Fig. 1.

Glucocorticoid effects on memory consolidation for object recognition training require noradrenergic activation. Data represent discrimination index (%) on a 24-h retention trial, expressed as mean ± SEM. (A) Effects of immediate posttraining administration of the β-adrenoceptor antagonist propranolol (3.0 mg/kg, s.c.) on corticosterone-induced enhancement of object recognition memory in naïve rats. ∗∗, P < 0.0001 vs. vehicle (n = 8–12 per group). (B) Effect of coadministration of the α₂-adrenoceptor antagonist yohimbine (0.3 mg/kg, s.c.) with corticosterone on object recognition memory in habituated rats. ∗∗, P < 0.0001 vs. vehicle (n = 9–17 per group). (B Inset) Effect of posttraining injections of yohimbine (0.3 mg/kg, s.c.) and corticosterone (1.0 mg/kg, s.c.) separated by a 4-h delay. Y→C, yohimbine administered immediately after training and corticosterone 4 h later; C→Y, corticosterone administered immediately after training and yohimbine 4 h later.