Corticosteroid Feedback Control of ACTH Secretion: Effect of Stress-Induced Corticosterone Secretion on Subsequent Stress Responses in the Rat1

Abstract

The stresses of electrical shock or laparotomy were repeated at various intervals up to 24 hr after the initial stress in an attempt to demonstrate inhibition of the second response as a consequence of corticosterone secreted after the first stress. In all cases the second response was equal to or greater in magnitude than the first. When the stress of prolonged (60-90 min) restraint was paired with the minor stress of injection several hr later, no inhibition of the corticosterone response to injection was observed.However, if the plasma corticosterone levels provoked by restraint stress were mimicked by injections of corticosterone or of ACTH, the subsequent response to injection stress was inhibited. We conclude from these, and previous studies in the adrenalectomized rat, that corticosterone does act to inhibit ACTH secretion, but that stress causes a prolonged period of hyper-responsiveness in either CNS or anterior pituitary components of the adrenocortical system. {Endocrinology 92: 1367, 1973) F EEDBACK control of ACTH secretion by circulating corticosteroids has been demonstrated both by the chronic increase in ACTH secretion which follows adrenalectomy and by the inhibition of ACTH secretion after corticosteroid treatment. However, it has been debated whether inhibition of stress-induced ACTH secretion occurs in the rat after treatment with smaller physiological quantities of corticosterone. Some have been unable to detect inhibition of stress responses after small doses of corticosterone (1-3), while others have demonstrated inhibition of stress responses while plasma corticosterone levels are rising as a result of treatment but are still in the low part of the physiological range (4-5). In part, the discrepant results appear to depend on the stress chosen to test for inhibition. It is abundantly clear that within the first few hr

Serum corticosterone concentrations in reproductively mature and inhibited deermice (Peromyscus maniculatus bairdii)

“…A similar finding was noted for the males from Population Blood corticosterone levels have been shown to be significantly elevated during acute and chronic stress of rats and some other laboratory animals (Friedman & Ader, 1968;Ganjam, Campbell & Murphy, 1972;Zimmerman, Smyrl & Critchlow, 1972;Cook, Kendall, Greer & Kramer, 1973;Dallman & Jones, 1973;Riegle, 1974;Barlow, Morrison & Sullivan, 1975), and an increase in plasma ACTH precedes the corticosterone elevation (Cook et al, 1973 (Terman, 1973b).…”

Struggling behavior during restraint is regulated by stress experience

“…In animals exposed to restraint after repeated swim in Experiment 2, ACTH and corticosterone levels are similar to those of acutely restrained rats. Therefore, repeated swim rats exhibit facilitated HPA responses to novel since their HPA responses match those of acutely stressed rats, as defined by Dallman and Jones [8]. We have previously observed facilitation of HPA responses to restraint after repeated swim [19].…”

Diabetes Impairs Hypothalamo-Pituitary-Adrenal (HPA) Responses to Hypoglycemia, and Insulin Treatment Normalizes HPA but not Epinephrine Responses

“…Studies in rats revealed both facilitated and inhibited HPA responses to hypoglycemia when a prior stressor was administered (28). Whether the response is facilitated or inhibited appears to depend on the intensity and the magnitude of the corticosterone response to the first stimulus (10).…”