Differential seizure sensitivities to picrotoxinin in two inbred strains of mice (DBA/2J and BALB/c ByJ): parallel changes in GABA receptor-mediated chloride flux and receptor binding.
Two strains of mice were shown to possess a differential sensitivity to picrotoxinin-induced convulsions; picrotoxinin elicited both tonic and clonic seizures at lower doses in the DBA/2J (DBA) strain compared to the BALB/c ByJ (BALB) strain. Less protection of picrotoxinin-induced tonic seizures was afforded by pentobarbital in the DBA strain. Biochemical studies revealed that picrotoxin inhibited 36Cl- efflux from forebrain synaptoneurosomes only in the DBA strain. In addition, picrotoxin inhibited pentobarbital-induced 36Cl- efflux to a greater extent in the DBA strain. No differences were observed in the binding of [3H]muscimol or [35S]t-butylbicyclophosphorothionate (TBPS) to forebrain homogenates, while pentobarbital was a less potent inhibitor of [35S]TBPS binding in the DBA strain. These findings suggest a genetic basis for the behavioral differences in convulsant sensitivity as well as for the neurochemical differences in allosteric coupling between convulsant and depressant/anticonvulsant sites associated with the GABA receptor-gated Cl- channel.
Schwartz, RD; Seale, TW; Skolnick, P; Paul, SM
Volume / Issue
Start / End Page
International Standard Serial Number (ISSN)
Digital Object Identifier (DOI)