Serotonin controls bone mass

A research group at Columbia University Medical Center, led by Gerard Karsenty, M.D., Ph.D., has discovered that the neurotransmitter serotonin controls bone growth. Serotonin is a chemical used in the brain to influence mood, appetite and sleep but only 5 percent of the serotonin in the body is produced in the brain. The rest of the body’s serotonin is produced in the duodenum, where its synthesis is controlled by a gene called Lrp5. The scientists discovered that when they turned the gene on or off they could control bone formation because the serotonin tells the skeleton when to slow production of new bone.
The group discovered that by stopping the intestine’s release of serotonin they could prevent osteoporosis in mice undergoing menopause. This is because by increasing the production of serotonin there is a decrease in bone mass but when the Lrp5 gene is deleted there is no effect on bone mass. The group also went on to verify that there are abnormal levels of serotonin in patients with two human bone diseases. Currently all but one osteoporosis drugs prevent the breakdown of old bone but do not generate new bone. The scientists are excited because developing a drug to control gastrointestinal release of serotonin should be relatively easy and would not need to enter the general circulation thus limiting side effects. The scientists did not find any problems in mice that could not produce serotonin in their intestines suggesting that the same would be true for humans.
Riley White
http://www.sciencedaily.com/releases/2008/11/081126122209.htm