Which hypothalamic factor inhibits prolactin secretion?

Which hypothalamic factor inhibits prolactin secretion?

• A. Dopamine
• B. TRH
• C. GnRH
• D. CRH

Answer: (A)

Prolactin secretion is governed mainly by inhibition from dopamine produced by the hypothalamus. Dopamine travels to the anterior pituitary and binds to D2 receptors on lactotrophs, reducing intracellular signaling (like cAMP and calcium) that would normally promote prolactin release. This inhibitory tone keeps prolactin levels in check; blocking dopamine or removing its signal leads to increased prolactin. Other factors can modulate prolactin, but they don’t provide the primary inhibitory control. TRH, for example, can stimulate prolactin release, while GnRH drives gonadotropins (LH/FSH) and CRH drives ACTH. In practice, boosting dopamine signaling with dopamine agonists lowers prolactin in hyperprolactinemia.

Prolactin secretion is governed mainly by inhibition from dopamine produced by the hypothalamus. Dopamine travels to the anterior pituitary and binds to D2 receptors on lactotrophs, reducing intracellular signaling (like cAMP and calcium) that would normally promote prolactin release. This inhibitory tone keeps prolactin levels in check; blocking dopamine or removing its signal leads to increased prolactin.

Other factors can modulate prolactin, but they don’t provide the primary inhibitory control. TRH, for example, can stimulate prolactin release, while GnRH drives gonadotropins (LH/FSH) and CRH drives ACTH. In practice, boosting dopamine signaling with dopamine agonists lowers prolactin in hyperprolactinemia.