INCREASE OF GLUCOSE-TRANSPORTER DENSITIES (GLUT1 AND GLUT3) DURING CHRONIC ADMINISTRATION OF NICOTINE IN RAT-BRAIN

Chronic infusion of nicotine is known to result in a distinct pattern of increases in local cerebral glucose utilization (LCGU). The present study addresses the question whether this increase in LCGU is paralle led by (1) a local increase in Glut1 and/or Glut3 glucose transporter densities and (2) a local increase in capillary density in the brain. Nicotine was infused by osmotic minipumps for one week. In cryosection s of rat brains local densities of Glut1 (vascular) and 61ut3 (neurona l) glucose transporters were measured by immunoautoradiographic method s whereas local capillary densities were determined by an immunofluore scent method. Densities of glucose transporters Glut1 and Glut3 were i ncreased in 12 of the 27 structures investigated. Glut1 was elevated i n four additional structures and Glut3 in two more structures. Compari son of the changes in transporter densities with the changes of LCGU m easured In a previous study during chronic nicotine infusion showed th at LCGU was also elevated in most of these structures. In contrast, ca pillary density remained unchanged in all structures investigated. It is concluded that one week of nicotine infusion is sufficient to raise the densities of Glut1 and Glut3 glucose transporters predominantly i n those structures in which LCGU is elevated. The unchanged capillary density under these conditions indicates an increased density of Glut1 transporters per capillary. (C) 1998 Elsevier Science B.V.