We and others have shown that GLP-1 receptor agonists or analogs of GIP can improve synaptic transmission in the striatum, and protect synapses and neurons from PD-related stressors (Liu et al., 2015; Zhang et al., 2015; Li L. et al., 2016; Zhang and Hölscher, 2020; Hölscher, 2022). This evidence concerns the gene GIP and Parkinson disease.