Prolactin physiologic action

The main actions of prolactin in mammals are concerned with the mammary gland (see below). Lactogenic and mammogenic actions are also shown by several other hormones, including the placental lactogens found in man and many other mammalian species [5-7]. The physiological role of these placental hormones has not been fully established, but it does seem likely that their biochemical mode of action will prove to be similar in some respects to that of prolactin. Their structural relationships to GH and prolactin are discussed in Chapter 13. 

The source of the ergot strongly influences the type of alkaloids present, as well as the clinical picture of ergotism [171]. The ergot alkaloids have three types of physiological effects they cause contraction of smooth muscle, they block the action of serotonin and adrenaline, and they act on the hypothalamic-pituitary system to inhibit the secretion of prolactin. These properties have led to their being used to induce uterine contractions, to relieve migraine headaches, and to treat prolactin-dependent disorders. 

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