Declarative memory after stress in humans: differential involvement of the beta-adrenergic and corticosteroid systems

To determine the role played by the beta-adrenergic and corticosteroid systems in the modulatory effects of stress on declarative memory function, 42 young men were administered a placebo, propranolol (beta-adrenergic blocker), or metyrapone (corticosteroid synthesis inhibitor) before being submitted to a psychological stress protocol. Immediately after stress, subjects viewed a neutral story, unrelated to the stressor. Short- (5 min post learning) and long-term (1 wk post learning) recall of the story was assessed. Placebo and propranolol groups showed significant stress-related increases in corticosteroid levels, whereas metyrapone prevented corticosteroid reactivity to the stressor. Stress triggered significant elevations in cardiac activity (heart rate, systolic and diastolic blood pressure levels) in all three groups, with the metyrapone group showing the strongest elevation in heart rate levels in response to stress. Compared with placebo, propranolol had no effect on short- and long-term recall of the story learned after stress, whereas metyrapone impaired short-term recall of the story, with no further effects on long-term declarative memory. These results suggest that, contrary to the beta-adrenergic system, the corticosteroid system is implicated in declarative memory function after stress in humans.