title: Glucocorticoid enhancement of memory requires arousal-induced noradrenergic activation in the basolateral amygdala.
abstract: Considerable evidence indicates that glucocorticoid hormones enhance the consolidation of long-term memories for emotionally arousing experiences but not that for less arousing or neutral information. However, previous studies have not determined the basis of such arousal-induced selectivity. Here we report the finding that endogenous noradrenergic activation of the basolateral complex of the amygdala (BLA) induced by emotional arousal is essential in enabling glucocorticoid memory enhancement. Corticosterone administered immediately after object recognition training enhanced 24-h memory of naïve male rats but not that of rats previously habituated to the training context in order to reduce novelty-induced emotional arousal. The beta-adrenoceptor antagonist propranolol administered either systemically or into the BLA blocked the corticosterone-induced memory enhancement. Further, in habituated rats, corticosterone activated BLA neurons, as assessed by phosphorylated cAMP response element binding (pCREB) immunoreactivity levels, and enhanced memory only when norepinephrine release was stimulated by administration of the alpha(2)-adrenoceptor antagonist yohimbine. These findings strongly suggest that synergistic actions of glucocorticoids and emotional arousal-induced noradrenergic activation of the BLA constitute a neural mechanism by which glucocorticoids may selectively enhance memory consolidation for emotionally arousing experiences.
authors.affiliation: Center for the Neurobiology of Learning and Memory, and Department of Neurobiology and Behavior, University of California, Irvine, CA 92697-3800, USA. broozend@uci.edu
authors.forename: Benno
authors.initials: B
authors.lastname: Roozendaal
authors.forename: Shoki
authors.initials: S
authors.lastname: Okuda
authors.forename: Eddy A
authors.initials: EA
authors.lastname: Van der Zee
authors.forename: James L
authors.initials: JL
authors.lastname: McGaugh
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000679:Amygdala / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001143:Arousal / Q000187:drug effects / Q000502:physiology*; D003345:Corticosterone / Q000494:pharmacology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000737:chemistry / Q000378:metabolism; D006185:Habituation, Psychophysiologic / Q000502:physiology; D008297:Male; D008568:Memory / Q000187:drug effects* / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology*; D010766:Phosphorylation; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D017362:Cyclic AMP Response Element-Binding Protein; D015016:Yohimbine; D011433:Propranolol; D003345:Corticosterone; D009638:Norepinephrine