Korkotian E, Segal M
Department of Neurobiology, The Weizmann Institute, Rehovot 76100, Israel.
J Neurosci. 2001 Aug 15;21(16):6115-24. doi: 10.1523/JNEUROSCI.21-16-06115.2001.
Regulation of dendritic spine motility was studied in dissociated cultures of the rat and mouse hippocampus, using green fluorescent protein-labeled neurons or neurons loaded with the calcium-sensitive dye Oregon Green-1. Cells were time-lapse-photographed on a confocal laser-scanning microscope at high resolution to detect movements as well as spontaneous fluctuations of intracellular calcium concentrations in their dendritic spines. Active presynaptic terminals attached to the spines were labeled with FM4-64, which marks a subset of synaptophysin-labeled terminals. Dendritic spines were highly motile in young, 4- to 7-d-old cells. At this age, neurons had little spontaneous calcium fluctuation or FM4-64 labeling. Within 2-3 weeks in culture, dendritic spines were much less motile, they were associated with active presynaptic terminals, and they expressed high rates of spontaneous calcium fluctuations. Irrespective of age, and even on the same dendrite, there was an inverse relationship between spine motility and presence of FM4-64-labeled terminals in contact with the imaged spines. Spine motility was blocked by latrunculin, which prevents actin polymerization, and was disinhibited by blockade of action potential discharges with tetrodotoxin. It is proposed that an active presynaptic terminal restricts motility of dendritic spines.
利用绿色荧光蛋白标记的神经元或加载钙敏染料 Oregon Green-1 的神经元，在大鼠和小鼠海马体的解离培养物中研究树突棘运动的调节。在共聚焦激光扫描显微镜下对细胞进行高分辨率的延时拍摄，以检测其树突棘的运动以及细胞内钙浓度的自发波动。附着在棘上的活跃突触前终末用 FM4-64 标记，FM4-64 标记了突触素标记终末的一个子集。在 4 至 7 日龄的年轻细胞中，树突棘具有高度的运动性。在这个年龄段，神经元几乎没有自发的钙波动或 FM4-64 标记。在培养 2 至 3 周内，树突棘的运动性大大降低，它们与活跃的突触前终末相关联，并且表现出高频率的自发钙波动。无论年龄如何，甚至在同一树突上，成像棘的运动性与接触的 FM4-64 标记终末的存在之间都存在反比关系。树突棘的运动被抑制肌动蛋白聚合的Latrunculin阻断，并被河豚毒素对动作电位发放的阻断所解除抑制。有人提出，活跃的突触前终末会限制树突棘的运动性。
