[Stress-induced analgesia. The role of corticosteroids]

Non-opioid stress-induced analgesia was studied in anesthetized rats, which were treated with electroshock (0.7 mA, 15 sec on, 15 sec off, 3 min duration) delivered through fixed hind limb electrodes. Tail-flick threshold of electroshock stimulation of the tail was used as a measure of analgesia. Stress-induced analgesia was decreased by adrenalectomy. Medullectomy did not block analgesic effect of stress. These results suggest that corticosteroids, but not enkephalins of adrenal medulla, provide the analgesia induced by short-term stress.