GLP1R and Parkinson disease: However, long-acting analogues that include Exendin-4 (Exenatide), a GLP-1R agonist originally isolated from the saliva of the lizard Heloderma suspectum and now synthesized, are approved for the treatment of T2DM30,31 and have shown promising actions in PD animal models26 and clinical trials of PD patients32,33.