Over 30 000 Swedish men and women may have raised levels of prolactin. Women who are pregnant or breast feeding have naturally raised levels of prolactin, but stress, some medicines and benign brain tumours can also lead to raised levels of the hormone. In many cases doctors don’t know what causes the rise in hormone levels. In women, an abnormally high level can cause menstrual disturbances and infertility, and may also result in insulin resistance.
“In recent years scientists have also recognised the role of prolactin in the development of obesity, but little research has been done into the precise mechanism by which prolactin regulates metabolism,” says Louise Nilsson.
In her thesis Louise Nilsson shows that there are receptors for the breast feeding hormone in human fatty tissue.
“We have demonstrated that prolactin reduces the ability of fatty tissue to store sugar and fat, which then could accumulate in the blood and certain tissues instead. This in turn increases the risk of cardiovascular disease.”
Prolactin also affects the body’s ability to metabolise fat. An ongoing study suggests that the hormone impairs the body’s ability to maintain a balanced metabolism.
“When fatty tissue receives signals from prolactin, it reacts by reducing the production of another hormone called adiponectin, which is important for the metabolism of a variety of nutrients,” explains Louise Nilsson.
FACTS ABOUT PROLACTIN
Prolactin is a hormone produced by the pituitary gland in the brain. It stimulates the production of milk in the breast and also inhibits hormone production in the ovaries and testicles. Prolactin levels are considerably raised in pregnancy, and prolactin secretion is also stimulated by breast feeding.
Doctoral thesis from the Sahlgrenska Academy, Institute of Neuroscience and Physiology
Title of thesis: Effects of prolactin on metabolism – changes induced by hyperprolactinemia
Link to the thesis: http://hdl.handle.net/2077/19049