Prolactin (PRL) is a polypeptide hormone synthesized by the lactotropic cells of the anterior pituitary glad. Structurally, it is similar to two other polypeptide hormones namely, growth hormone and placental lactogen. PRL is a polypeptide hormone containing 199aa, while growth hormone and placental lactogen each have 191aa. There is about 100 ug of prolactin in the human pituitary gland, which is very small amount when compared to Growth hormone, which is present in 8-10mg. Prolactin target organ is the breast (mammary gland). Its main physiological action is not only to initiate but also to sustain lactation. The hypothalamus secretes dopamine, which has a direct effect of inhibition on the secretion of PRL. If dopamine is not available or absent the secretion of PRL is autonomous. PRL increases during sleep and pregnancy. In women giving birth and they do not breast feed then PRL decreases to its normal level in a short time. During breast feed, PRL remains elevated for about 3 months. Also during pregnancy the size of the pituitary gland increases which is due to the proliferation of lactotropic cells.
Intended for research use only. Not for use in human, therapeutic, or diagnostic applications.