1. Figure 1. A schematic representation of the stress system
Figure 1. A schematic representation of the stress system. The CRH/AVP neurons are reciprocally connected with the noradrenergic neurons of the LC/NE system in a positive reverberatory circuit. The HPA axis is controlled by several negative feedback loops, which tend to normalize the time-integrated secretion of cortisol, yet glucocorticoids stimulate the amygdala and, hence, the fear center. Activation of the HPA axis leads to suppression of the GH/IGF-1, LH/testosterone/estradiol, and TSH/T₃ axes; activation of the sympathetic system increases IL-6 secretion. Chronic increases in cortisol, catecholamines, and IL-6 and chronic suppression of the GH/IGF-1, LH/T and TSH/T₃ axes lead to visceral obesity, hypertension, atherosclerosis, osteoporosis, and immune dysfunction and their sequelae resulting in increased morbidity and mortality. Symbols: Solid lines indicate stimulation; interrupted lines indicate inhibition. Abbreviations: HPA, hypothalamic-pituitary-adrenal; CRH, corticotropin-releasing hormone; AVP, arginine-vasopressin; LC/NE, locus ceruleus/norepinephrine system; GH, growth hormone; IGF-1, insulin-like growth factor-1; LH, luteinizing hormone; T, testosterone; TSH, thyrotropin; T₃, triiodothyronine; F, cortisol; NE, norepinephrine; E, epinephrine; IL-6, interleukin-6.
From: A Healthy Body in a Healthy Mind—and Vice Versa—The Damaging Power of “Uncontrollable” Stress
J Clin Endocrinol Metab. 1998;83(6): doi: /jcem
J Clin Endocrinol Metab | Copyright © 1998 by The Endocrine Society

2. Figure 2. A, (Left) Circadian pattern of cortisol secretion in nonstressed (NS, —) and chronically stressed (CS, .....), individuals. Note the blunting of the circadian rhythm in the latter, along with an augmented cortisol elevation in response to lunch. (Right) Cortisol response to a low dose of overnight dexamethasone (D). Note the increased suppressibility of nonstressed individuals vs. chronically stressed subjects. B, Dose-response curves of target tissue responses to cortisol: N, normal; HS, hypersensitive; R, resistant. The interrupted horizontal line represents a threshold effect beyond which long-term harm is done (Fig. 1, Table 1). Depending on the shift of the dose response curve to the left or right one would expect harmful or protective effects.
From: A Healthy Body in a Healthy Mind—and Vice Versa—The Damaging Power of “Uncontrollable” Stress
J Clin Endocrinol Metab. 1998;83(6): doi: /jcem
J Clin Endocrinol Metab | Copyright © 1998 by The Endocrine Society