Pre- and post-training infusion of prazosin into the bed nucleus of the stria terminalis impaired acquisition and retention in a Morris water maze task

The bed nucleus of the stria terminalis (BNST) is interconnected with the amygdala that is implicated in memory modulation. In view of the innervation of this structure by the hippocampus and brain stem noradrenergic nuclei, this study examined the role of BNST noradrenergic activity in acquisition, formation and expression of spatial memory. Male Wistar rats with indwelling cannulae in the BNST were trained on a spatial navigation task in the Morris water maze. Groups of rats received intra-BNST infusion of vehicle, norepinephrine, prazosin or both drugs shortly before or after each daily training session, or shortly before retention tests. Results showed that pre- or posttraining infusion of 1.0 μg prazosin impaired acquisition and retention, but the treatment had no effect on a cued response task. Posttraining infusion of 1.0 μg norepinephrine enhanced acquisition and retention, and this enhancing effect was blocked by simultaneous infusion of 0.3 μg prazosin. Pretest intra-BNST of prazosin or norepinephrine at a dose of 1.0 μg did not impair expression of the spatial navigation memory. These findings suggest that the BNST noradrengergic function is involved in modulating acquisition and formation of spatial memory that engage the hippocampus.