Question

The hypothalamus controls the anterior pituitary by means of

• A. Releasing hormones
• B. Second messengers
• C. Antibodies
• D. Inhibiting hormones

Answer 1

Answer: (A), (D)

The correct options are
A Releasing hormones
D Inhibiting hormones

The anterior pituitary gland, unlike the posterior pituitary, is not derived from the brain and does not receive an axon tract from the hypothalamus like the posterior pituitary gland. Nevertheless, the hypothalamus controls production and secretion of the anterior pituitary hormones. This control is exerted hormonally rather than by means of nerve axons. 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 TSH, corticotropin-releasing hormone (CRH) stimulates the release of 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 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 MSH.