Midazolam administered into the amygdala impairs retention of an inhibitory avoidance task.

This experiment investigated the amnestic effects of injections of the benzodiazepine midazolam administered into the amygdala prior to training on an inhibitory avoidance task. Male Sprague-Dawley rats were implanted bilaterally with cannulae aimed at the amygdala. After 1 week recovery a buffer solution or midazolam (3 or 10 micrograms/0.5 microliters) was injected bilaterally 5 min before a single training trail in a two-compartment inhibitory avoidance apparatus. The pretraining intra-amygdala injections of midazolam did not affect the training step-through latencies. However, on a 48-h retention test the step-through latencies of the midazolam-treated animals were significantly lower than those of the buffer controls. These findings are consistent with other recent evidence indicating that the amygdala is involved in mediating the amnestic effects of benzodiazepines.