A major advantage of rotenone in modelling PD is that upon chronic ingestion of rotenone, alpha-synuclein accumulates in the enteric nervous system (ENS), which then induces transneuronal distribution of misfolded alpha-synuclein to the hind- (dorsal motor nucleus of the vagus) and midbrain (SNpc) of experimental animals [16,17,18]. This evidence concerns the gene SNCA and Parkinson disease.