ABSTRACT
Activation of the adrenal medulla classically has been related to the phenomenon of stress. Both psychologic and physiologic stressors have been used in human subjects. More severe physiologic stressors have been tested for their efficacy in activating the sympathoadrenal system in experimental animals. Post-training ingestion of glucose has been shown to improve retention of various learned responses. Post-training injections of glucose improved retention of a conditioned emotional response in both demedullated and control rats, thus indicating that the adrenal medulla is not involved in this phenomenon. Neurohormones of both the adrenal cortex and medulla were shown to be involved in the retention of a behavioral response after stress. Prolonged foot-shock, intermittent cold water swim, and immobilization all produced an opiate-mediated form of stress-induced analgesia because administration of naloxone blocked pain suppression induced by the treatments. Exposure of such chronically stressed animals to a unique stressor elicits an exaggerated sympathoadrenal response.
