Extrasynaptic volume transmission and diffusion parameters of the extracellular space
Extrasynaptic volume transmission and diffusion parameters of the extracellular space
复制标题
DOI：
10.1016/j.neuroscience.2004.06.077
复制
发表时间：
2004-01-01
期刊：
影响因子：
3.3
通讯作者：
Sykov치, E
中科院分区：
文献类型：
--
作者：
Sykov치, E
神经元或神经元与神经胶质细胞之间的突触外通讯是通过神经活性物质在细胞外间隙(ECS)中的扩散而介导的。ECS中扩散通道的大小和不规则几何形状不仅在单个细胞周围，而且在不同的中枢神经系统区域也有很大不同，从而影响和指导各种神经活性物质在ECS中的运动。因此，CNS中的扩散不仅是不均匀的，而且往往是各向异性的。成年哺乳动物(包括人类)的扩散参数、ECS体积分数α(α=ECS体积/总组织体积)和曲折波长(lambda(2)=自由/表观扩散系数)通常分别为0.20-0.25和1.5-1.6，因此阻碍了神经活性物质和水的扩散。这些扩散参数调节神经元信号、神经元-神经胶质细胞的通讯和突触外的“体积”传输。在神经元活动和病理状态期间，ECS体积分数显著减少，扩散屏障(曲折)增加。这些变化通常与细胞肿胀、细胞丢失、星形胶质细胞增生症、神经元和星形细胞突起的重排以及细胞外基质的变化有关。在发育、哺乳和衰老等生理状态下，它们也会发生变化。ECS体积的可塑性变化、曲折性和各向异性显著影响神经元-神经胶质细胞的通讯，神经胶质突起向突触、谷氨酸或GABA的溢出和突触串扰的空间关系。在许多病理状态下发生的组织扩散率的各种变化对诊断、药物输送和治疗具有重要意义。(C)2004年IBRO。爱思唯尔有限公司出版。保留所有权利。
Extrasynaptic communication between neurons or neurons and glia is mediated by the diffusion of neuroactive substances in the volume of the extracellular space (ECS). The size and irregular geometry of the diffusion channels in the ECS substantially differ not only around individual cells but also in different CNS regions and thus affect and direct the movement of various neuroactive substances in the ECS. Diffusion in the CNS is therefore not only inhomogeneous, but often also anisotropic. The diffusion parameters in adult mammals (including humans), ECS volume fraction alpha (alpha=ECS volume/total tissue volume) and tortuosity lambda (lambda(2) = free/apparent diffusion coefficient), are typically 0.20-0.25 and 1.5-1.6, respectively, and as such hinder the diffusion of neuroactive substances and water. These diffusion parameters modulate neuronal signaling, neuron-glia communication and extrasynaptic "volume" transmission. A significant decrease in ECS volume fraction and an increase in diffusion barriers (tortuosity) occur during neuronal activity and pathological states. The changes are often related to cell swelling, cell loss, astrogliosis, the rearrangement of neuronal and astrocytic processes and changes in the extracellular matrix. They are also altered during physiological states such as development, lactation and aging. Plastic changes in ECS volume, tortuosity and anisotropy significantly affect neuron-glia communication, the spatial relation of glial processes toward synapses, glutamate or GABA 'spillover' and synaptic crosstalk. The various changes in tissue diffusivity occurring during many pathological states are important for diagnosis, drug delivery and treatment. (C) 2004 IBRO. Published by Elsevier Ltd. All rights reserved.