Homeostatic maintenance in excitability of tree shrew hippocampal CA3 pyramidal neurons after chronic stress
Homeostatic maintenance in excitability of tree shrew hippocampal CA3 pyramidal neurons after chronic stress
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DOI：
10.1002/hipo.10212
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发表时间：
2004-01-01
期刊：
影响因子：
3.5
通讯作者：
Fuchs, E
中科院分区：
文献类型：
--
作者：
Kole, MHP;Czéh, B;Fuchs, E
慢性应激诱导海马CA3顶神经元树突可逆退化。虽然这种突触后膜的减少会明显减少突触输入的可能性，但对这些细胞的功能性膜特性的影响尚不清楚。我们检验了慢性应激影响CA3锥体细胞的输入输出特性和兴奋性的假设。研究人员利用平行胞内生物细胞素标记技术对雄性树鼩体外海马切片的CA3神经元进行了体细胞全细胞电流钳记录，这些切片是在社会心理应激暴露28天后收集的，并与对照动物的记录进行了比较。生物细胞素标记的CA3细胞的事后形态计量学分析显示分支退化，通过更少的树突交叉和长度，仅限于与体细胞相似的280-340 mum的距离。全细胞记录的结果表明，慢性应激令人惊讶地降低了20-25%的表观膜时间常数和输入电阻，并伴随着超极化引起的电压“凹陷”幅度的增加。所有活性膜特性，包括去极化诱导的动作电位动力学、复杂的尖峰模式和超极化后的电压，都与对照记录无法区分。尽管线性关联分析证实，几何形状的差异，如根尖长度或分支数，与AP电流和电压阈值特性的功能变化相关，但这些变化太过微小，无法反映在组间差异中。然而，个体肾上腺激素状态与阈下兴奋性的选择性变化显著相关。综上所述，这些数据证明，尽管长期应激导致CA3锥体神经元的形态改变、皮质醇释放上调和固有膜特性改变，但CA3锥体神经元的躯体兴奋性的作用在很大程度上得到了保留。(C) 2004 Wiley-Liss, Inc。
The experience of chronic stress induces a reversible regression of hippocampal CA3 apical neuron dendrites. Although such postsynaptic membrane reduction will obviously diminish the possibility of synaptic input, the consequences for the functional membrane properties of these cells are not well understood. We tested the hypothesis that chronic stress affects the input-output characteristics and excitability of CA3 pyramidal cells. Somatic whole-cell current-clamp recording with parallel intracellular biocytin labeling was performed on CA3 neurons from in vitro hippocampal slices from male tree shrews, which were collected after 28 days of psychosocial stress exposure and compared to recordings obtained from control animals. Post hoc morphometric analysis of biocytin-labeled CA3 cells revealed branch regression, by fewer dendritic crossings and length, limited to a distance of similar to280-340 mum from the soma only. The results from whole-cell recording indicate that chronic stress surprisingly reduced the apparent membrane time constant and input resistance 20-25%, accompanied by increased amplitude of the hyperpolarization-induced voltage "sag." All active membrane properties, including depolarization-induced action potential kinetics, complex spiking patterns, and afterhyperpolarization voltages, were indistinguishable from control recordings. Although linear association analysis confirmed that differences in geometry, such as apical length or branch number, were correlated to functional variability in properties of the AP current and voltage threshold, these changes were too marginal to be reflected in the group differences. However, the individual adrenal hormone status was associated significantly with the selective changes in subthreshold excitability. Taken together, the data provide evidence that despite long-term stress induces morphological changes, upregulates cortisol release and shifts the intrinsic membrane properties, the efficacy of somatic excitability of CA3 pyramidal neurons is largely preserved. (C) 2004 Wiley-Liss, Inc.