Deficit in long-term contextual fear memory induced by blockade of beta-adrenoceptors in hippocampal CA1 region.

The present study investigated the effects of intra-CA1 infusion of d,l-propranolol, the beta-adrenergic antagonist, on memory for contextual fear conditioning. d,l-Propranolol administered 5 min ('0 h') postconditioning impaired long-term but not short-term contextual fear memory, while it was ineffective when administered 6 h postconditioning, suggesting that there is a time window for beta-adrenoceptors to play a role. Thus, we conclude that beta-adrenoceptors in area CA1 are involved in regulating consolidation of contextual fear memory, with '0 h' but not 6 h post-training, a sensitive time point for the beta-adrenergic involvement.