ABSTRACT
There is an amazingly complex network of molecular pathways and receptors dedicated to the handling of stress at the cellular level. This chapter will provide the reader with an up-to-date overview of these networks and the key players at molecular, cellular, and organ levels. It hopes to shed light on how the stress response provides a unifying explanation for virtually all chronic diseases of aging, which is often the most underappreciated element in medicine and public health. Allostatic mediators include hormones, autonomic neurotransmitters, and neuromodulator monoamines, and immune cell cytokines. On the other hand, homeostasis represents resistance of vital organ system parameters to change. The origin of neuroendocrinology as a modern area of medicine can be traced to the 1940's when the major hypothalamic pituitary adrenal axis (HPA), the canonical stress response system, began to be uncovered. The transition to allostatic overload accompanies an attractor state of primary allostatic parameters that evolve to greater adrenergic and proinflammatory dominant states.
