Papa M, Segal M
Department of Neurobiology, Weizmann Institute, Rehovot, Israel.
Neuroscience. 1996 Apr;71(4):1005-11. doi: 10.1016/0306-4522(95)00490-4.
Rat hippocampal neurons, grown in dissociated culture for about 18 days, were exposed for 6 h to three days to stimuli which cause either an increase (GABAA antagonists, bicuculline or picrotoxin), or decrease (tetrodotoxin) in spontaneous neuronal activity. Individual neurons were stained with 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanine perchlorate and visualized with a confocal laser scanning microscope. GABA antagonists caused a marked, up to 60%, increase in spine density on secondary dendrites of cultured hippocampal neurons. This was associated with a small decrease in spine length. The rise in spine density was partially prevented by treatment with the calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetra-acetate, or by blockade of protein synthesis with cycloheximide. Tetrodotoxin caused a marked elongation of dendritic spines (but did not cause a decrease in spine density comparable to the increase caused by picrotoxin). This effect was seen primarily but not exclusively in spines with no distinct head. Both treatments were most effective within 24 h of exposure. There were no other systematic effects of the drugs on the morphology of the dendritic spines. These results indicate that dendritic spines in cultured neurons depend on ongoing synaptic activity to maintain their shape, and that neurons respond to an increase in synaptic demand by an increase in spine density. Thus, dendritic spines are likely to have a role in short-term synaptic interaction rather than to constitute a long-term memory storage device.
在解离培养中生长约18天的大鼠海马神经元，暴露于能引起自发神经元活动增加（GABAA拮抗剂、荷包牡丹碱或印防己毒素）或减少（河豚毒素）的刺激物中6小时至3天。单个神经元用高氯酸1,1'-二辛基-3,3,3',3'-四甲基吲哚碳菁染色，并用共聚焦激光扫描显微镜观察。GABAA拮抗剂使培养的海马神经元二级树突上的棘密度显著增加，增幅高达60%。这与棘长度的小幅减少有关。用钙螯合剂1,2-双（2-氨基苯氧基）乙烷-N,N,N,N-四乙酸处理或用环己酰亚胺阻断蛋白质合成可部分阻止棘密度的增加。河豚毒素使树突棘显著延长（但未导致棘密度像印防己毒素引起的增加那样减少）。这种效应主要但并非仅在没有明显头部的棘中可见。两种处理在暴露后24小时内最为有效。药物对树突棘形态没有其他系统性影响。这些结果表明，培养神经元中的树突棘依赖于持续的突触活动来维持其形状，并且神经元通过增加棘密度来响应突触需求的增加。因此，树突棘可能在短期突触相互作用中起作用，而不是构成长期记忆存储装置。
