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

The effects of intra-amygdala injection of midazolam (20 nmol) and 8-hydrox y-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. T his test allows the measurement, in the same rat, of conditioned and uncond itioned fear/anxiety responses. Both drugs impaired inhibitory avoidance of the open arms of the T-maze (task representing conditioned fear), indicati ng an anxiolytic effect, but did not change escape performance from one of the open arms (representing unconditioned fear). The results further implic ate gamma-aminoibutyric acid (GABA)/benzodiazepine and serotonergic systems within the basolateral/lateral amygdala in the modulation of conditioned a nxiety responses. (C) 1999 Elsevier Science B.V. All rights reserved.