hypothalamushypofyseas

The hypothalamushypofyseas, commonly described as the hypothalamus–pituitary axis, is a core neuroendocrine system that links the hypothalamus with the pituitary gland. It coordinates neural and hormonal signals to regulate growth, metabolism, reproduction, stress responses and fluid balance. The axis operates through two anatomically distinct parts: the anterior pituitary (adenohypophysis) and the posterior pituitary (neurohypophysis).

Hormone signaling starts in the hypothalamus, which releases releasing or inhibiting hormones into the hypothalamo-hypophyseal portal system. These hormones travel to the anterior pituitary and regulate the secretion of tropic hormones such as ACTH, TSH, LH, FSH, and GH, as well as prolactin. The posterior pituitary stores and releases vasopressin (antidiuretic hormone) and oxytocin, which are produced by hypothalamic neurons and transported down their axons.

Regulation is largely pulsatile and tightly controlled by negative feedback. Hypothalamic releasing hormones include GnRH, CRH, TRH, GHRH and somatostatin, while dopamine inhibits prolactin release. The pituitary hormones act on peripheral targets (adrenal cortex, thyroid, gonads, liver and other tissues) to produce hormones such as cortisol, thyroid hormones, sex steroids, and growth factors, which in turn feedback to the hypothalamus and pituitary.

Clinically, dysfunction of the axis can lead to hypopituitarism or hyperpituitarism. Common conditions include pituitary adenomas causing excess ACTH, GH, or prolactin secretion, and disruptions of posterior pituitary function leading to diabetes insipidus. The hypothalamus–pituitary axis thus plays a foundational role in endocrine homeostasis and physiological adaptation.