Decreased cortical levels of astrocytic glutamate transport protein GLT-1 in a rat model of posttraumatic epilepsy

The extracellular homeostasis of glutamate in the brain is maintained by th e efficient uptake into astroglial cells. The high extracellular glutamate levels seen during seizures are therefore probably a result of both an incr eased synaptic release and a deranged glutamate uptake. In this study we us ed immuno-blotting technique to measure the cortical levels of the astrocyt ic glutamate transport protein (GLT-1) and of the glutamate and aspartate t ransporting protein (GLAST) in an epilepsy model induced by ferrous chlorid e injection in the cortex of rats. The levels of GLT-1 were lower in epilep tic rats than in controls, day 1 and 5 after induction, but not at 3 months . Glial fibrillary protein (GFAP) levels increased with time in the epilept ic model, whereas GLAST and beta-tubulin III remained unchanged compared to controls. The results suggest that the transient decrease of GLT-1 could p lay a role in epileptogenesis, while recurrent seizure activity may be main tained by other mechanisms. (C) 2000 Elsevier Science Ireland Ltd. All righ ts reserved.