CEBPB and major depressive disorder: To confirm that C/EBPβ promotes HFD-induced depression via downregulating its downstream factor BDNF, we directly injected AAV-BDNF or AAV-GFP into the hippocampus of WT or Thy1-C/EBPβ Tg male mice fed an HFD for 8 weeks and continued the diet for another 4 weeks (Figure 7A).