Beta-carbolines as tools in memory research: animal data and speculations.

Benzodiazepines induce in animals, as in humans, almost exclusively anterograde amnesia. The mechanism of this effect is still unsettled; however, explanations like state dependency which may be based on sedative or emotional properties of benzodiazepines are usually favoured in contrast to an interpretation in terms of true amnesia. It is proposed that by the use of beta-carbolines with agonist, partial agonist, antagonist and partial inverse agonist properties, the nature of the amnesia induced by benzodiazepine receptor agonists may be characterised. From a series of experiments it is concluded that the major reason for benzodiazepine-induced amnesia might be an impaired ability to filter interfering stimuli; that is, an attentional deficit. Since the antagonist beta-carbolines may play a key role in providing evidence as to the GABAergic involvement in cognitive processes, the pharmacological profile of ZK 93426 is presented. The results of the interaction of beta-carbolines with scopolamine will provide a basis on which to speculate on the GABAergic control of cholinergic neurotransmission and its therapeutic implications.