Department of Neuroscience and Cell Biology, University of Texas Medical Branch, 301 University Blvd., Galveston, TX 77555, USA.
J Neurosci Methods. 2012 Jan 15;203(1):146-51. doi: 10.1016/j.jneumeth.2011.09.008. Epub 2011 Sep 16.
Aberrant central nervous system zinc homeostasis has been reported in Alzheimer's disease (AD). However, there are conflicting reports describing zinc concentration either increased or decreased in the brain of AD patients. Such discrepancies may be due to differences in the brain area examined, zinc detection method, and/or tissue composition. Furthermore, detection and measurement of the releasable zinc pool in autopsy tissue is difficult and usually unreliable. Obtaining an adequate assessment of this releasable zinc pool is of particular significance in AD research in that zinc can coordinate with and stabilize toxic amyloid beta oligomers, which are believed to play a key role in AD neuropathology. In addition, zinc released into the synaptic cleft can interact with the postsynaptic neurons causing altered signaling and synaptic dysfunction, which is a well established event in AD. The method presented here combines two approaches, biochemical fractionation and atomic absorption spectrophotometry, to allow, in addition to extracellular zinc concentration, the reliable and quantitative measurement of zinc specifically localized in synaptic vesicles, which contain the majority of the neuronal releasable zinc. Using this methodology, we found that synaptic vesicle zinc concentrations were increased in AD hippocampi compared to age-matched controls and that this increase in releasable zinc matched increased concentration of zinc in the extracellular space.
中枢神经系统锌稳态异常已在阿尔茨海默病（AD）中报道。然而，有一些相互矛盾的报告描述 AD 患者大脑中的锌浓度增加或减少。这种差异可能是由于所检查的脑区、锌检测方法和/或组织成分的不同所致。此外，在尸检组织中检测和测量可释放锌池是困难的，通常不可靠。在 AD 研究中，获得对这种可释放锌池的充分评估具有特别重要的意义，因为锌可以与有毒的淀粉样β寡聚物协调并稳定，淀粉样β寡聚物被认为在 AD 神经病理学中发挥关键作用。此外，释放到突触间隙中的锌可以与突触后神经元相互作用，导致信号改变和突触功能障碍，这是 AD 中的一个既定事件。这里提出的方法结合了两种方法，即生化分级分离和原子吸收分光光度法，除了可以测量细胞外锌浓度外，还可以可靠地定量测量特别定位于包含大多数神经元可释放锌的突触小泡中的锌。使用这种方法，我们发现与年龄匹配的对照组相比，AD 海马中的突触小泡锌浓度增加，并且这种可释放锌的增加与细胞外空间中锌浓度的增加相匹配。
