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 the efficient uptake into astroglial cells. The high extracellular glutamate levels seen during seizures are therefore probably a result of both an increased synaptic release and a deranged glutamate uptake. In this study we used immuno-blotting technique to measure the cortical levels of the astrocytic glutamate transport protein (GLT-1) and of the glutamate and aspartate transporting protein (GLAST) in an epilepsy model induced by ferrous chloride injection in the cortex of rats. The levels of GLT-1 were lower in epileptic 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 epileptic model, whereas GLAST and beta-tubulin III remained unchanged compared to controls. The results suggest that the transient decrease of GLT-1 could play a role in epileptogenesis, while recurrent seizure activity may be maintained by other mechanisms.