Adaptation to Brief Stress *

The time-honored, useful, and frequently applied laboratory test of clinical medicine-the white blood cell count-is acquiring new meaning through recent discoveries in the basic sciences of medicine. The observation by Dougherty and White,16"17'19 and by Reinhardt, Aron, and Li,58 of the dissolution of lymphocytes by the action of adrenocortical hormone provokes reinterpretation of a number of physiological and pathological phenomena which have long been known to be accompanied by changes in the level of circulating leucocytes. The following discussion will be focused on an interpretation of the leucocytic changes which occur during brief stress. The adrenal cortex and its secretory activity are important factors in the adaptation of the total organism to stress situations.63 A great variety of stress situations such as exposure to cold, exhaustive physical effort, burning, scalding, injuries, hemorrhage, or infections induce activity of the adrenal cortex, with consequent metabolic changes which have been organized by Selye66 into a concept of the "adaptation syndrome." The variety of stress agents which provoke function of the adrenal cortex prompted Long49 to search for a common factor involved in all stress situations. He predicted this factor to be secretion of epinephrine and was able to support his concept experimentally by producing the adreno-cortical changes of stress by injection of appropriate doses of epinephrine. The physiological changes of adaptation induced by stress or the injection of epinephrine do not occur in hypophysectomized rats. Epinephrine, therefore, does not directly affect the adrenal cortex. Long postulates that the adrenocortical mechanisms of adaptation are initiated by secretion of epinephrine, which in turn induces pituitary secretion of adreno-cortico-trophic hormone with resulting secretion of adreno-cortical hormones and consequent adaptation phenomena.