Volume 3 Issue 4

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Abby's Magazine - July/August 2015 | Page 7 Stress is an experience as old as humanity, yet the scientific understanding of stress has only developed over the past 70 years. Hungarian scientist Hans Selye pioneered modern stress studies during the 1930s and '40s when he discovered the importance of the adrenal glands in mediating the biological effects of stress. Since then science has discovered the LHPA (limbic-hypothalamus-pituitary-adrenal) axis as the neurohormonal regulator of the stress response. Whenever a person experiences something as stressful – whether an internal or external stressor – emotional reactions (often unconscious) in the limbic system of the brain trigger the hypothalamus to secrete CRH (corti- cotropin-releasing hormone). The CRH then triggers the pituitary gland to secrete ACTH (adrenocorticotropic hormone), which activates the adrenal glands to produce and release cortisol into the bloodstream. Although both CRH and ACTH have stress-mediating roles in their own right, cortisol is the chief "stress hormone." When cortisol blood levels become excessive, this turns off CRH release in a negative feedback loop. Yet as Shimmer and Parker note, "Circumstances of stress overcome negative feedback regulation of the HPA axis, leading to a marked rise in the production of corticosteroids [i.e. cortisol]." If the stresses in our life are only occasional, and we take adequate time for rest, relaxation and sleep to restore LHPA equilibrium, the occasional stress cortisol release will not be a problem. Yet if we live a typical modern American lifestyle, we are subject to chronic stress, with inadequate nutrition, rest, relaxation and sleep, and are subject to chronic excessive cortisol levels. It is important to realize that while everyone has the same psychobiologic stress machinery (the LHPA axis), the stressors that can trigger a stress reaction are infinitely variable. As Guyton and Hall point out, "…almost any type of physical or mental stress can lead within minutes to greatly enhanced secretion of ACTH and consequently cortisol as well, often increasing cortisol secretion as much as 20-fold." Even imaginary stressors, such as fearfully imagining a future event (e.g. an upcoming court trial or IRS audit), can trigger the LHPA axis into stress overreaction. The Dark Side of Cortisol Since cortisol is an essential stress protection hormone, why should we worry about too much of it? Some cortisol is essential for life. Serious cortisol deficiency produces Addison's disease, a potentially fatal illness. Cortisol is necessary for normal brain, immune, muscle and blood sugar function, and blood circulation. Yet excessive cortisol is equally damaging. S t r e s s a n d C o r t i s o l : T h e P l a g u e o f t h e 2 1 s t C e n t u r y Stress and Cortisol: The Plague of the 21st Century by James South, MA

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