"Science and technology: Genes, brain, stress and evolution"

Life exists through maintenance of a complex dynamic equilibrium, or homeostasis, that is constantly challenged by intrinsic or extrinsic adverse forces, or stressors. Stress is the state of threatened or perceived as threatened homeostasis re-established by a complex repertoire of physiologic and behavioral adaptive responses. Neuroendocrine hormones play crucial roles in the coordination of both basal and threatened homeostasis and mediate the pathogenesis of dyshomeostatic or cacostatic disease states. The stress response is subserved by the stress system, located both in the central nervous system and periphery. The principal central effectors are highly interlinked, and include the hypothalamic corticotropin-releasing hormone, arginine vasopressin, and proopiomelanocortin-derived peptides, and the brainstem locus caeruleus and central autonomic norepinephrine centers. The targets of these effectors are the brain, including the executive/cognitive, reward, and fear systems and the wake/sleep centers, the growth, thyroid and reproductive axes, as well as the gastrointestinal, cardiorespiratory, metabolic, and immune systems. Appropriate basal activity and responsiveness of the stress system to stressors is a crucial prerequisite for a sense of wellbeing, successful performance of tasks, and positive social interactions. By contrast, inappropriate basal activity and responsiveness of this system may impair growth, development and body composition, and account for many neurobehavioral, endocrine, metabolic, cardiovascular, autoimmune, and allergic disorders.