A more recent study has shown that pioglitazone, a highly selective agonist for peroxisome proliferator-activated receptor γ (PPARγ), exerts an antidepressant-like activity through PPARγ-mediated amelioration of M1/M2 microglial imbalance in chronic mild stress-induced depression-like model mice [24]. This evidence concerns the gene PPARG and major depressive disorder.