Clenbuterol administration into the basolateral amygdala post-training enhances retention in an inhibitory avoidance task

The present study examined the effects of post-training infusions of the specific beta(2)-adrenergic agonist clenbuterol into the basolateral nucleus of the amygdala (BLA), on inhibitory avoidance retention. Male Sprague-Dawley rats were surgically implanted with cannulae aimed at the BLA. Animals were microinfused with different doses of clenbuterol (from 1.0 to 1000.0 ng) immediately after training, and retention was tested 48 h later. Clenbuterol dose dependently affected retention performances. Whereas the 10.0-ng dose of clenbuterol induced a significant increase in the performances, the groups injected with the other doses (1.0, 100.0, and 1000.0 ng) of clenbuterol did not differ from the vehicle-injected animals. These findings, indicating that clenbuterol enhanced retention of the inhibitory avoidance task, are in agreement with previous evidence showing that the adrenergic system of the amygdala is involved in the modulation of memory. Moreover, our data support the hypothesis that the memory-modulating effect of the amygdala adrenergic system is mediated, at least in part, by the activation of the P-adrenoceptors in the BLA. These findings provide further evidence that the BLA is an important brain region in integrating hormonal influences on memory storage. (C) 1999 Academic Press.