How does prolactin do its job

Symptoms can include the unwanted production of milk, disturbances to the menstrual cycle and symptoms due to oestrogen deficiency in women or testosterone deficiency in men. The vast majority of patients with a prolactinoma can be treated successfully using drugs which mimic the action of dopamine. The most commonly used is cabergoline.

The condition of having too little prolactin circulating in the blood is called hypoprolactinaemia. This condition is very rare and may occur in people with pituitary underactivity. A decrease in the amount of prolactin secreted can lead to insufficient milk being produced after giving birth.

Most people with low prolactin levels do not have any specific medical problems, although preliminary evidence suggests they might have reduced immune responses to some infections. About Contact Events News.

Search Search. You and Your Hormones. Students Teachers Patients Browse. Human body. Home Hormones Prolactin. It is difficult to point to a tissue that does not express prolactin receptors, and although the anterior pituitary is the major source of prolactin, the hormone is synthesized and secreted in many other tissues.

Overall, several hundred different actions have been reported for prolactin in various species. Some of its major effects are summarized here. In the 's it was found that extracts of the pituitary gland, when injected into virgin rabbits, induced milk production.

Subsequent research demonstrated that prolactin has two major roles in milk production:. The critical role of prolactin in lactation has been confirmed in mice with targeted deletions in the prolactin gene.

Female mice that are heterozygous for the deleted prolactin gene and produce roughly half the normal amount of prolactin show failure to lactate after their first pregnancy.

Prolactin also appears important in several non-lactational aspects of reproduction. In some species rodents, dogs, skunks , prolactin is necessary for maintainance of corpora lutea ovarian structures that secrete progesterone, the "hormone of pregnancy".

Mice that are homozygous for an inactivated prolactin gene and thus incapable of secreting prolactin are infertile due to defects in ovulation, fertilization, preimplantation development and implantation. Finally, prolactin appears to have stimulatory effects in some species on reproductive or maternal behaviors such as nest building and retrieval of scattered young.

The prolactin receptor is widely expressed by immune cells, and some types of lymphocytes synthesize and secrete prolactin. These observations suggest that prolactin may act as an autocrine or paracrine modulator of immune activity. Interestingly, mice with homozygous deletions of the prolactin gene fail to show significant abnormalities in immune responses.

A considerable amount of research is in progress to delineate the role of prolactin in normal and pathologic immune responses. High prolactin levels trigger the body to make milk for breastfeeding. In men, prolactin affects sperm production. Hyperprolactinemia is a condition of too much prolactin in the blood of women who are not pregnant and in men. Hyperprolactinemia is relatively common in women. About a third of women in their childbearing years with irregular periods but normal ovaries have hyperprolactinemia.

When this happens, a woman might have trouble getting pregnant or her breasts may start producing milk outside of pregnancy galactorrhea. Ninety percent of women with galactorrhea also have hyperprolactinemia. High prolactin levels interfere with the normal production of other hormones, such as estrogen and progesterone.

This can change or stop ovulation the release of an egg from the ovary. It can also lead to irregular or missed periods. Some women have high prolactin levels without any symptoms. In men, high prolactin levels can cause galactorrhea, impotence inability to have an erection during sex , reduced desire for sex, and infertility. A man with untreated hyperprolactinemia may make less sperm or no sperm at all.

Blood tests can measure levels of prolactin.