Library · Molecule
Prolactin
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Prolactin is made by cells with a name of their own, the lactotrophs, which live in the anterior pituitary: the front part of a pea-sized gland that hangs beneath the brain. During pregnancy those lactotrophs grow in number.
What is odd about this hormone is how it is controlled. The hypothalamus keeps it suppressed all the time: dopamine coming from its arcuate nucleus reaches the lactotrophs through locks called D2 receptors and inhibits prolactin synthesis.
That is why the strongest stimulus works by releasing the brake rather than stepping on the gas. Nipple suckling inhibits dopamine release, and prolactin is set free. It is a faucet held shut by a hand, and it opens when the hand lets go.
Its job in the breast is twofold. It promotes growth of the mammary alveoli, the clusters where milk is made, and stimulates the synthesis of milk's components: lactose, casein, and lipids.
In brief
Prolactin is made by lactotrophs in the anterior pituitary, which grow in number during pregnancy.
The hypothalamus keeps it suppressed: dopamine from the arcuate nucleus acts on D2 receptors and inhibits its synthesis.
A faucet held shut by a hand that opens when the hand lets go.
The strongest stimulus is nipple suckling, which inhibits dopamine release and so takes that brake off.
It promotes growth of the mammary alveoli and stimulates the synthesis of lactose, casein, and lipids.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Prolactin, StatPearlsPublished
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