MacDonald P N, Bok D, Ong D E
Department of Biochemistry, Vanderbilt University, Nashville, TN 37232.
Proc Natl Acad Sci U S A. 1990 Jun;87(11):4265-9. doi: 10.1073/pnas.87.11.4265.
Brain is not generally recognized as an organ that requires vitamin A, perhaps because no obvious histologic lesions have been observed in severely vitamin A-deficient animals. However, brain tissue does contain cellular vitamin A-binding proteins and a nuclear receptor protein for retinoic acid. In the present study, immunohistochemical techniques were used to determine the cell-specific location of cellular retinol-binding protein in human and rat brain tissue. Cellular retinol-binding protein was localized specifically within the endothelial cells of the brain microvasculature and within the cuboidal epithelial cells of the choroid plexus, two primary sites of the mammalian blood-brain barrier. In addition, autoradiographic procedures demonstrated binding sites for serum retinol-binding protein in the choroidal epithelium. These observations suggest that a significant movement of retinol across the blood-brain barrier may occur.
大脑通常不被认为是一个需要维生素A的器官，这可能是因为在严重缺乏维生素A的动物中未观察到明显的组织学病变。然而，脑组织确实含有细胞视黄醇结合蛋白和视黄酸的核受体蛋白。在本研究中，采用免疫组织化学技术来确定细胞视黄醇结合蛋白在人和大鼠脑组织中的细胞特异性定位。细胞视黄醇结合蛋白特异性定位于脑微血管的内皮细胞以及脉络丛的立方上皮细胞内，这是哺乳动物血脑屏障的两个主要部位。此外，放射自显影程序显示脉络膜上皮中有血清视黄醇结合蛋白的结合位点。这些观察结果表明视黄醇可能会大量穿过血脑屏障。
