Gene expression in rat hippocampal CA1 after the retrieval of contextual fear memory in the absence of extinction.

Adult rats (male Lister hooded) received a single unsignaled scrambled footshock (0.5 mA for 2 s) 2 min into a 3min exposure to a novel context. 48 hours later, rats were reexopsed to the condition context for 2 min (TEST). One half rats received bilateral microinfusions (1 microlitre/hemisphere) of 2 nmol/microlitre Zif268 antisense ODN (ZIFASO, 5’- GGTAGTTGTCCATGGTGG-3’in PBS, pH 7.4) or Zif268 missense ODN (ZIFMSO, 5’ -GTGTTCGGTAGGGTGTCA-3’in PBS, pH 7.4) into the dorsal hippocampus (AP -3.50, relative to bregma), 90 min before TEST. Infusions were made in awake rats via previously surgically implanted indwelling stainless steel cannula. Rats were housed in the home cages at all times outside the conditioning and TEST procedures. Rats were killed by CO2 inhalation 2 hours after TEST. CA1-enriched dorsal hippocampus was immediately dissected on ice before rapid freezing and storage at -80oC. The ZIFSO-infused group potentially represents reconsolidation-impaired rats.成年雄性李斯特帽纹大鼠（Lister hooded）在暴露于新奇环境的3分钟范式中，于第2分钟时接受单次无信号随机足底电击（0.5 mA，持续2秒）。48小时后，将大鼠再次暴露于条件化情境中2分钟，该步骤记为测试（TEST）。测试开始前90分钟，半数大鼠经背侧海马（相对于前囟（bregma）的前后坐标AP=-3.50）接受双侧微量注射：每侧半球注射1微升浓度为2纳摩尔/微升的Zif268反义寡脱氧核苷酸（antisense ODN，ZIFASO，序列为5’-GGTAGTTGTCCATGGTGG-3’，溶于pH 7.4的磷酸盐缓冲液（PBS）中）或Zif268错义寡脱氧核苷酸（missense ODN，ZIFMSO，序列为5’-GTGTTCGGTAGGGTGTCA-3’，溶于pH 7.4的PBS中）。注射操作通过术前植入的不锈钢留置套管在清醒大鼠体内完成。除条件化与测试流程外，大鼠始终饲养于标准饲养笼中。测试结束2小时后，采用二氧化碳吸入法处死大鼠。立即在冰面上分离富含CA1区的背侧海马组织，经快速冷冻后保存于-80℃环境中。接受ZIFASO注射的组别可视为记忆再巩固受损大鼠模型。