IMAGING CELL-VOLUME CHANGES AND NEURONAL EXCITATION IN THE HIPPOCAMPAL SLICE
IMAGING CELL-VOLUME CHANGES AND NEURONAL EXCITATION IN THE HIPPOCAMPAL SLICE
复制标题
DOI：
10.1016/0306-4522(94)90372-7
复制
发表时间：
1994-09-01
期刊：
影响因子：
3.3
通讯作者：
MACVICAR, BA
中科院分区：
文献类型：
--
作者：
ANDREW, RD;MACVICAR, BA
脑细胞肿胀是癫痫发作、局部缺血或兴奋性中毒的结果。皮质表面光反射的变化现在被用来监测大脑活动，但这些内在信号知之甚少。本研究的目的首先是表明透光率的变化与细胞体积相关，其次是成像透光率的增加，因为它们与神经元激活相关。来自大鼠的横向海马切片用于研究。短暂暴露（4-6分钟）于低渗人工脑脊液（~ 40 mOsm）在切片的大部分区域，特别是在CA 1树突状区域，持续且可逆地提高透光率。无论是零钙人工脑脊液，也没有河豚毒素改变透射率的增加和随后的逆转，这表明它是依赖于渗透压，但独立的突触传递和神经元放电。从Schaffer侧支诱发的CA 1群体尖峰的幅度随着透光率的低渗增加而增加，提供了细胞外组织电阻增加的证据。含有不渗透甘露醇的高渗人工脑脊液（+40 mOsm）始终降低透光率和群体峰值的幅度。渗透细胞的甘油（+40 mOsm）没有影响。两者合计，这些观察表明，渗透压的挑战改变光透射率诱导的变化，细胞volume.Transmittance增加低渗人工脑脊液或10 μ M红藻氨酸诱导的CA 1细胞体区域相比，树突状区域。类似地，顺向刺激终止于定向层或放射层的轴突引起的透射率仅在其各自的突触后区域增加。相反，细胞体区域及其邻近的近端-顶端树突（动作电位起始的两个位点）在短暂暴露于20 mM K+时可以显示透光率的急剧增加，该反应可能代表神经元损伤，在河豚毒素中被阻断。逆向刺激引起了弱的反应，在这些相同的近端areas.We的结论是，活动依赖性的增加，在整个脑切片的透光率主要揭示了神经胶质细胞和神经元肿胀与兴奋性突触输入和动作电位放电。该信号可以在真实的时间成像，以揭示神经元激活，不仅在海马区，但在神经元区域。细胞肿胀是神经元过度放电的已知结果。因此，在整个脑切片的光透射率的变化的成像应证明是有用的监测癫痫和兴奋性中毒状态。
Brain cell swelling is a consequence of seizure, ischemia or excitotoxicity. Changes in light reflectance from cortical surface are now used to monitor brain activity but these intrinsic signals are poorly understood. The objectives of this study were first, to show that changes in light transmittance were correlated with cell volume and second, to image increases in light transmittance as they related to neuronal activation. Transverse hippocampal slices from the rat were used for the study. Brief exposure (4-6 min) to hypo-osmotic artificial cerebrospinal fluid (-40 mOsm) elevated light transmittance consistently and reversibly in most regions of the slice and particularly in CA1 dendritic regions. Neither zero-Ca2+ artificial cerebrospinal fluid nor tetrodotoxin altered the transmittance increase and its subsequent reversal, suggesting that it was dependent on osmolality but independent of synaptic transmission and neuronal firing. The amplitude of the CA1 population spike evoked from Schaffer collaterals increased concomitantly with the hypo-osmotic increase in light transmittance, providing evidence that the extracellular tissue resistance increased. Hyper-osmotic artificial cerebrospinal fluid (+40 mOsm) containing impermeant mannitol consistently lowered light transmittance and the amplitude of the population spike. Glycerol (+40 mOsm), which is cell permeant, did not have an affect. Taken together these observations indicate that osmotic challenge alters light transmittance by inducing changes in cell volume.Transmittance increases induced by hypo-osmotic artificial cerebrospinal fluid or 10 mu M kainate were small in the CA1 cell body region compared to dendritic regions. Similarly, orthodromic stimulation of axons terminating in stratum oriens or in stratum radiatum evoked transmittance increases only in their respective postsynaptic areas. In contrast, the cell body region and its adjacent proximal-apical dendrites (both sites of action potential initiation) could display dramatic increases in light transmittance upon brief exposure to 20 mM K+, The response, which may represent neuronal damage, was blocked in tetrodotoxin. Antidromic stimulation evoked a weak response in these same proximal areas.We conclude that activity-dependent increases in light transmittance across brain slices primarily reveal glial and neuronal swelling associated with excitatory synaptic input and action potential discharge. The signal can be imaged in real time to reveal neuronal activation, not only among hippocampal areas, but among neuronal regions. Cell swelling is a known consequence of excessive neuronal discharge. Therefore, the imaging of changes in light transmittance across brain slices should prove useful in monitoring epileptiform and excitotoxic states.