Convulsions induced by submaximal dose of pentylenetetrazol in mice are antagonized by the benzodiazepine antagonist Ro 15-1788

The effects of benzodiazepine antagonist Ro 15–1788, alone or with diazepam, were studied in mice on convulsions induced by pentylenetetrazol (PTZ). We found that Ro 15–1788 (1 mg/kg) was able to antagonize the anticonvulsive effects of diazepam (1 mg/kg), but also had, with submaximal doses of PTZ (65 mg/kg), its own anti-convulsive action. At very low doses (0.1 mg/kg), it even potentiated the anticonvulsive effects of diazepam (0.05 mg/kg). This dual action provides evidence for partial agonist properties of the antagonist Ro 15–1788.