LEP and major depressive disorder: Qin et al. showed that chronic unpredictable mild stress (CUMS) was able to induce severe depression-like behavior, neuroinflammation and reduced PPARγ expression in leptin-deficient (ob/ob) mice compared to wild-type/C57BL/6J mice, suggesting that PPARγ mediates an activated phenotype of microglia, which may be related to the susceptibility of stressed ob/ob mice to develop depression [72].