Ubiquitous and temperature-dependent neural plasticity in hibernators
Ubiquitous and temperature-dependent neural plasticity in hibernators
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DOI：
10.1523/jneurosci.2874-06.2006
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发表时间：
2006-10-11
影响因子：
5.3
通讯作者：
Heller, H. Craig
中科院分区：
文献类型：
--
作者：
von der Ohe, Christina G.;Darian-Smith, Corinna;Heller, H. Craig
冬眠的哺乳动物在大脑温度接近冰点和神经活动几乎停止的情况下存活了一周或更长时间。这种极端的生理状态与海马神经元的树突和突触变化有关。在这里，我们研究这些变化是否是由温度驱动的整个大脑中普遍存在的现象。我们用离子电渗法将荧光黄注射到冬眠的地松鼠的固定切片中的几种神经元中。我们分析了神经元显微结构的动物在几个阶段的麻痹在两个不同的环境温度，并在夏季。我们发现，神经元的细胞体，树突，从几种类型的细胞在冬眠的地松鼠收缩进入休眠状态，在几天的过程中变化不大，然后在2小时内重新生长返回到低温。海马、皮层和丘脑的神经元也发生了类似的结构变化，这表明这是一个全球性的现象。对不同环境温度下冬眠动物的神经显微结构的研究表明，神经回缩与最低体温之间存在线性关系。尽管显著的温度依赖性的差异，在休眠期间的收缩程度，恢复达到相同的最终值的细胞体面积，树突状乔木的复杂性，和棘密度。这项研究表明，在地面松鼠大脑麻痹期间，大规模和似乎无处不在的神经可塑性。它还定义了一个温度驱动的戏剧性神经可塑性模型，这为探索成年哺乳动物大规模再生的机制以及重塑对学习和记忆的影响提供了一个独特的机会。
Hibernating mammals are remarkable for surviving near-freezing brain temperatures and near cessation of neural activity for a week or more at a time. This extreme physiological state is associated with dendritic and synaptic changes in hippocampal neurons. Here, we investigate whether these changes are a ubiquitous phenomenon throughout the brain that is driven by temperature. We iontophoretically injected Lucifer yellow into several types of neurons in fixed slices from hibernating ground squirrels. We analyzed neuronal microstructure from animals at several stages of torpor at two different ambient temperatures, and during the summer. We show that neuronal cell bodies, dendrites, and spines from several cell types in hibernating ground squirrels retract on entry into torpor, change little over the course of several days, and then regrow during the 2 h return to euthermia. Similar structural changes take place in neurons from the hippocampus, cortex, and thalamus, suggesting a global phenomenon. Investigation of neural microstructure from groups of animals hibernating at different ambient temperatures revealed that there is a linear relationship between neural retraction and minimum body temperature. Despite significant temperature-dependent differences in extent of retraction during torpor, recovery reaches the same final values of cell body area, dendritic arbor complexity, and spine density. This study demonstrates large-scale and seemingly ubiquitous neural plasticity in the ground squirrel brain during torpor. It also defines a temperature-driven model of dramatic neural plasticity, which provides a unique opportunity to explore mechanisms of large-scale regrowth in adult mammals, and the effects of remodeling on learning and memory.