Center for Studies in Behavioral Neurobiology (CSBN), Department of Psychology, Concordia University, Montreal, QC H4B 1R6, Canada.
Neurobiol Learn Mem. 2013 Nov;106:221-9. doi: 10.1016/j.nlm.2013.08.018. Epub 2013 Sep 12.
Estradiol (E2) has been shown to influence learning and memory systems used by female rats to find a reward. Rats with high levels of E2 tend to use allocentric, or place, memory while rats with low levels of E2 use egocentric, or response, memory. It has been shown that systemic dopamine receptor antagonism interacts with E2 to affect which memory system is used. Here, dopamine antagonists were administered directly into either the dorsal striatum or nucleus accumbens to determine where in the brain this interaction takes place. Seventy-four young adult, female, Sprague-Dawley rats were trained and tested in a modified plus-maze. All rats were ovariectomized, received a subcutaneous low E2 implant, and were implanted with bilateral cannulae into either the dorsal striatum or the nucleus accumbens. Additionally, high E2 rats received daily injections of E2 in a sesame oil solution while low E2 rats received daily injections of vehicle. After reaching criterion levels of performance in a plus-maze task, rats were administered microinjections of either a dopamine D1 receptor (SCH 23390; 0.1 μg/ml and 0.01 μg/ml) or D2 receptor (raclopride; 2 μg/ml and 0.5 μg/ml) antagonist or a vehicle control (saline) in a counterbalanced manner. High E2 rats exhibited a trend towards a place memory bias while low E2 rats showed a response memory bias. Dorsal striatal administration of a D1, but not D2, dopamine receptor antagonist caused a switch in the memory system used by both high and low E rats. There was no significant effect of dopamine receptor antagonism in the nucleus accumbens group. Thus, E2 determined which memory system controlled behavior in a plus-maze task. Moreover, this effect was modulated by dopamine D1R antagonism in the dorsal but not ventral striatum suggesting that memory systems are, in part, mediated by E2 and dopamine in this region.
雌二醇（E2）已被证明会影响雌性大鼠寻找奖励时所使用的学习和记忆系统。E2 水平高的大鼠往往使用以地点为导向的或位置记忆，而 E2 水平低的大鼠则使用以自身为导向的或反应记忆。研究表明，系统多巴胺受体拮抗作用与 E2 相互作用会影响使用哪种记忆系统。在这里，多巴胺拮抗剂被直接注入背侧纹状体或伏隔核，以确定这种相互作用发生在大脑的哪个部位。74 只年轻成年雌性 Sprague-Dawley 大鼠在改良的加型迷宫中接受训练和测试。所有大鼠均接受卵巢切除术，植入皮下低 E2 植入物，并在背侧纹状体或伏隔核中植入双侧套管。此外，高 E2 大鼠每天接受 E2 在芝麻油溶液中的注射，而低 E2 大鼠则每天接受载体注射。在加型迷宫任务中达到标准水平的表现后，大鼠以平衡的方式接受多巴胺 D1 受体（SCH 23390；0.1μg/ml 和 0.01μg/ml）或 D2 受体（raclopride；2μg/ml 和 0.5μg/ml）拮抗剂或载体对照（生理盐水）的微量注射。高 E2 大鼠表现出位置记忆偏向的趋势，而低 E2 大鼠表现出反应记忆偏向。背侧纹状体给予 D1 但不是 D2 多巴胺受体拮抗剂会导致高 E 和低 E 大鼠使用的记忆系统发生转变。在伏隔核组中，多巴胺受体拮抗作用没有显著影响。因此，E2 决定了在加型迷宫任务中控制行为的记忆系统。此外，这种影响在背侧但不在腹侧纹状体中被多巴胺 D1R 拮抗剂调节，这表明在该区域，记忆系统部分由 E2 和多巴胺介导。
