Impact of Aging on Proprioceptive Sensory Neurons and Intrafusal Muscle Fibers in Mice.
Impact of Aging on Proprioceptive Sensory Neurons and Intrafusal Muscle Fibers in Mice.
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衰老对小鼠本体感觉神经元和梭内肌纤维的影响。
DOI：
10.1093/gerona/glw175
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Valdez,Gregorio
中科院分区：
文献类型：
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作者：
Vaughan,SydneyK;Stanley,OliviaL;Valdez,Gregorio
老化对本体感觉神经元和梭内肌纤维（IMF）的影响仍然在很大程度上未被探索，尽管这些细胞在调节随意运动中发挥着重要作用。在这里，我们表明，本体感觉神经元在中年（11至13个月大）和老年（15至21个月大）小鼠中发生有害的形态学变化。在伸趾长肌和比目鱼肌的中年和老年小鼠，有一个显着增加的数量Ia传入与大的sediments未能正确地包裹周围IMF相比，年轻的成年（2至4个月大）小鼠。在中年和老年小鼠的相同肌肉中也发现较少的II传入。虽然这些年龄相关的变化，周围神经末梢伴随着退变的本体感觉神经元胞体在背根神经节（DRG），IMF的形态和数量保持不变。我们的分析还显示，正常水平的神经营养因子3（NT 3），但酪氨酸激酶受体C（TrkC）的表达失调，分别在老年肌肉和DRG。这些结果表明，本体感受感觉神经元退化之前，老化过程中的IMF萎缩，并在NT 3/TrkC信号传导轴的存在下。
The impact of aging on proprioceptive sensory neurons and intrafusal muscle fibers (IMFs) remains largely unexplored despite the central function these cells play in modulating voluntary movements. Here, we show that proprioceptive sensory neurons undergo deleterious morphological changes in middle age (11- to 13-month-old) and old (15- to 21-month-old) mice. In the extensor digitorum longus and soleus muscles of middle age and old mice, there is a significant increase in the number of Ia afferents with large swellings that fail to properly wrap around IMFs compared with young adult (2- to 4-month-old) mice. Fewer II afferents were also found in the same muscles of middle age and old mice. Although these age-related changes in peripheral nerve endings were accompanied by degeneration of proprioceptive sensory neuron cell bodies in dorsal root ganglia (DRG), the morphology and number of IMFs remained unchanged. Our analysis also revealed normal levels of neurotrophin 3 (NT3) but dysregulated expression of the tyrosine kinase receptor C (TrkC) in aged muscles and DRGs, respectively. These results show that proprioceptive sensory neurons degenerate prior to atrophy of IMFs during aging, and in the presence of the NT3/TrkC signaling axis.