Prolactin
Prolactin is a hormone found in the human body. It is secreted by lactotrope cells in the adenohypophysis of the anterior pituitary gland. Prolactin is a single chain polypeptide of 199 amino acids. It is classified as a peptide hormone.
Secretion and Production
Prolactin is produced in and secreted from the lactotrope cells in the adenohypophysis of the anterior pituitary gland. Additionally, it is produced in other tissues including the breast and the decidua.
The most important effect of prolactin is to stimulate the mammary glands to produce milk. During pregnancy, high levels of progesterone inhibit the secretion of milk. After a pregnant woman gives birth, their levels of progesterone lower and milk ejection is possible.
Another effect of high prolactin levels is the suppression of ovulation by the inhibition of both follicle-stimulating hormone and gonadotropin-releasing hormone. This effect is what inhibits menstrual cycles in breastfeeding mothers. Additionally, because it inhibits ovulation, it is an effective means of birth control in breastfeeding mothers.
The final effect of prolactin is that it provides the body with sexual gratification after sexual acts. Prolactin represses the effect of dopamine, which is responsible for sexual arousal, thus causing the male’s refractory period. The amount of prolactin secreted can be an indicator for the amount of sexual satisfaction and relaxation. However, unusually high amounts of prolactin can be responsible for impotence.
Pharmacological Uses
Synthetic prolactin is commonly used in women to promote or create lactation. For example, if a woman who has adopted a child wishes to breastfeed it, she can receive synthetic prolactin in order to force her body to produce breast milk even through she was never pregnant. Additionally, women who produce insufficient amounts of breast milk after childbirth can be administered synthetic prolactin in order to promote lactation.