Uptake of GABA and Activity of GABA Transaminase in Blood Platelets from Children with Absence Epilepsy

Childhood absence epilepsy (CAE) is a well-defined generalized epilepsy syndrome clinically characterized by frequent absence seizures. The aim of this study was to assess the activity of GABA transaminase (GABA-T) and the kinetic parameters of GABA uptake in platelets from patients with CAE. We studied 13 patients with CAE and eight sex- and age-matched controls. The mean activity of GABA-T was lower in patients with CAE than in controls (1.22 ± 0.05 vs. 1.75 ± 0.10 μmol/min/kg protein). The capacity of GABA uptake into the platelets was higher in patients using valproate (0.66 ± 0.09 μmol/ min/kg protein), but not in those using ethosuximide (0.34 ± 0.05 μmol/min/kg protein), when compared to controls (0.26 ± 0.06 μmol/min/kg protein). The affinity of the transporters was not altered. The observed peripheral alterations may indicate impaired function of brain GABAergic systems in children with absence epilepsy.