The main function of dopamine secreted by the hypothalamus is to inhibit the secretion of prolactin from the anterior lobe of the pituitary gland, states the Massachusetts General Hospital Neuroendocrine Clinical Center. Too much prolactin can cause a pituitary tumor. The fact that dopamine inhibits both the synthesis and secretion of prolactin, may prove instrumental in preventing amenorrhea or lack of menstrual cycles and inhibit the spontaneous secretion of milk.
Inhibits Prolactin Secretion
Dopamine functions as the major brake on prolactin secretion in the body when secreted by neurons in the hypothalamus into the blood. When drugs interfere with this dopamine secretion, the result is often a prolactinoma or benign tumor of the pituitary gland that produces a hormone called prolactin. According to MayoClinic.com, complications of prolactinoma may include vision loss if left untreated, for the tumor may grow large enough to pinch the optic nerve.
When dopamine is blocked, hypopituitarism can occur. If the resulting pituitary tumors are large enough, the extra pressure on the pituitary gland can interfere with the functioning of other hormones regulated by the pituitary and cause hypothyroidism, growth hormone deficiency and adrenal insufficiency. Because prolactin production by the pituitary increases during pregnancy, if a woman does have a prolactinoma or pituitary tumor, she may experiences headaches and changes in vision.
If dopamine does not sufficiently reduce the production of prolactin, decreased bone density with the risk of osteoporosis can occur.
Helps Prevent Excessive Secretion of Milk
One of the major target organs of the multifunctional hormone prolactin secreted by the pituitary is the mammary gland, responsible for milk production. Prolactin is the chemical that stimulates milk production or lactogenesis after childbirth, acting in conjunction with insulin and cortisol to transcribe the genes encoding milk proteins. When there is insufficient dopamine production in the body, excessive milk secretion can occur as well as spontaneous milk secretion when breastfeeding has ceased.
Helps Prevent Anomalies in Reproductive Organs
When dopamine does not sufficiently brake the secretion of prolactin by the pituitary, amenorrhea or lack of menstrual cycles can occur. Inadequate dopamine protection of the pituitary gland can also cause hypogonadism in men, lessening their sex drive, decreasing their production of sperm and even causing impotence. Blockage of dopamine to the pituitary can also produce gynecomastia or breast enlargement in men.
Helps in the Secretion of Growth Hormone
Dopamine helps stimulate the pituitary gland to produce and secrete growth hormone. This hormone builds muscle, burns excess fat and helps improve mobility.
