Department of Pediatrics I, University Medical Center Göttingen, Göttingen, Germany.
Br J Pharmacol. 2013 Aug;169(7):1561-73. doi: 10.1111/bph.12218.
The blood-brain barrier (BBB) restricts drug penetration to the brain preventing effective treatment of patients suffering from brain tumours. Intra-arterial injection of short-chain alkylglycerols (AGs) opens the BBB and increases delivery of molecules to rodent brain parenchyma in vivo. The mechanism underlying AG-mediated modification of BBB permeability is still unknown. Here, we have tested the effects of AGs on barrier properties of cultured brain microvascular endothelial cells.
The effects of two AGs, 1-O-pentylglycerol and 2-O-hexyldiglycerol were examined using an in vitro BBB model consisting of primary cultures of rat brain endothelial cells, co-cultured with rat cerebral glial cells. Integrity of the paracellular, tight junction-based, permeation route was analysed by functional assays, immunostaining for junctional proteins, freeze-fracture electron microscopy, and analysis of claudin-claudin trans-interactions.
AG treatment (5 min) reversibly reduced transendothelial electrical resistance and increased BBB permeability for fluorescein accompanied by changes in cell morphology and immunostaining for claudin-5 and β-catenin. These short-term changes were not accompanied by alterations of inter-endothelial tight junction strand complexity or the trans-interaction of claudin-5.
AG-mediated increase in brain endothelial paracellular permeability was short, reversible and did not affect tight junction strand complexity. Redistribution of junctional proteins and alterations in the cell shape indicate the involvement of the cytoskeleton in the action of AGs. These data confirm the results from in vivo studies in rodents characterizing AGs as adjuvants that transiently open the BBB.
血脑屏障（BBB）限制了药物向大脑的渗透，从而无法有效治疗脑肿瘤患者。短链烷基甘油（AGs）的动脉内注射可以打开 BBB，并增加体内向啮齿动物脑实质输送分子的数量。AG 介导的 BBB 通透性改变的机制尚不清楚。在这里，我们测试了 AGs 对培养的脑微血管内皮细胞的屏障特性的影响。
使用由大鼠脑内皮细胞原代培养物与大鼠脑胶质细胞共培养组成的体外 BBB 模型，检测了两种 AG（1-O-戊基甘油和 2-O-己基二甘油）的作用。通过功能测定、紧密连接蛋白的免疫染色、冷冻断裂电子显微镜和 Claudin-C Claudin 跨相互作用分析，分析了细胞旁、基于紧密连接的渗透途径的完整性。
AG 处理（5 分钟）可逆地降低了跨内皮电阻，增加了荧光素的 BBB 通透性，同时伴有细胞形态和 Claudin-5 和 β-连环蛋白免疫染色的变化。这些短期变化不伴有内皮细胞之间紧密连接链复杂性或 Claudin-5 跨相互作用的改变。
AG 介导的脑内皮细胞旁通透性增加是短暂的、可逆的，不会影响紧密连接链的复杂性。连接蛋白的重新分布和细胞形状的改变表明细胞骨架参与了 AG 的作用。这些数据证实了在啮齿动物体内研究的结果，将 AG 描述为短暂打开 BBB 的佐剂。
