SNCA and Parkinson disease: Although non-motor features such as gastrointestinal and sleep disturbances often precede motor impairments and are critical to PD pathogenesis, the mechanisms underlying their onset and progression remain insufficiently characterized.<h4>Methods</h4>To investigate the sequential development of motor and non-motor symptoms in a model of experimental parkinsonism, we injected alpha-synuclein (αSyn) preformed fibrils (PFFs) into the duodenum and antrum of wild-type mice, establishing a gut-brain axis model of PD.