NPTX2 and Parkinson disease: Moreover, the positive expression rate of NPTX2 protein in SNc tissues of PD mice was determined using IHC, which highlighted up-regulated positive expression rate of NPTX2 protein in the SNc tissues of PD mice injected with MPTP and MPTP + LV-oe-NC + agomir-NC compared to those injected with normal saline (p < 0.05).