Wossink J, Karst H, Mayboroda O, Joëls M
Swammerdam Institute of Life Sciences, University of Amsterdam, Kruislaan 320, 1098 SM Amsterdam, The Netherlands.
Neuroscience. 2001;108(2):263-72. doi: 10.1016/s0306-4522(01)00414-6.
After complete adrenalectomy, part of the granule cells in the dentate gyrus undergo apoptosis. Findings on morphological changes in non-apoptotic granule cells, though, have been equivocal. In the present study we examined the dendritic trees of dentate granule cells 7 days after adrenalectomy or sham operation, and tested the hypothesis that changes in dendritic trees have considerable consequences for ionic currents, as measured in the soma with whole cell recording. For the latter, we focussed on voltage-gated calcium currents, which are partly generated in distal dendrites. All cells were passively filled with a fluorescent dye via the patch pipette while recording calcium currents; subsequently the cells were three-dimensionally reconstructed with the use of a confocal microscope. In sham-operated rats, dendritic trees of cells with a soma located in the inner part of the granule cell layer (facing the hilus) were significantly smaller than trees of cells located in the outer part of the layer. Neurons from rats that had extremely low (undetectable-0.3 microg/dl) circulating levels of corticosterone displayed very small and simple dendritic trees compared to cells from adrenalectomized rats that still had residual levels of corticosterone (0.6-1.0 microg/dl), regardless of the location of their soma. Despite the observation that simple dendritic trees were seen in rats where corticosterone was extremely low, the whole cell calcium current amplitude recorded from the soma of these cells was not reduced compared to the remaining cells from adrenalectomized or sham-operated rats. Our data indicate that in the absence of corticosterone dendritic trees of dentate granule cells display atrophy but that this does not necessarily reduce ionic currents measured in the soma.
完全肾上腺切除术后，齿状回中的部分颗粒细胞会发生凋亡。然而，关于未凋亡颗粒细胞形态变化的研究结果并不明确。在本研究中，我们检查了肾上腺切除或假手术后7天齿状颗粒细胞的树突，并测试了以下假设：树突的变化对离子电流有重大影响，这可以通过全细胞记录在细胞体中测量。对于后者，我们重点研究了电压门控钙电流，其部分在远端树突中产生。在记录钙电流时，所有细胞都通过膜片吸管被动填充荧光染料；随后，使用共聚焦显微镜对细胞进行三维重建。在假手术大鼠中，细胞体位于颗粒细胞层内部（朝向门区）的细胞的树突明显小于位于该层外部的细胞的树突。与仍有残余皮质酮水平（0.6 - 1.0微克/分升）的肾上腺切除大鼠的细胞相比，循环皮质酮水平极低（不可检测 - 0.3微克/分升）的大鼠的神经元显示出非常小且简单的树突，无论其细胞体的位置如何。尽管观察到在皮质酮极低的大鼠中看到了简单的树突，但与肾上腺切除或假手术大鼠的其余细胞相比，从这些细胞的细胞体记录的全细胞钙电流幅度并未降低。我们的数据表明，在没有皮质酮的情况下，齿状颗粒细胞的树突会出现萎缩，但这不一定会降低在细胞体中测量的离子电流。
