Wong T P, Campbell P M, Ribeiro-da-Silva A, Cuello A C
Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada.
Neuroscience. 1998 May;84(2):403-12. doi: 10.1016/s0306-4522(97)00485-5.
In this study, we have investigated the changes in the number of individual presynaptic boutons in the neocortex of rats and correlated them with cognitive performance. Brown Norway x Fischer 344 F1 hybrid rats, aged from one to 24 months, were used. Using synaptophysin as a marker for presynaptic boutons, we found that in the parietal II region of the neocortex an age-related decrease in the density of immunostained punctae representing presynaptic boutons occurred. Regression analysis showed that this decline in the number of presynaptic boutons correlates with ageing (r=0.495, P<0.05). Interestingly, we found that this age-related depletion of presynaptic boutons was more intense in the deeper cortical lamina, such as laminae V and VI (mean decrease of 18%), than in the superficial laminae (mean decrease of 8% in laminae I-IV). Using the Morris water maze test, we observed that young rats acquired the task at twice the speed of aged animals (48.9 +/- 9.0 s and 91.0 +/- 4.9 s for young and aged animals, respectively). Furthermore, at the end of the training period, the aged cohort still showed significantly higher escape latencies in the Morris water maze. The present findings support the concept that the decline in cognitive performances in ageing is related to the loss of synapses in the cerebral cortex.
在本研究中，我们调查了大鼠新皮质中单个突触前终扣数量的变化，并将其与认知表现相关联。使用了年龄在1至24个月的棕色挪威大鼠×费希尔344大鼠F1杂交种。以突触素作为突触前终扣的标志物，我们发现在新皮质的顶叶II区，代表突触前终扣的免疫染色斑点密度出现与年龄相关的下降。回归分析表明，突触前终扣数量的这种下降与衰老相关（r = 0.495，P < 0.05）。有趣的是，我们发现这种与年龄相关的突触前终扣减少在皮质深层板层（如V层和VI层）更为明显（平均减少18%），而在浅层板层（I-IV层平均减少8%）则不那么明显。使用莫里斯水迷宫试验，我们观察到年轻大鼠完成任务的速度是老年动物的两倍（年轻和老年动物分别为48.9±9.0秒和91.0±4.9秒）。此外，在训练期结束时，老年组在莫里斯水迷宫中的逃避潜伏期仍显著更高。目前的研究结果支持了衰老过程中认知能力下降与大脑皮质突触丧失有关的观点。
