Dynamics in the ultrastructure of asymmetric axospinous synapses in the frontal cortex of hibernating European ground squirrels (Spermophilus citellus)
Dynamics in the ultrastructure of asymmetric axospinous synapses in the frontal cortex of hibernating European ground squirrels (Spermophilus citellus)
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DOI：
10.1002/syn.20380
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发表时间：
2007-05-01
期刊：
影响因子：
2.3
通讯作者：
Hut, R. A.
中科院分区：
文献类型：
--
作者：
Ruediger, J.;Van der Zee, E. A.;Hut, R. A.
最近关于冬眠哺乳动物从昏睡中唤醒的功能的理论集中在对长时间低温累积的损伤的中枢神经系统的修复上。在这个框架内，我们研究了突触超微结构在第2层的额叶皮层冬眠的欧洲地松鼠（黄鼠）牺牲在四个不同阶段的torporarousal周期。使用电子显微镜，我们量化的突触数量和形态测量数据的不对称轴棘突触。测量突触后致密物（PSD）的长度、宽度和表面积，以及所分析突触的突触并置长度。在进入麻痹（早期麻痹，TE，n = 6）、晚期麻痹（晚期麻痹，TL，n = 5）、正常体温觉醒发作开始（早期觉醒，AE，n = 5）、正常体温觉醒发作晚期（晚期觉醒，AL，n = 5）和春季持续正常体温期间（EU，n = 6）比较五组动物。结果表明，在麻痹和觉醒开始时，PSD长度和突触并置长度显着增加，相比，在觉醒后期和春季条件下的突触。相反，PSD的宽度和表面积在休眠状态下减小。在觉醒开始时，PSD的宽度增加，并在晚觉醒（AL）中获得最大值，返回到弹簧（EU）值。在休眠-觉醒周期中，突触总数没有差异。结果表明，可逆的变化（不对称轴棘）突触在额叶皮层，这可能是至关重要的皮层神经元网络的维护和保护对潜在的有害影响的长期低温阶段的冬眠超微结构。
Recent theories on the function of arousals from torpor in hibernating mammals focus on the repair of the central nervous system from damage accumulating during prolonged hypothermia. In this framework, we investigated the synaptic ultrastructure in Layer 2 of the frontal cortex from hibernating European ground squirrels (Spermophilus citellus) sacrificed at four different phases in the torporarousal cycle. Using electron microscopy, we quantified synapse number and morphometric data on asymmetric axospinous synapses. Length, width, and surface area of postsynaptic densities (PSDs), and the synaptic apposition length of the analyzed synapse were measured. Five groups of animals were compared during entrance into torpor (Torpor Early, TE, n = 6), late torpor (Torpor Late, TL, n = 5), beginning of euthermic arousal episodes (Arousal Early, AE, n = 5), late in the euthermic arousal episode (Arousal Late, AL, n = 5), and during continuous euthermy in spring (EU, n = 6). The results showed that during torpor and at the beginning of arousals the PSD length and synaptic apposition length are significantly increased compared to synapses during late arousal and in spring conditions. In contrast, the width and surface area of the PSDs are decreased in torpor. At the beginning of an arousal the width of the PSD increases and gains maximum value in late arousals (AL), returning to spring (EU) values. No differences were found in total number of synapses during the torpor-arousal cycle. The results indicate reversible changes in ultrastructure of (asymmetric axospinous) synapses in the frontal cortex, which may be critical for the maintenance of cortical neuronal networks and for protection against potential deleterious effects of prolonged hypothermic phases of hibernation.