Definition
A brain region linking the nervous and endocrine systems, producing releasing hormones that control the pituitary.
The hypothalamus is a small region at the base of the forebrain that coordinates the nervous and endocrine systems. Its neurons release peptide hormones into a portal blood supply that reaches the anterior pituitary, including GHRH, somatostatin, corticotropin-releasing hormone, thyrotropin-releasing hormone and gonadotropin-releasing hormone. Other hypothalamic neurons project to the posterior pituitary to release oxytocin and vasopressin. The arcuate nucleus integrates hormonal signals of energy status, such as leptin, insulin and ghrelin, through POMC and AgRP neurons acting on melanocortin receptors. This makes the hypothalamus a focus of peptide research on growth, energy balance, appetite and circadian rhythm.