Laboratorio de Psicobiología, División de Neurociencias, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Guadalajara, Jal., Mexico.
Laboratorio de Neurofisiología Experimental, CIBIMI, Instituto Mexicano del Seguro Social, Morelia, Mich., Mexico.
Neurobiol Learn Mem. 2014 Mar;109:94-103. doi: 10.1016/j.nlm.2013.11.017. Epub 2013 Dec 5.
Normal aging is characterized by slight impairments in spatial memory, and the modification of some electrophysiological parameters that underlie place learning and associated reference memory. However, the morphological mechanisms underlying these impairments remain unknown. In the present study, we analyzed the spine density and the proportion of thin, mushroom, stubby, wide, branched and double spines on pyramidal neuron dendrites in the hippocampal CA1 field of young and aged rats. These parameters were assessed both before and after evaluating place learning and reference memory in the Morris water maze. Aged rats adopted an egocentric strategy to resolve the task, swimming slower and further, and taking longer to locate the sunken platform. While probe trials revealed that aged animals could recall the platform position, these animals spent more time exploring incorrect quadrants than young rats. An increase in spine density was observed after task performance in both young and aged rats, but aging provoked a decrease in the density of thin spines. In addition, there was an increase in the density of mushroom and wide spines in aged animals after task performance as compared with the untested aged counterparts. Moreover, in aged animals there were fewer thin spines and more wide spines after task performance than in the young tested animals. These findings support the view that aging attenuates but does not abolish spatial memory, a process that may be associated with plastic changes in the type of dendritic spines on aged hippocampal CA1 neurons.
正常衰老的特点是空间记忆略有损伤，以及一些基础位置学习和相关参照记忆的电生理参数的改变。然而，这些损伤背后的形态学机制仍不清楚。在本研究中，我们分析了年轻和老年大鼠海马 CA1 区锥体神经元树突上的棘密度和薄棘、蘑菇棘、短棘、宽棘、分支棘和双棘的比例。这些参数在评估 Morris 水迷宫中的位置学习和参照记忆之前和之后都进行了评估。老年大鼠采用以自我为中心的策略来解决任务，游泳速度较慢，游得更远，找到下沉平台的时间也更长。虽然探测试验表明老年动物可以回忆起平台的位置，但这些动物在探索错误象限上花费的时间比年轻大鼠多。在完成任务后，年轻和老年大鼠的棘密度都有所增加，但衰老会导致薄棘密度降低。此外，与未经测试的老年大鼠相比，老年动物在完成任务后蘑菇棘和宽棘的密度增加。此外，与年轻的测试动物相比，老年动物在完成任务后薄棘减少，宽棘增多。这些发现支持这样一种观点，即衰老虽然减弱但并未完全消除空间记忆，这一过程可能与老年海马 CA1 神经元树突棘的类型发生可塑性变化有关。
