Holahan Matthew R, Nichol Jeremy, Madularu Dan
Department of Psychology, Institute of Neuroscience Carleton University, 1125 Colonel By Drive, B550 Loeb Building, Ottawa, Ont. K1S5B6, Canada.
Neurobiol Learn Mem. 2008 Sep;90(2):434-42. doi: 10.1016/j.nlm.2008.05.001. Epub 2008 Jun 24.
The purpose of the present study was to examine the role of the dorsal striatum, and more specifically, the patch region of the dorsal striatum, in mediating spatial learning and memory. To this end, male, Long Evans rats were bilaterally implanted with cannula aimed at the dorsal striatum. Rats were injected with different doses (0, 0.05, 0.5 or 5 microg/0.5 microl) of [3H]-[D-Ala2,MePhe4,Gly-ol5]-enkephalin (DAMGO) into the dorsal striatum daily (Exp. 1) before training on a hidden platform version of the water maze task or during a reversal water maze spatial task (Exp. 2). In both experiments, probe retention tests were given drug free. Results from Exp. 1 showed that intra-striatal injection of the low DAMGO dose (0.05) resulted in enhanced spatial acquisition while the high dose (5.0) produced impairments compared to controls. During the probe test, the low dose group showed better retention of the platform location than controls as well as an enhanced ability to alter their search strategy. In Exp. 2, pretraining alleviated the high dose impairment found in Exp. 1 suggesting a motoric impairment in this group. The low dose group continued to show an enhanced ability to alter their search strategy during the probe test compared to all other groups. The data suggest that the low dose of DAMGO, when injected into the dorsal striatum, eliminates competition with the hippocampus thereby leading to enhanced spatial processing. Alternatively, inhibition of patch-striatal neurons may attenuate a memory decay process. Both alternatives are discussed.
本研究的目的是考察背侧纹状体，更具体地说是背侧纹状体的斑块区域，在介导空间学习和记忆中的作用。为此，对雄性Long Evans大鼠双侧植入针对背侧纹状体的套管。在水迷宫任务的隐藏平台版本训练前（实验1）或在逆向水迷宫空间任务期间（实验2），每天向大鼠背侧纹状体注射不同剂量（0、0.05、0.5或5微克/0.5微升）的[3H]-[D-丙氨酸2，甲基苯丙氨酸4，甘醇5]-脑啡肽（DAMGO）。在两个实验中，在无药物的情况下进行探针保留测试。实验1的结果表明，与对照组相比，纹状体内注射低剂量DAMGO（0.05）导致空间学习能力增强，而高剂量（5.0）则产生损害。在探针测试期间，低剂量组比对照组表现出更好的平台位置记忆，以及改变搜索策略的能力增强。在实验2中，预训练减轻了实验1中发现的高剂量损害，表明该组存在运动损害。与所有其他组相比，低剂量组在探针测试期间继续表现出改变搜索策略的能力增强。数据表明，低剂量的DAMGO注射到背侧纹状体中时，消除了与海马体的竞争，从而导致空间处理能力增强。或者，对斑块-纹状体神经元的抑制可能会减弱记忆衰退过程。对这两种可能性都进行了讨论。
