A SINGLE GLUCOSE-TRANSPORTER CONFIGURATION IN NORMAL PRIMATE BRAIN ENDOTHELIUM - COMPARISON WITH RESECTED HUMAN BRAIN

Cellular distribution of the Glut1 glucose transporter in normal prima te brains was analyzed by immunogold electron microscopy. Two configur ations of endothelial Glut1 glucose transporter (high and low density capillaries) have been found in resections of traumatically injured an d epileptogenic human brain; the objective of the present study was to ascertain whether these same 2 capillary populations, expressing high and low glucose transporter densities, were the common configuration in normal brain. The relative numbers of Glut1 glucose transporter-ass ociated gold particles on luminal and abluminal endothelial cell membr anes were determined within the cerebral cortex of several normal, non human primates. Low Glut1 densities were seen in brain endothelia of b oth the rhesus and squirrel monkey cortex, with slightly greater quant ities of Glut1 in vervet monkey cortices. The Glut1 transporter was mo st highly expressed in the baboon cortex, approaching the concentratio ns seen in human brains. In the rhesus, squirrel, and vervet monkeys, Glut1 concentrations were greater on the abluminal than luminal capill ary membranes. In contrast, mean luminal membrane Glut1 concentrations were greater in baboons, resembling the distribution seen in the huma n brain. Brain regional differences in transporter concentration were seen in comparing membrane densities in the baboon cortex (similar to 15 Glut1-gold particles per mu meter), hippocampus (similar to 12 Glut 1 gold particles per mu meter), cerebellum (similar to 6 Glut1-gold pa rticles per mu meter), and retinal microvasculature (similar to 20 Glu t1-gold particles per mu meter). We conclude that a single, uniform Gl ut1 distribution characterizes brain capillaries of normal nonhuman pr imates, and hypothesize that the presence of high and low density gluc ose transporter endothelial cells (seen in human traumatic injury and seizure resections) represents a pathologic response to brain insult.