GIPR and Parkinson disease: As indicative of improved autophagy function and the associated amyloid removal, GLP-1R or GLP-1R/GIPR dual agonists reduced α-synuclein accumulation (Zhang et al., 2019; Lv et al., 2021; Zhang L.Y. et al., 2021) and the deposition of insoluble α-synuclein/p-α-synuclein and ubiquitin inclusions (Yun et al., 2018) in dopaminergic neurons in the brains of various PD in vivo models.