Comparisons between patterns of convulsions induced by two beta-carbolines in 10 inbred strains of mice.

The beta-carbolines, methyl-beta-carboline-3-carboxylate (beta-CCM) and 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM) are known to have pharmacological properties opposite to those of agonistic benzodiazepines. Convulsions induced by these drugs lead to differential patterns, such as clonus, myoclonic or tonic seizures. In 10 different inbred strains of mice we investigated whether the responsiveness to the two drugs was the same, irrespective of the pattern of convulsions. We found the same ranking in the responsiveness of the strains to both drugs in the case of myoclonic seizures. No such correlation could be found for clonus or tonic seizures. Our conclusion is that the same genetic factors determine myoclonic seizures, whereas a plurality of mechanisms underly the other patterns. Thus, myoclonic seizures seem to be the most appropriate index for evaluating the convulsant action of beta-carbolines in genetic experiments.