Stress-induced release of pituitary beta-endorphin may be mediated by activation of the brain stem defence areas

In anaesthetized cats, electrical stimulation within the fore-brain defence areas evoked a marked increase in the plasma level of immunoreactive beta-endorphin which reached a peak after 5 minutes. Multiple immunoreactive peptides including "biologically-active" beta-endorphin-(1-31) were detected. It is suggested that the release of pituitary beta-endorphin during emotional stress results from the natural activation of the defence areas.