCAM对长期记忆保持是必需的。
