Quisqualate-preferring glutamate receptors were determined in membranes from frontal cortex, occipital cortex, hippocampus and cerebellum, from seizure-prone DBA/2J BOM and seizure-resistant C57/BL mice. The animals were studied 21, 27 and 40 days postnatally, i.e., before, during and after the age at which DBA mice are most susceptible to seizures. Radio-binding assays were performed using [3H]AMPA in the presence of 100 nM glutamate. Except for the occipital cortex, where no significant differences between the two strains were observed, all areas of the brain of DBA mice exhibited significantly (P less than 0.001, t test) higher AMPA binding than the corresponding areas of C57/BL mice at 27 days of age. At pre- and post-susceptible ages, the two strains showed no significant differences in the hippocampus and occipital cortex. A significant difference was observed, however, in the frontal cortex and cerebellum at the ages of 21 and 40 days, respectively, although this difference was considerably less than at 27 days. In addition to determination of glutamate receptors, GABA-receptor binding was also studied in membranes from the same cerebral areas and at the above-mentioned ages. Binding characteristics, using [3H]GABA as the ligand, were essentially identical in the two strains at all ages investigated, i.e., both low and high affinity GABA receptors could be identified with KD values of 6-16 nM and 100-800 nM, respectively.