In vivo release of neuroactive amines and amino acids from the hippocampus of seizure-resistant and seizure-susceptible rats.
The in vivo release of six radiolabeled amino acids or amines in the hippocampus was investigated in genetically seizure-resistant and seizure-susceptible rats. No differences were found in the spontaneous or high K(+)-evoked efflux of ?-aminobutyric acid, norepinephrine or its metabolites, taurine or ?-aminoisobutyrate. However, seizure-susceptible rats released significantly more d-aspartic acid on K(+)-depolarization. The initial rate of release (flux) was also higher. In view of the ubiquity of synapses in the mammalian brain utilizing excitatory amino acids as their transmitter, we propose that an exaggerated release of these excitants might be a determinant of the innate seizure susceptibility in these animals.
Lehmann
A
A
Department of Pharmacology, University of Arizona Health Sciences Center, Tucson, AZ 85724, U.S.A.
Sandberg
M
M
Huxtable
R J
RJ