Lawrenson J G, Reid A R, Finn T M, Orte C, Allt G
Reta Lila Weston Institute of Neurological Studies, University College London Medical School, UK.
Anat Embryol (Berl). 1999 Jan;199(1):29-34. doi: 10.1007/s004290050206.
Pial microvessels have several important blood-brain barrier (BBB) characteristics in common with cerebral microvessels, despite lacking their astrocytic ensheathment. We have therefore determined whether they have the same distribution of two enzymes, gamma-glutamyl transpeptidase (GGTP) and alkaline phosphatase, both of which are known to be astrocyte-dependent. GGTP was absent from all rat pial microvessels but strongly present in brain cortical capillaries. Alkaline phosphatase was heterogeneously expressed in pial microvessels, including capillaries, but strongly positive in brain cortical capillaries. Diffusible, inductive factors produced by astrocytes could account for these differences in enzyme distribution between the two vessel types. Furthermore, differences in expression between the two markers may reflect their differing sensitivities to the astrocytic factors. Caution is urged in the common usage of the pial microvessel as a model system in BBB studies.
软脑膜微血管尽管缺乏星形胶质细胞的包绕，但仍具有一些与脑微血管相同的重要血脑屏障（BBB）特征。因此，我们确定了它们是否具有两种酶，即γ-谷氨酰转肽酶（GGTP）和碱性磷酸酶的相同分布，这两种酶都已知依赖于星形胶质细胞。所有大鼠软脑膜微血管均未检测到GGTP，但在脑皮质毛细血管中大量存在。碱性磷酸酶在软脑膜微血管（包括毛细血管）中呈异质性表达，但在脑皮质毛细血管中呈强阳性。星形胶质细胞产生的可扩散诱导因子可能解释了这两种血管类型之间酶分布的差异。此外，两种标志物表达的差异可能反映了它们对星形胶质细胞因子的不同敏感性。在血脑屏障研究中，将软脑膜微血管作为模型系统普遍使用时应谨慎。
