The dose response curves of picrotoxin-induced seizures and pentylenetetrazol-induced seizures were shifted to the right by the benzodiazepine (BZ) receptor agonist lorazepam, and to the left by the inverse agonists, DMCM, ZK 90886, FG 7142 and CGS 8216. The BZ receptor antagonists ZK 93426 and Ro 15-1788 had no effect on the dose response curves. The anticonvulsive action of lorazepam and the proconvulsive action of DMCM against picrotoxin-induced seizures and against pentylenetetrazol-induced seizures was inhibited by low doses of ZK 93426 and Ro 15-1788. These results indicate that the bidirectional effects of benzodiazepine receptor ligands on picrotoxin and pentylenetetrazol induced seizures is actually mediated through benzodiazepine receptors.
