Orte C, Lawrenson J G, Finn T M, Reid A R, Allt G
Reta Lila Weston Institute of Neurological Studies, University College London Medical School, UK.
Anat Embryol (Berl). 1999 Jun;199(6):509-17. doi: 10.1007/s004290050248.
A number of major properties of endothelial cells (EC) at the blood-brain barrier (BBB) have been shown to be astrocyte-dependent. Whether analogous properties at the blood-nerve barrier (BNB) are induced and maintained by Schwann cells has not been investigated. As a preliminary investigation we have undertaken a comparative study of six EC membrane markers at the BBB and BNB and perineurium. Employing immunoblotting and immunocytochemistry the relative distribution between rat brain cortex and sciatic nerve was determined for the glucose transporter (GLUT-1), the transferin receptor (OX-26), the endothelial barrier antigen (EBA) and the OX-47 antigen. Using enzyme cytochemistry the same comparison was made for gamma-glutamyl transpeptidase (GGTP) and alkaline phosphatase. By immunocytochemistry GLUT-1 was uniformly strongly represented in brain EC, nerve EC and perineurium. OX-26 was strongly positive in brain EC but present only in trace quantities in nerve EC and perineurium. EBA similarly showed strong positivity in brain EC and trace amounts in nerve EC but was absent from perineurium. OX-47 was present moderately in brain EC and perineurium but absent from nerve EC. Quantitative immunoblotting of brain and sciatic nerve homogenates showed statistically significant differences in the level of expression of EBA and OX-26 between the two tissues. Enzyme cytochemistry showed that GGTP was strongly positive in brain EC but absent from nerve EC and perineurium. Alkaline phosphatase stained strongly in brain and nerve EC and was absent from perineurium. In summary the six membrane markers were heterogeneously represented in nerve compared with brain. This pattern of distribution in the nerve cannot simply be accounted for by the absence of astrocytes and their inductive influences. Any inductive influences of Schwann cells require investigation.
血脑屏障（BBB）处内皮细胞（EC）的许多主要特性已被证明依赖于星形胶质细胞。血神经屏障（BNB）处的类似特性是否由施万细胞诱导并维持尚未得到研究。作为一项初步研究，我们对BBB、BNB和神经束膜处的六种EC膜标记物进行了比较研究。采用免疫印迹和免疫细胞化学方法，测定了大鼠脑皮质和坐骨神经中葡萄糖转运蛋白（GLUT-1）、转铁蛋白受体（OX-26）、内皮屏障抗原（EBA）和OX-47抗原的相对分布。使用酶细胞化学方法对γ-谷氨酰转肽酶（GGTP）和碱性磷酸酶进行了同样的比较。通过免疫细胞化学方法，GLUT-1在脑EC、神经EC和神经束膜中均有均匀较强的表达。OX-26在脑EC中呈强阳性，但在神经EC和神经束膜中仅微量存在。EBA同样在脑EC中呈强阳性，在神经EC中微量存在，但在神经束膜中不存在。OX-47在脑EC和神经束膜中中度存在，但在神经EC中不存在。对脑和坐骨神经匀浆的定量免疫印迹显示，两种组织之间EBA和OX-26的表达水平存在统计学显著差异。酶细胞化学显示，GGTP在脑EC中呈强阳性，但在神经EC和神经束膜中不存在。碱性磷酸酶在脑和神经EC中染色强烈，在神经束膜中不存在。总之，与脑相比，这六种膜标记物在神经中的表达具有异质性。神经中的这种分布模式不能简单地用星形胶质细胞的缺失及其诱导影响来解释。施万细胞的任何诱导影响都需要进行研究。
