References - with notes
Phillips AC. Burns VE. Lord JM. Stress and exercise: Getting the balance right for aging immunity. [Review] [24 refs] Exercise & Sport Sciences Reviews. 35(1):35-9, 2007 Jan. UI: 17211192 "The reduced ability to produce the immune-enhancing hormone dehydroepiandrosterone (DHEA) (in the aged) results in an overrepresentation of immunosuppressive glucocorticoids in the circulation and may contribute to immunosenescence. Stress, whether physical or psychological, is broadly sensed by two systems within the hypothalamus: the HPA axis and the sympathetic-adrenal-medullary system. Stress induces the release of catecholamines from the adrenal medulla and both cortisol and DHEA from the adrenal cortex. Catecholamines and cortisol can both be immunosuppressive if chronically elevated. In contrast, DHEA is a precursor to sex hormones and is immune enhancing. Our own in vitro studies have shown that cortisol suppresses neutrophil function, and this can be overcome by coincubation with DHEA sulfate (5).