noun Biochemistry.
an anterior pituitary polypeptide hormone that stimulates lactation by the mammary glands at parturition in mammals, the activity of the crop in birds, and in some mammalian species the production of progesterone by the corpus luteum.
Also called anterior pituitary hormone, lactogenic hormone, luteotropin.

1930–35; pro-1 + lact- + -in2 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
prolactin (prəʊˈlæktɪn)
follicle-stimulating hormone See also luteinizing hormone luteotrophin, Also called: luteotrophic hormone a gonadotrophic hormone secreted by the anterior lobe of the pituitary gland. In mammals it stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation

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American Heritage
Medical Dictionary

prolactin pro·lac·tin (prō-lāk'tĭn)

Abbr. PRL A pituitary hormone that stimulates and maintains the secretion of milk. Also called lactogenic hormone, lactotropin, luteotropic hormone, luteotropin.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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American Heritage
Science Dictionary
prolactin   (prō-lāk'tĭn)  Pronunciation Key 
A protein hormone secreted by the anterior portion of the pituitary gland that stimulates and maintains the secretion of milk in mammals.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica


a protein hormone produced by the pituitary gland of mammals that acts with other hormones to initiate secretion of milk by the mammary glands. It also acts to maintain the corpus luteum of the ovary, which is the source of the female sex hormone progesterone. Its function in males is not known. In humans prolactin is similar to human growth hormone.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
If prolactin levels remained high, milk could follow.
These drugs decrease prolactin levels and shrink the tumor.
After childbirth, prolactin levels fall as the internal stimulus for them is removed.
Human prolactin receptors are insensitive to mouse prolactin.
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