THE AGE OF BEGINNING REACTIVITY OF THE PITUITARY-ADRENOCORTICAL SYSTEM TO STRESS IN THE MOUSE1

Abstract

Introduction IT IS well known that adult animals respond to stressing stimuli by the release of adrenocorticotrophic hormone (ACTH) from the anterior pituitary which in turn stimulates the adrenal cortex to produce and release glucocorticoids. The problem still remains as to when in the development of an organism the pituitary-adrenocortical system matures sufficiently to carry out this function. Although a functional inter-relationship between the hypophysis and the adrenal cortex has been shown in the fetus (Jost, 1948; Wells, 1948; Kitchell, 1950; Kitchell and Wells, 1952a, b; and others) there is abundant evidence that the homeostatic mechanism for bringing about activation of the adrenal cortex has not reached functional maturity at birth. Jailer (1949, 1950) reported that stress by cold gave no significant depletion of adrenal ascorbic acid in the infant rat until the sixteenth day of life, whereas he was able to secure such depletion with epinephrine on the eighth day and with ACTH on the fourth.