In vitro and in vivo physiology of low nanomolar concentrations of Zn(2+) in artificial cerebrospinal fluid.
In vitro and in vivo physiology of low nanomolar concentrations of Zn(2+) in artificial cerebrospinal fluid.
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DOI：
10.1038/srep42897
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发表时间：
2017-02-17
影响因子：
4.6
通讯作者：
Takeda A
中科院分区：
文献类型：
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作者：
Tamano H;Nishio R;Shakushi Y;Sasaki M;Koike Y;Osawa M;Takeda A
人工脑脊液（ACSF），即脑细胞外介质，包含 Ca2+ 和 Mg2+，但不包含其他二价阳离子，如 Zn2+，已用于体外和体内实验。本研究探讨 ACSF 中细胞外 Zn2+ 的生理意义。在含有 10nM ZnCl2 的 ACSF 中沐浴的幼鼠脑切片的透明层中，自发的突触前活动受到抑制，表明细胞外 Zn2+ 改变了海马突触前活动。为了检查 10nM ZnCl2 对长时程增强 (LTP) 的体内作用，使用连接到微透析探针的记录电极灌注记录区域。与灌注不含 Zn2+ 的 ACSF 相比，灌注含有 10nM ZnCl2 的 ACSF 并未改变年轻大鼠的 LTP 强度，但灌注含有 100nM ZnCl2 的 ACSF 会减弱 LTP 的强度。有趣的是，即使灌注含有 100nM ZnCl2 的 ACSF，老年大鼠的 LTP 强度也没有改变，但灌注含有 10mM CaEDTA（一种细胞外 Zn2+ 螯合剂）的 ACSF 却增强了 LTP 的强度。本研究表明，细胞外 Zn2+ 的基础水平（处于低纳摩尔浓度范围内）对于突触活动至关重要，并且可能会随着年龄的增长而增加。
Artificial cerebrospinal fluid (ACSF), i.e., brain extracellular medium, which includes Ca2+ and Mg2+, but not other divalent cations such as Zn2+, has been used for in vitro and in vivo experiments. The present study deals with the physiological significance of extracellular Zn2+ in ACSF. Spontaneous presynaptic activity is suppressed in the stratum lucidum of brain slices from young rats bathed in ACSF containing 10 nM ZnCl2, indicating that extracellular Zn2+ modifies hippocampal presynaptic activity. To examine the in vivo action of 10 nM ZnCl2 on long-term potentiation (LTP), the recording region was perfused using a recording electrode attached to a microdialysis probe. The magnitude of LTP was not modified in young rats by perfusion with ACSF containing 10 nM ZnCl2, compared to perfusion with ACSF without Zn2+, but attenuated by perfusion with ACSF containing 100 nM ZnCl2. Interestingly, the magnitude of LTP was not modified in aged rats even by perfusion with ACSF containing 100 nM ZnCl2, but enhanced by perfusion with ACSF containing 10 mM CaEDTA, an extracellular Zn2+ chelator. The present study indicates that the basal levels of extracellular Zn2+, which are in the range of low nanomolar concentrations, are critical for synaptic activity and perhaps increased age-dependently.