The hypothalamus communicates with the anterior pituitary with the help of
The hypothalamus controls production and secretion of the anterior pituitary hormones. This control is exerted hormonally rather than by means of nerve axons as the anterior pituitary gland, unlike the posterior pituitary, is not derived from the brain. Hence, the anterior pituitary gland does not receive an axon tract from the hypothalamus like the posterior pituitary gland.
Neurons in the hypothalamus secrete releasing hormones and inhibiting hormones into a portal circulatory system and regulate the functions of the anterior pituitary. For example, Thyrotropin-Releasing Hormone (TRH) stimulates the release of Thyroid Stimulating Hormone (TSH), Corticotropin-Releasing Hormone (CRH) stimulates the release of Adrenocorticotropic Hormone (ACTH), etc.
The hypothalamus also secretes hormones that inhibit the release of certain anterior pituitary hormones. Till date, three such hormones have been discovered: somatostatin inhibits the secretion of Growth Hormone (GH); prolactin-inhibiting factor (PIF), found to be the neurotransmitter dopamine, inhibits the secretion of prolactin; and melanotropin-inhibiting hormone (MIH) inhibits the secretion of Melanocyte Stimulating Hormone (MSH).