NPAS4 and Brain atrophy: We investigated changes in gene expression in the hippocampus on the third day of stress loading, and clarified the difference between SAMP10 and ddY mice, that is, the expression levels of neuronal PAS domain protein 4 (Npas4) and lipocalin 2 (Lcn2) were involved in the brain atrophy and stress vulnerability of SAMP10 ice, and the changed expression of Npas4 and Lcn2 was prevented by theanine ingestion [4].