Glucocorticoid and β-adrenergic regulation of hippocampal dendritic spines

Abstract

Glucocorticoid hormones are particularly potent in enhancing memory formation. Notably, this occurs in close synergy with arousal, i.e. when norepinephrine levels are enhanced. Here we examined whether glucocorticoid and norepinephrine hormones regulate the number of spines in hippocampal primary neurons. We report that a brief administration of corticosterone or the β-adrenergic receptor agonist isoproterenol alone increases spine number. This effect becomes particularly prominent when corticosterone and isoproterenol are administered together. In parallel, corticosterone and isoproterenol alone increased the amplitude of mEPSCs, an effect that is not amplified when both hormones are administered together. The effects of co-application of corticosterone and isoproterenol on spines could be prevented by blocking the glucocorticoid receptor (GR)-antagonist RU486. Taken together, both corticosterone and β-adrenergic receptor activation increase spine number, and they exert additive effects on spine number for which activation of GRs is permissive.