Lipopolysaccharide (LPS) and macrophage colony-stimulating factor (M-CSF)—which are known to induce microglial activation and thereby produce depression-like behavior—have been found to attenuate the CUS-induced behavioral abnormalities via reversing CUS-induced reductions in the hippocampal microglia numbers (Tong et al., 2017). Here, CSF1 is linked to major depressive disorder.