Retrieval of spatial information in Nijmegen high and low responders: involvement of beta-adrenergic mechanisms in the nucleus accumbens.

Rats selected on the basis of their apomorphine susceptibility or on the basis of their response to novelty were used to investigate the role of mesolimbic adrenoceptors in the retrieval of spatial information in the water maze task. Apomorphine-susceptible rats and high responders to novelty (HR) showed a relatively bad retrieval during the 1st trial of the 2nd day compared with apomorphine-unsusceptible rats and low responders to novelty (LR). Intra-accumbens injections of different doses of the beta-agonist isoproterenol, given just before that trial, disrupted the retrieval in LR rats but not in HR rats. The beta-antagonist propranolol, which itself did not have any direct effect, inhibited the effect of isoproterenol in LR rats. The effect of isoproterenol in LR rats was not modified by alpha-agents. It is concluded that the beta-adrenergic, but not alpha-adrenergic, activity in the nucleus accumbens directs the individual-specific ability to retrieve spatial information under stressful conditions.