Immunological analysis of glucose transporters expressed in different regions of the rat brain and central nervous system.

Glucose is the major energy source for brain tissue. It is now well established that glucose crosses the blood-brain barrier by facilitated diffusion mediated by the erythrocyte-type (GLUT 1) glucose transporter. Northern blot analysis has indicated that brain tissue expresses two different glucose transporters, the erythrocyte-type transporter and the brain-type transporter (GLUT 3). Here we use a panel of antibodies specific for four glucose transporters to examine the distribution of these transporters in various regions of rat brain and central nervous system. We show that GLUT 1 and GLUT 3 are expressed in virtually all regions of the brain examined, but that the relative levels of the proteins differ. We also demonstrate that GLUT 2 appears to be widely expressed in all brain regions, but at apparently low levels. In addition, GLUT 4 is expressed in the pituitary, the hypothalamus and the medulla. These results are discussed in the light of potential glucose-regulated processes in the brain.