Abstract
Clonazepam was found to possess the strongest anticonvulsant activity against various seizures induced by electroshock, Metrazol, picrotoxin and strychnine among anti-epileptic drugs and other benzodiazepines as investigated in rats and mice. The anti-Metrazol activity of clonazepam was markedly higher than that against other types of experimental convulsions. Clonazepam suppressed EEG afterdischarges induced by stimulation of either dorsal hippocampus or amygdaloid complex of both freely moving rats and gallamineimmobilized cats. However, the drug had little effect on EEG afterdischarges following cerebral cortical stimulation in rats and on EEG arousal threshold in rats and cats. Further, the drug markedly inhibited evoked potentials of the ventral hippocampus after stimulation of ipsilateral basolateral amygdala, whereas the drug did not change the evoked potentials of the ventral hippocampus after stimulation of the contralateral structure. The drug markedly enhanced the dorsal root reflex and decreased synaptic recovery more than did other benzodiazepines but had no effect on post-tetanic potentiation in sp;nal cats. These results strongly suggest that the anti-convulsant activity of clonazepam is at least partly due to the inhibition of synaptic recovery and the enhancement of presynaptic inhibition.
