Stress: Endocrine Physiology and Pathophysiology

Stress constitutes a state of threatened homeostasis triggered by intrinsic or extrinsic adverse forces (stressors) and is counteracted by an intricate repertoire of physiologic and behavioral responses aiming to maintain/reestablish the optimal body equilibrium (eustasis). The adaptive stress response depends upon a highly interconnected neuroendocrine, cellular, and molecular infrastructure, i.e. the stress system. Key components of the stress system are the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system (ANS), which interact with other vital centers in the central nervous system (CNS) and tissues/organs in the periphery to mobilize a successful adaptive response against the imposed stressor(s). Dysregulation of the stress system (hyper- or hypo-activation) in association with potent and/or chronic stress can markedly disrupt the body homeostasis leading to a state of cacostasis or allostasis, with a spectrum of clinical manifestations. This chapter describes the organization and physiology of the stress system, focusing on its interactions with other CNS centers and endocrine axes, and reviews the existing evidence linking stress to pathophysiologic mechanisms implicated in the development of stress-related diseases affecting the endocrine, metabolic, gastrointestinal, and immune systems. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text, WWW.ENDOTEXT.ORG .