Mechanistically, PDE5 inhibitors produce an anti-inflammatory and neuroprotection effect by increasing expression of NOS and accumulation of cGMP and activating PKG, the signaling pathway of which is thought to play an important role in the development of several neurodegenerative diseases, such as AD, PD, and multiple sclerosis (MS) [74]. This evidence concerns the gene NOS2 and myeloid sarcoma.