Researchers at the Karolinska revealed a novel mechanism for regulating the hormone prolactin. Prolactin is a hormone released from the pituitary gland. The release of prolactin is the signal that triggers breast milk production during nursing. The reason that why women normally do not produce milk, and men never do is for the reason that the release of prolactin is strongly inhibited by the signal matter dopamine. Dopamine is a neurotransmitter that occurs in a wide variety of animals including both vertebrates and invertebrates. Dopamine is the primary neuro-endocrine inhibitor of the secretion of prolactin from the anterior pituitary gland. Dopamine is secreted by cells known as ‘TIDA’ neurons in the hypothalamus in the brain.
The current study examined the electrical activity of the dopamine-producing TIDA cells. It also helps to understand in more depth the regulation of prolactin. The study revealed that the cells normally display an extremely rhythmical activity, with discharges every 20 seconds. Accordingly the scientists believe that this rhythmical behaviour lies behind the ability of the TIDA cells to function as a strong inhibitor of prolactin release. Furthermore the study has shown that TRH (thyrotropin-releasing hormone), a signal substance that is known to stimulate the release of prolactin, can interrupt the rhythmical signalling pattern of TIDA cells.
“It is known that rhythmical signalling makes it possible for nerve cells to release large quantities of signal substances,” says Christian Broberger, who has led the study. He also added that “Our results increase the possibility of being able to treat problems of prolactin release, not least the undesired effects that arise when using drugs that inhibit dopamine”.