SNCA and Parkinson disease: Some studies postulate that the pathogen of PD originates from the enteric nervous system (ENS) and spreads to the central nervous system (CNS) via the vagus nerve, in turn passing through the dorsal motor nucleus of vagus (DMV) and the SN, which are involved in energy metabolism regulation [5-7] Kim et al. confirmed that the phosphorylation of serine 129 of alpha-synuclein (pSer129-α-Syn) was detected in multiple central nuclei, including the DMV and SN, after the injection of pathological α-Syn fibrils into the duodenal and pyloric muscularis layers [8].