McNay Ewan C, Canal Clinton E, Sherwin Robert S, Gold Paul E
Section of Endocrinology, Yale University School of Medicine, USA.
Physiol Behav. 2006 Feb 28;87(2):298-303. doi: 10.1016/j.physbeh.2005.10.016. Epub 2005 Dec 15.
The concentration of glucose in the extracellular fluid (ECF) of the hippocampus decreases substantially during memory testing on a hippocampus-dependent memory task. Administration of exogenous glucose, which enhances task performance, prevents this decrease, suggesting a relationship between hippocampal glucose availability and memory performance. In the present experiment, spontaneous alternation performance and task-related changes in hippocampal ECF glucose were assessed in rats after intraseptal administration of morphine, which impairs memory on a spontaneous alternation task, and after co-administration of intraseptal glucose, which attenuates that impairment. Consistent with previous findings, spontaneous alternation testing resulted in a decrease in hippocampal ECF glucose levels in control rats. However, rats that received intraseptal morphine prior to testing showed memory impairments and an absence of the task-related decrease in hippocampal ECF glucose levels. Intraseptal co-administration of glucose with morphine attenuated the memory impairment, and ECF glucose levels in the hippocampus decreased in a manner comparable to that seen in control rats. These data suggest that fluctuations in hippocampal ECF glucose levels may be a marker of mnemonic processing and support the view that decreases in extracellular glucose during memory testing reflect increased glucose demand during memory processing.
在依赖海马体的记忆任务的记忆测试过程中，海马体细胞外液（ECF）中的葡萄糖浓度会大幅下降。给予外源性葡萄糖可提高任务表现，并能防止这种下降，这表明海马体葡萄糖供应与记忆表现之间存在关联。在本实验中，对大鼠进行了中隔内注射吗啡（这会损害其在自发交替任务中的记忆）以及中隔内联合注射葡萄糖（这会减轻该损害）后，评估了大鼠的自发交替表现以及海马体ECF葡萄糖的任务相关变化。与先前的研究结果一致，自发交替测试导致对照大鼠的海马体ECF葡萄糖水平下降。然而，在测试前接受中隔内吗啡注射的大鼠出现了记忆损害，且海马体ECF葡萄糖水平没有出现与任务相关的下降。中隔内将葡萄糖与吗啡联合注射可减轻记忆损害，并且海马体中的ECF葡萄糖水平下降的方式与对照大鼠中观察到的情况相当。这些数据表明，海马体ECF葡萄糖水平的波动可能是记忆加工的一个标志，并支持这样一种观点，即记忆测试期间细胞外葡萄糖的减少反映了记忆加工过程中葡萄糖需求的增加。
