Metyrapone decreases locomotion acutely.

Metyrapone is a glucocorticoid synthesis inhibitor known to induce a stress-like biological syndrome, but also to limit stress-related behaviours. Since stress is usually associated to an increased locomotion, the aim of the study was to determine whether metyrapone will increase, decrease or respect locomotion. Forty rats were placed in infrared actimeters to study spontaneous locomotion before and after injecting 150 mg kg(-1) of either metyrapone (n=20) or saline (n=20).