To determine whether this regulation of TSPO expression within mitochondria is specific to diet-induced obesity, we measured relative TSPO ligand binding using 3H-PK11195 in mitochondrial extracts from WAT and BAT from MC4R−/− mice, a genetic model of obesity, as compared to their wild-type littermate controls. This evidence concerns the gene MC4R and obesity due to melanocortin 4 receptor deficiency.