PTGDS and obesity due to melanocortin 4 receptor deficiency: In this study, we investigated the effects of HFD on obesity and insulin resistance in two distinct types of adipose-specific L-PGDS gene knockout (KO) mice: fatty acid binding protein 4 (fabp4, aP2)-Cre/L-PGDSflox/flox and adiponectin (AdipoQ)-Cre/L-PGDSflox/flox mice.