In Vivo Volume Dynamics of Dendritic Spines in the Neocortex of Wild-Type and Fmr1 KO Mice.
In Vivo Volume Dynamics of Dendritic Spines in the Neocortex of Wild-Type and Fmr1 KO Mice.
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DOI：
10.1523/eneuro.0282-18.2018
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发表时间：
2018-09
期刊：
影响因子：
3.4
通讯作者：
Kasai H
中科院分区：
文献类型：
--
作者：
Ishii K;Nagaoka A;Kishida Y;Okazaki H;Yagishita S;Ucar H;Takahashi N;Saito N;Kasai H
在大多数投射神经元中，兴奋性突触通常形成于树突的小突起，称为树突棘，棘头体积与突触连通性有很强的相关性。我们使用共振电偶扫描仪的延时体内双光子成像检查了成年小鼠视觉皮层中脊柱体积的动态变化。与预期相反，我们发现成人新皮质的棘表现出与年轻海马准备中观察到的相似程度的波动，但在动力学如何依赖于棘体积方面存在系统差异，因此允许小棘的波动较少，这可以解释体内新皮质棘的相对较低的周转率。我们发现脆性X智力迟钝小鼠模型（Fmr1敲除）的脊柱体积波动比野生型小鼠更大，Fmr1敲除小鼠的脊柱周转率也更高。在我们的模型中，Fmr1敲除小鼠脊柱动力学的这些特征可以用一个斜率因子来表示。我们的数据和模型表明，Fmr1敲除小鼠的平均脊柱体积变化虽小但显著，即使在成年期，统计分布的差异也更为显著，这反映了脊柱体积在体内的异常动态。
Excitatory synapses are often formed at small protrusions of dendrite, called dendritic spines, in most projection neurons, and the spine-head volumes show strong correlations with synaptic connectivity. We examined the dynamics of spine volume in the adult mouse visual cortex using time-lapse in vivo two-photon imaging with a resonant Galvano scanner. Contrary to expectations, we found that the spines in the adult neocortex showed fluctuations to a similar degree as that observed in young hippocampal preparations, but there were systematic differences in how the dynamics were dependent on spine volumes, thus allowing for fewer fluctuations in small spines, which could account for the relatively low turnover rates of neocortical spines in vivo. We found that spine volumes fluctuated to a greater extent in a mouse model (Fmr1 knockout) of fragile X mental retardation than in wild-type mice, and the spine turnover rates were also higher in Fmr1 knock-out mice. Such features of spine dynamics in Fmr1 knock-out mice could be represented by a single slope factor in our model. Our data and model indicate a small but significant change in the average spine volume and more eminent differences in the statistical distribution in Fmr1 knock-out mice even in adulthood, which reflects the abnormal in vivo dynamics of spine volumes.