Leptin accumulation in hypothalamic and dorsal raphe neurons is inversely correlated with brain serotonin content.

Food intake and energy balance are among the functions regulated by serotonin in the brain. Recent studies have shown an interaction of serotonergic system with leptin, a protein released from adipose tissue that inhibits feeding behavior and increases fuel expenditure. In this study, leptin labeled with digoxigenin was injected in the lateral cerebral ventricle of 5 young adult rats (4months old) and 5 aged rats (24months old) to assess the effect of aging on the accumulation of exogenous leptin by raphe and hypothalamic neurons.