Atapour Nafiseh, Rosa Marcello G P
Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia; Australian Research Council, Centre of Excellence for Integrative Brain Function, Monash University Node, Melbourne, Victoria, Australia.
Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia; Australian Research Council, Centre of Excellence for Integrative Brain Function, Monash University Node, Melbourne, Victoria, Australia.
Neurobiol Aging. 2017 Sep;57:95-103. doi: 10.1016/j.neurobiolaging.2017.05.013. Epub 2017 May 22.
Structural plasticity of the axon initial segment (AIS), the site of action potential initiation, is observed as part of the normal early development of the cortex, as well as in association with injury and disease. Here, we show that structural AIS plasticity also occurs with normal aging in adult marmosets. Immunohistochemical techniques were used to reveal the extent of the AIS of layer 2/3A pyramidal cells in 8 neocortical areas. We found that the AIS length varied significantly between areas in young adult (2-3 years old) marmosets, with neurons in frontal area 14C having the longest AIS, and those in the primary visual cortex the shortest. Similar interareal differences were observed in aged (12-14 year old) monkeys, but the AIS was significantly shortened in many areas, relative to the corresponding length in young adults. Shortening of the AIS is likely to represent a compensatory response to changes in the excitation-inhibition balance, associated with the loss of GABAergic interneurons in the aged cortex.
轴突起始段（AIS）是动作电位起始的部位，其结构可塑性在皮层正常早期发育过程中可以观察到，也与损伤和疾病相关。在此，我们表明，成年狨猴正常衰老过程中也会出现AIS结构可塑性。采用免疫组织化学技术揭示8个新皮层区域中第2/3A层锥体细胞的AIS范围。我们发现，在年轻成年（2 - 3岁）狨猴中，各区域之间的AIS长度差异显著，额叶14C区的神经元AIS最长，初级视觉皮层的最短。在老年（12 - 14岁）猴子中也观察到类似的区域间差异，但相对于年轻成年猴的相应长度，许多区域的AIS显著缩短。AIS缩短可能代表对兴奋 - 抑制平衡变化的一种代偿反应，这与老年皮层中GABA能中间神经元的丧失有关。
