Absence of amnestic effect of an anxiolytic 5-HT3 antagonist (BRL 46470A) injected into basolateral amygdala, as opposed to diazepam.

This experiment compares the effects of microinjections into the basolateral amygdala nucleus of diazepam (DZP) and a new 5-HT3 receptor antagonist, BRL 46470A, on acquisition and retention of an inhibitory avoidance tasks by rats. The animals were microinjected with DZP or BRL 46470A between 10 and 15 min before the learning trial. Retention testing 48 h later showed impaired retention in animals injected with DZP but not with BRL 46470A. These results show that BRL 46470A, a compound suggested to have anxiolytic effects does not induce amnesia. This evidence for a possible dissociation between anxiety-reducing and memory-disrupting effects of a drug has implications, for one, for the understanding of the neuronal substrates mediating these effects, and secondly, for the search for anxiolytic agents devoid of undesirable side effects on memory processes.