Anxiolytic effect of intra-amygdala injection of midazolam and 8-hydroxy-2-(di- n-propylamino)tetralin in the elevated T-maze

Abstract

The effects of intra-amygdala injection of midazolam (20 nmol) and 8-hydroxy-2-(di- n-propylamino)tetralin (8-OH-DPAT; 8 and 16 nmol) were investigated in rats submitted to the elevated T-maze, a new animal model of anxiety. This test allows the measurement, in the same rat, of conditioned and unconditioned fear/anxiety responses. Both drugs impaired inhibitory avoidance of the open arms of the T-maze (task representing conditioned fear), indicating an anxiolytic effect, but did not change escape performance from one of the open arms (representing unconditioned fear). The results further implicate γ-aminobutyric acid (GABA)/benzodiazepine and serotonergic systems within the basolateral/lateral amygdala in the modulation of conditioned anxiety responses.