MC4R and obesity due to melanocortin 4 receptor deficiency: Furthermore, the reduction in TSPO expression was not a direct result of the exposure to high-fat diet per se because we were able to detect a decrease in TSPO levels in mitochondrial extracts from WAT and BAT from the MC4R−/− monogenic mouse model of obesity which were maintained standard chow (Figs. 3 and 4C).