5-HT and bone biology.

Bone formation and bone resorption, the two processes occurring constantly and in a balanced fashion throughout the skeleton, are regulated by signals as various as local and low range growth factors, hormones, and neuronal outputs. Adding to the long list of molecules involved in these regulations, gut-derived and brain-derived serotonin were recently shown to control one or both of these processes. They do so, however, by targeting different cells, respectively acting as a hormone and as a neuromediator. Moreover, while brain serotonin positively regulates bone mass accrual peripheral serotonin is a potent inhibitor of bone formation. These findings raise the prospect that pharmacologically manipulating serotonin production could therefore become a novel strategy to treat bone loss disorders.