EXPRESSION OF THE NA-D-GLUCOSE COTRANSPORTER SGLT1 IN NEURONS()

In brains of the rabbit, pig, and human, expression of the high-affini ty Na+-D-glucose cotransporter SGLT1 and of the protein RS1, which alt ers the activity of SGLT1, was demonstrated. In situ hybridization sho wed that SGLT1 and RSI are transcribed in pyramidal cells of brain cor tex and hippocampus and in Purkinje cells of cerebellum. In neurons of pig brain SGLT1 protein was demonstrated by western blotting with syn aptosomal membranes and by immunohistochemistry, which showed SGLT1 in pyramidal and Purkinje cells. To test whether SGLT1 in neurons may be activated during increased D-glucose consumption, an epileptic seizur e was induced in rat brain, and the uptake of specific nonmetabolized substrates of SGLT1 {[C-14] methyl-alpha-D-glucopyranoside ([C-14]AMG) } and of Na+-independent transporters {2-deoxy-D-[C-14] glucose ([C-14 ]2-DG)} was analyzed by autoradiography. During the seizure the uptake of AMG and 2-DG was increased in the focus. Within two hours after th e seizure 2-DG uptake in the focus returned to normal. In contrast, th e AMG uptake in the focus area was still increased 1 day later. The da ta show that the high-affinity Na+-D-glucose cotransporter SGLT1 is ex pressed in neurons and can be up-regulated.