We further identify the levels of both GR mRNA by real-time PCR and GR protein by western-blot in the hippocampus, and found that both GR mRNA (Figure 4a) and GR protein (Figure 4b,c) was significantly decreased after exposure to PM2.5. Therefore, we speculate that the PM2.5 exposure could have the strong correlation with mental and mood disorder. This evidence concerns the gene NR3C1 and mood disorder.