Glutamate uptake in blood platelets from epileptic patients.

Glutamate, the major excitatory amino acid neurotransmitter, is involved in epileptogenesis and initiation and spread of seizures. We studied glutamate uptake into blood platelets from patients with distinct epileptic syndromes: included were 20 patients with temporal lobe epilepsy and hippocampal sclerosis (TLE+HS), 20 with juvenile myoclonus epilepsy (JME) and 20 healthy volunteers matched for age and sex. The affinity of glutamate for the transporters was highest in patients with TLE+HS, but the maximal velocity of transport was highest in controls. There were no differences in the plasma levels of glutamate. Carbamazepine (CBZ), valproate (VPA) and lamotrigine (LTG) did not affect the uptake in vitro. The alterations observed in the uptake of glutamate in TLE+HS patients may reflect an up-regulated uptake of glutamate in the brain.