EFFECTS ON ANXIETY AND MEMORY OF SYSTEMIC AND INTRAAMYGDALA INJECTIONOF 5-HT3 RECEPTOR ANTAGONIST BRL 46470A

This study deals with the effects of the 5-HT3 receptor antagonist, BR L 46470A, on memory and anxiety, using the elevated T-maze. This metho d is useful for investigating the effects of anxiolytic drugs on memor y, and the relationships between neural subsystems involved in emotion ally related behaviors and in processes underlying learning. After the drug was either injected peripherally or microinjected into the amygd ala, the animals were tested on the elevated T-maze (30 or 15 min late r, respectively). Two kinds of aversively motivated behaviors, inhibit ory avoidance and one-way escape, were recorded. These behaviors may r eflect different types of fear/anxiety, namely, anticipatory anxiety a nd innate fear. Three days later, memory for these tasks was assessed by reexposing the subjects to the maze. The compound had an anxiolytic effect on the inhibitory avoidance response when given systemically, but an anxiogenic effect when injected into the amygdala. It had an an xiolytic action on the escape response when given either systemically or into the amygdala. The compound had no adverse effects on memory fo r either task. These results suggest that this new 5-HT3 antagonist ma y be useful in the treatment of certain types of anxiety disorders, es pecially those related to unconditioned fear, e.g. phobic or panic dis orders, with the likelihood of having no side effects on memory proces ses. The contrasting results obtained with different measures of anxie ty may also account for the inconsistencies found in the experimental literature dealing with compounds of this nature.