Diffusion barriers evoked in the rat cortex by reactive astrogliosis
Diffusion barriers evoked in the rat cortex by reactive astrogliosis
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DOI：
10.1002/(sici)1098-1136(199910)28:1
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发表时间：
1999-10
期刊：
影响因子：
6.2
通讯作者：
T. Roitbak;E. Sykova
中科院分区：
文献类型：
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作者：
T. Roitbak;E. Sykova
使用四甲基铵（TMA+）选择性微电极，根据TMA+的浓度-时间曲线确定单侧皮质刺伤周围星形胶质细胞组织细胞外间隙（ECS）扩散参数的变化。在伤后3、7、21和35天（dpw）测定损伤同侧和对侧大脑半球的三个扩散参数-ECS体积分数α（α = ECS体积/总组织体积）、迂曲度λ（λ2 = D/ADC;其中D是游离TMA+在脑中的表观扩散系数，ADC是TMA+在脑中的表观扩散系数）和非特异性TMA+摄取k′-。扩散实验后，对组织切片进行胶质细胞酸性蛋白（GFAP）和硫酸软骨素蛋白聚糖（CSPG）免疫染色。在伤口周围300-1000 μm的区域，α在3、7和21 dpw时增加约20%，但在35 dpw时恢复至对照值; λ在所有四个时间段均增加，在7 dpw时达到最大值。在7、21和35 dpw时，k′低于对侧半球。从伤口1，500 - 2，000 μm处进行的测量显示，λ仅在7 dpw处增加。ECS扩散参数变化的时间过程与GFAP和CSPG染色增加密切相关。我们的研究结果表明，星形胶质细胞增生显着改变了神经组织的扩散特性，使其不那么宽容。肥大的星形胶质细胞过程和一些细胞外基质分子的增强形成都可以通过ECS中分子扩散的变化影响神经元-胶质细胞通信、突触之间的“串扰”、突触外传递和再生过程。GLIA 28：40-48，1999.© 1999 Wiley利斯公司
Changes in extracellular space (ECS) diffusion parameters in astrogliotic tissue around a unilateral cortical stab wound were determined from concentration‐time profiles of tetramethylammonium (TMA+) using TMA+‐selective microelectrodes. Three diffusion parameters—ECS volume fraction α (α = ECS volume/ total tissue volume), tortuosity λ (λ2 = D/ADC; where D is the free and ADC is the apparent diffusion coefficient of TMA+ in the brain), and nonspecific TMA+uptake k′—were determined at 3, 7, 21, and 35 days postwounding (dpw), in the hemispheres ipsilateral and contralateral to the lesion. Following diffusion experiments, tissue sections were immunostained for glial fibrillary acidic protein (GFAP) and chondroitin‐sulphate proteoglycans (CSPG). In the area 300–1000 μm around the wound, α was increased at 3, 7, and 21 dpw by about 20% but returned to control values at 35 dpw; λ was increased at all four intervals, reaching a maximum at 7 dpw. k′ was lower than in the contralateral hemisphere at 7, 21, and 35 dpw. Measurements 1,500–2,000 μm from the wound revealed only an increase in λ at 7 dpw. The time course of changes in ECS diffusion parameters closely correlated with increased staining for GFAP and CSPG. Our results show that astrogliosis significantly changes the diffusion properties of nervous tissue, making it less permissive. Both hypertrophied astrocytic processes and an enhanced formation of some extracellular matrix molecules could affect, through changes in the diffusion of molecules in the ECS, neuron–glia communication, “cross‐talk” between synapses, extrasynaptic transmission, and regenerative processes. GLIA 28:40–48, 1999. © 1999 Wiley‐Liss, Inc.