The hormone prolactin is produced by the pituitary gland in the brain and then travels via the bloodstream to cells throughout the body, where it exerts multiple reproductive and metabolic effects, most notably on the breast where it is the master regulator of lactation. In recent years researchers have found that prolactin is also produced by some tissues outside the brain, however little is known about the functions of extra-pituitary prolactin or how its production is regulated in these tissues.
