Roberge M-C, Messier C, Staines W A, Plamondon H
University of Ottawa, School of Psychology, 11, Marie Curie, Vanier Building Room 204, Ottawa, ON, Canada K1N 9A4.
Neuroscience. 2008 Sep 22;156(1):11-29. doi: 10.1016/j.neuroscience.2008.05.062. Epub 2008 Jul 25.
Food restriction has been shown to be beneficial for a number of brain processes. In the current study, we characterized the impact of food restriction on hippocampal damage 70 days following ischemia. We assessed memory and cognitive flexibility of ad libitum fed (AL) and food-restricted (FR) animals using complex delayed non-matching- and matching-to-sample tasks in the radial arm maze. Our findings demonstrate that food restriction led to significant improvement of ischemia-induced memory impairments. FR ischemic animals rapidly reached comparable performance as both AL and FR sham animals in delayed-non-matching (win-shift) and matching (win-stay) radial arm maze tasks. They also made considerably fewer microchoices in the retention trials than AL ischemic animals. In contrast, AL ischemic rats showed persistent spatial memory impairments in the same paradigms. Assessment of basal and stress-induced corticosterone (CORT) secretion revealed no significant differences in baseline levels in AL and FR rats prior to or following global ischemia. However, FR animals showed a more pronounced attenuation of CORT secretion 45 min following restraint. Both FR and AL ischemic rats had comparable cell loss within CA1 and CA3 subfields of Ammon's horn (CA1 and CA3) at 70 days following reperfusion, although a trend toward increased CA3 cell survival was observed in FR ischemic rats. The functional sparing in the FR ischemic animals in the face of equivalent hippocampal cell loss suggests that food restriction somehow enhanced the efficacy of remaining hippocampal or extrahippocampal neurons following ischemia. In the current study, this phenomenon was not associated with diet- and or ischemia-related alterations of vesicular glutamate transporter 1 expression in various hippocampal regions although lower vesicular GABA transporter immunostaining was present in the CA1 stratum oriens and the CA3 stratum radiatum in FR sham and ischemic rats.
食物限制已被证明对许多大脑过程有益。在当前的研究中,我们描述了食物限制对缺血70天后海马损伤的影响。我们使用放射状臂迷宫中的复杂延迟非匹配和匹配样本任务,评估了自由进食(AL)和食物限制(FR)动物的记忆和认知灵活性。我们的研究结果表明,食物限制导致缺血诱导的记忆障碍有显著改善。FR缺血动物在延迟非匹配(赢-转换)和匹配(赢-停留)放射状臂迷宫任务中,迅速达到了与AL和FR假手术动物相当的表现。在保持试验中,它们做出的微选择也比AL缺血动物少得多。相比之下,AL缺血大鼠在相同的范式中表现出持续的空间记忆障碍。对基础和应激诱导的皮质酮(CORT)分泌的评估显示,在全脑缺血之前或之后,AL和FR大鼠的基线水平没有显著差异。然而,FR动物在束缚后45分钟时CORT分泌的衰减更为明显。再灌注70天后,FR和AL缺血大鼠在海马角(CA1和CA3)的CA1和CA3亚区内的细胞损失相当,尽管在FR缺血大鼠中观察到CA3细胞存活增加的趋势。面对同等程度的海马细胞损失,FR缺血动物的功能保留表明,食物限制以某种方式增强了缺血后剩余海马或海马外神经元的功效。在当前的研究中,尽管在FR假手术和缺血大鼠的CA1原层和CA3辐射层中,囊泡GABA转运体免疫染色较低,但这种现象与不同海马区域中囊泡谷氨酸转运体1表达的饮食和/或缺血相关改变无关。