The hormone serotonin is probably best known for its role in the brain; however, it is also made elsewhere in the body where it regulates multiple physiological processes.
Serotonin that is made in the gut is reduces the proliferation of bone cells (osteoblasts) and scientists have suggested that blocking gut serotonin might be method for treating osteoporosis.
To determine if this is a feasible treatment method, researchers led by Stavroula Kosteni at Columbia University set out to determine exactly how gut serotonin exerts its effects on bone mass.
In a study published in the Journal of Clinical Investigation, Kosteni and colleagues report that the level of gut-made serotonin released into general circulation determines the activity of a protein known as FoxO1.
FoxO1 works as a transcription factor, or a protein that controls which genes are expressed. Depending on the level of serotonin, FoxO1 can interact with a protein that promotes bone formation, CREB, or a protein that blocks bone formation, ATF4.
Fluctuations in serotonin levels can therefore either promote or block the formation of new bone cells.
Article: FOXO1 orchestrates the bone-suppressing function of gut-derived serotonin, http://www.jci.org/articles/view/64906?key=f305fffbaadd1aebaa12