While most research to date has focused on receptor-mediated signaling by adding exogenous norepinephrine or dopamine, a recent study has shown that NET is a potent regulator of the phenotype of sympathetic neuron–associated adipose macrophages and is implicated in obesity (10), showing that biogenic amine transporters can regulate macrophage functions. Here, SLC6A2 is linked to obesity due to melanocortin 4 receptor deficiency.