This chapter discusses how the hypothalamic-pituitary-adrenocortical (HPA) system is essential for the maintenance of internal homeostasis and a major mediator component of the body's adaptive response to internal or external stressors. The HPA system consists of the paraventricular nucleus (PVN) located in the hypothalamus, the pituitary gland, and the adrenal cortices. Glucocorticoids regulate a variety of biologic processes and exert profound influences on many physiologic functions. They are essential for the maintenance of basal and stress-related homeostasis, while at pharmacologic doses they exert catabolic effects, mainly on the skeletal muscles and the bones, and potent, mostly suppressive effects on the immune system. Patients with major depression, particularly the melancholic type, demonstrate sustained hyperactivity of the HPA system and subsequent elevation of cerebrospinal fluid CRH, plasma ACTH and serum cortisol concentrations, possibly caused by mental stress. Destructive lesions in the pituitary gland can cause hypofunction of the HPA system and secondary adrenal insufficiency.
|Title of host publication||Handbook of Neuroendocrinology|
|Number of pages||19|
|Publication status||Published - 2012|
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