Post-training systemic and intra-amygdala administration of the GABA-B agonist baclofen impairs retention.

The effects of the GABA-B receptor agonist baclofen on memory storage were studied in two series of experiments. In the first series, CD-1 mice were trained in two aversively motivated tasks: a one-trial inhibitory avoidance task and a classical conditioning task (conditional emotional response). Immediate post-training ip administration of (+/-)baclofen (10 and 30 mg/kg) impaired retention of animals in both tasks. The effect was time-dependent: Retention was not affected by baclofen administered 120 min after training. In the second series of experiments, which used Sprague-Dawley rats, post-training intra-amygdala administration of baclofen impaired retention of an inhibitory avoidance response. These results support the view that the GABAergic system is involved in the modulation of memory storage and that the amygdaloid complex may be a critical site for effects of drugs affecting the GABAergic system.