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 micromol/min/kg protein). The capacity of GABA uptake into the platelets was higher in patients using valproate (0.66+/-0.09 micromol/min/kg protein), but not in those using ethosuximide (0.34+/-0.05 micromol/min/kg protein), when compared to controls (0.26+/-0.06 micromol/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.
Rainesalo
Sirpa
S
Brain Research Center, Medical School, University of Tampere, Tampere, Finland. sirpa.rainesalo@pshp.fi
Eriksson
Kai
K
Saransaari
Pirjo
P
Keränen
Tapani
T
D000612:4-Aminobutyrate Transaminase / Q000097:blood*; D000293:Adolescent; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004832:Epilepsy, Absence / Q000097:blood*; D005013:Ethosuximide / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D005680:gamma-Aminobutyric Acid / Q000097:blood*
D005680:gamma-Aminobutyric Acid; D005013:Ethosuximide; D000612:4-Aminobutyrate Transaminase