Comparison between the effects of the benzodiazepine receptor ligands methyl beta-carboline-3-carboxylate and diazepam in two learning situations in mice

Benzodiazepines are known to induce profound amnesia in man. In this report, we show, in mice, that whereas benzodiazepine diazepam indeed impairs performance, methyl beta-carboline-3-carboxylate gB-CCM), an inverse agonist of the benzodiazepine receptor, on the contrary enhances performance. The two learning situations used were one-trial passive avoidance and multiple-trial light-dark discrimination in a T-maze. Since these effects are blocked by Ro 15–1788, a specific antagonist of the benzodiazepine receptor, they are likely to be mediated by the benzodiazepine receptor. They seem to involve action on learning rather than on memory.