The AMPA/kainate receptor antagonist, LY 300164, increases the anticonvulsant effects of diazepam

The aim of this study was to evaluate the influence of 7-acetyl-5-(4-aminophenyl)-8,9-dihydro-8-methyl-7H-1,3-dioxolo(4,5H)-2,3-benzodiazepine (LY 300164), a selective non-competitive antagonist at α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)/kainate receptors, on the protection provided by diazepam against electrically- and chemically-evoked seizures in rodents. LY 300164 (2 mg/kg) was devoid of any significant action upon each seizure parameter in kindled rats (seizure severity, seizure duration, after-discharge duration). LY 300164 (5 mg/kg) exerted a significant anticonvulsive effect as regards seizure and after-discharge durations. Combined treatment with LY 300164 (2 mg/kg) and diazepam (0.3125–1.25 mg/kg) resulted in the clear-cut anticonvulsive activity. It is noteworthy that the antiseizure potency of the combined treatment (diazepam 1.25 mg/kg plus LY 300164 2 mg/kg) was comparable to that of diazepam (10–20 mg/kg) alone. The combination of diazepam (1.25 mg/kg) with LY 300164 (2 mg/kg) did not induce any significant motor impairment in the rotorod test or memory deficit in the passive-avoidance task. In contrast, diazepam alone (10–20 mg/kg) had pronounced adverse effects in kindled animals.