Leino R L, Gerhart D Z, Drewes L R
Department of Anatomy and Cell Biology, School of Medicine, University of Minnesota, Duluth, MN 55812, USA.
Brain Res Dev Brain Res. 1999 Mar 12;113(1-2):47-54. doi: 10.1016/s0165-3806(98)00188-6.
Transcellular transport of energy substrates across the vascular endothelial cells of the brain is accomplished by integral membrane carrier proteins, such as the glucose transporter GLUT1 and the monocarboxylic acid transporter MCT1. The abundance of these proteins may vary depending on age and nutritional status. In this study we compared the expression of MCT1 in cerebral cortex of suckling and adult rats to determine whether the former, which use considerably more monocarboxylates such as lactate and ketone bodies as fuel than do older rats, correspondingly express more MCT1 than adults. Using electron microscopic immunogold methods, we found that 17-day old suckling rat pups had 25 times more MCT1 labeling in the membranes of capillary endothelial cells than adults. This transporter was nearly equally distributed in luminal and abluminal membranes with less than 10% of the immunogold particles in the endothelial cytoplasmic compartment. The suckling rats also had 15 times more immunogold particles associated with pericyte membranes and 19 times heavier labeling of membranes associated with astrocytic end feet adjacent to microvessels. Neuropil and choroid plexus were lightly labeled. Some MCT1-positive astrocyte and neuron cell bodies were observed, suggesting active synthesis of MCT1 by these cells. The potential for regulation of expression of MCTs by dietary or other factors may have important consequences for the progression and treatment of cerebrovascular disorders and other diseases.
能量底物跨脑微血管内皮细胞的跨细胞转运是由整合膜载体蛋白完成的，如葡萄糖转运蛋白GLUT1和单羧酸转运蛋白MCT1。这些蛋白的丰度可能因年龄和营养状况而异。在本研究中，我们比较了乳鼠和成年大鼠大脑皮层中MCT1的表达，以确定前者（与成年大鼠相比，前者使用更多的单羧酸盐如乳酸和酮体作为燃料）是否相应地比成年大鼠表达更多的MCT1。使用电子显微镜免疫金方法，我们发现17日龄的乳鼠幼崽毛细血管内皮细胞膜上的MCT1标记比成年大鼠多25倍。这种转运蛋白在管腔膜和管腔外膜中的分布几乎相等，在内皮细胞质区室中的免疫金颗粒不到10%。乳鼠与周细胞膜相关的免疫金颗粒也多15倍，与微血管相邻的星形胶质细胞终足相关膜的标记重19倍。神经毡和脉络丛标记较轻。观察到一些MCT1阳性星形胶质细胞和神经元细胞体，表明这些细胞可活跃合成MCT1。饮食或其他因素对MCTs表达的调节潜力可能对脑血管疾病和其他疾病的进展及治疗产生重要影响。
