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 sp ecific beta(2)-adrenergic agonist clenbuterol into the basolateral nucleus of the amygdala (BLA), on inhibitory avoidance retention. Male Sprague-Dawl ey rats were surgically implanted with cannulae aimed at the BLA. Animals w ere microinfused with different doses of clenbuterol (from 1.0 to 1000.0 ng ) immediately after training, and retention was tested 48 h later. Clenbute rol dose dependently affected retention performances. Whereas the 10.0-ng d ose 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 clenbut erol did not differ from the vehicle-injected animals. These findings, indi cating that clenbuterol enhanced retention of the inhibitory avoidance task , are in agreement with previous evidence showing that the adrenergic syste m of the amygdala is involved in the modulation of memory. Moreover, our da ta 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 th e BLA is an important brain region in integrating hormonal influences on me mory storage. (C) 1999 Academic Press.