NPY and Alzheimer disease: As shown in Figure 1B, the protein expression of TH, NPY, GAP43 and PGP9.5 in RV was significantly up‐regulated in AV group (vs S group) (P < 0.01), protein GAP43 and PGP9.5 were significantly down‐regulated in AD group (vs AV group) (P < 0.05, P < 0.01).