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- induces mammary gland growth and milk secretion
- released steadily from pituitary during pregnancy and acutely in response
to sucking
- up-regulates immune function
- produced from lactotrophs which are stimulated by oestrogen
- may also be released by VIP, angiotensin II, substance P
- release inhibited by dopamine, released from hypothalamus
- hyperprolactinaemia caused by prolactinomas or dopamine antagonists can
depress gonadal function by destroying rhythm of LH release
- Mainly involved in the development of the female breast, and in the
initiation and maintenance of lactation shortly after childbirth. It is
released steadily from the pituitary during pregnancy, and acutely in
response to sucking.
- Control of release is mainly inhibitory via release of hypothalamic
dopamine into the portal circulation. Release is promoted by TRH, and also
by various stresses e.g. fear, hypoglycaemia.
- Hyposecretion of PRL leads to failure of lactation in women.
- Hypersecretion (hyperprolactinaemia) may result from a pituitary tumour or
hypothalamic disease. Infertility and menstrual complaints are the principal
symptoms; in men, a decreased libido, and impotence can occur.
14.2.3.1 prolactin = mammotrophin (from lactotroph cells)
| actions on breast; inhibits gonadal system |
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| control (only pituitary hormone negatively regulated by
hypothalamus) |
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| dysfunction: prolactinomas; dopamine-antagonising
drugs |
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