Is the muscle relaxant effect of diazepam in spastic mutant rats mediated through GABA-independent benzodiazepine receptors?

Diazepam (0.4-0.8 mg/kg i.p.) reduced the spontaneous activity in the electromyogram (EMG) recorded from the gastrocnemius-soleus muscle of spastic mutant Han--Wistar rats in a dose-dependent manner. The depressant effect of diazepam (0.8 mg/kg) on the EMG activity was antagonized by Ro 15-1788 (5 mg/kg i.p.) and by picrotoxin (2 mg/kg i.p.), but not by bicuculline (2 mg/kg i.p.). These results suggest that diazepam depresses EMG activity of mutant rats by mechanisms related to the interaction of the drug with GABA-independent benzodiazepine receptors.