Figure 1. Model of the leptin-dependent central control of bone mass, appetite and energy expenditure. Leptin inhibits release of brainstem-derived serotonin, which favors bone mass accrual and appetite through its action on hypothalamic neurons. Serotonergic neurons are in blue; VMH, ventromedial hypothalamus; ARC, arcuate; VMH is in purple and arcuate is in green.