Breasts are a variety of endocrine hormone target organs, therefore, breast growth and development of its various physiological functions of play are dependent on a variety of related endocrine hormones together. If one of one or several hormone disorders, or various hormones imbalance between the bound, directly or indirectly affect the status of the mammary gland and its physiological functions.
A direct effect on the mammary gland hormones
Female hormone (estrogen, E): primarily by secretion of ovarian follicles, adrenal and testis may secrete a small amount of estrogen, estrogen mid-and late pregnancy is mainly derived from the placenta choriocarcinoma. The physical activity of estrogen is the strongest estradiol (E2). In puberty, ovarian follicles mature to start a large number of estrogen secretion.
Estrogen can promote breast ductal epithelial hyperplasia, breast duct and lobular development of the surrounding connective tissue, so that the extension and branching of duct. Effect of estrogen on the formation of lobular breast and breast mature, and can not stand alone role, there must be a complete system control of pituitary function. Of estrogen can stimulate the synthesis and release of anterior pituitary prolactin, thereby contributing to development of the mammary gland; and large doses of estrogen can also compete prolactin receptor, thus inhibiting the role of prolactin in lactation. During pregnancy, other hormones such as estrogen-progestin, under such synergies, but also promote the development and acinar formation of milk. Exogenous estrogen in ovariectomized animals can breast tissue, their cell proliferation index was significantly higher than normal breast tissue. Estrogen can also make breast vasodilatation, increased permeability.
Progesterone (progesterone, P): also known as progesterone is mainly secreted by the corpus luteum, pregnancy secreted by the placenta.
Progesterone is the most physiologically active progesterone, whose main role is to facilitate the development of breast lobules and acini, in the estrogen-stimulated mammary duct development foundation, the breast to be fully developed. Large doses of progesterone inhibit the role of prolactin in lactation. Progesterone on breast development impact, not only have a synergistic effect of estrogen, but also must have a complete functional system of the pituitary. Experiments show that the removal of the pituitary of ovariectomized rats, mammary gland total lack of response to progesterone. Progesterone may be by stimulating pituitary prolactin secretion, it could be mammary epithelial cells by increasing the prolactin response to sexual and have completed their role in mammary gland development.
Prolactin (prolactin, PRL): secreted by the pituitary acidophilic cell a protein hormone.
Its main role is to facilitate the growth of breast development, launch and maintenance of lactation. Prolactin and mammary epithelial cells, PRL receptor, resulting in a series of responses, including stimulating the synthesis of α-lactalbumin, uracil nucleotide conversion, mammary cells, conversion of sodium and fatty acid synthesis, stimulate the mammary acinar development and to promote the formation and secretion of milk.
In puberty, the female hormone prolactin, progesterone and other hormones working together, can promote breast development; breast during pregnancy can be fully developed, so that terminal duct lobular develop into a small acini, in order to breast-feeding ready for it. Pregnancy lot of estrogen and progesterone inhibits the role of prolactin in lactation; childbirth, estrogen and progesterone levels decreased rapidly, lifting the inhibition of prolactin, while prolactin secretion is also a significant increase in breast start lactating. Since then, with the establishment of regular breast-feeding the baby constantly sucking reflex arising from the nipple to stimulate the pituitary secretion of prolactin, so that lactation can be maintained for several months to several years. Prolactin secretion by the hypothalamic prolactin inhibitory factor and prolactin releasing factor and other regulating hormones.
Drugs such as levodopa and bromocriptine inhibit the secretion of prolactin; thyrotropin-releasing hormone, 5 - serotonin and certain drugs (such as reserpine, chlorpromazine), etc. can promote the secretion of prolactin; a small dose of of estrogen and progesterone can promote the secretion of pituitary prolactin, and large doses of estrogen and progesterone is inhibited prolactin secretion.
Indirect effects on the mammary gland hormones
Follicle-stimulating hormone (follicle-stimulating hormone, FSH): secreted by the anterior pituitary. Main role is to stimulate the ovarian secretion of estrogen, and thus physiological functions of the mammary gland development and regulation of an indirect effect.
Luteinizing hormone (luteinizing hormone, LH): secreted by the anterior pituitary. The main role is to stimulate the production of progesterone and thus physiological functions of the mammary gland development and regulation of an indirect effect.
Oxytocin (oxytocin): posterior lobe secretion by the pituitary gland. In the breast-feeding for promoting the role of the milk discharge.
Male hormone (androgen): in the female by the secretion from the adrenal cortex. A small amount of time can promote the development of the mammary gland; while a large number of hours can be a disincentive.
Other hormones: such as GH (growth hormone, GN), adrenal cortex hormones (adrenocortico-hormo ne), thyroid hormone (thyroxine) and insulin (insulin) and so on, these hormones on the mammary gland development and play an indirect role in a variety of functional activities
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