GIPR and Parkinson disease: In this and our earlier study,50 we have collectively investigated brain uptake pharmacokinetics of 13 different peptide IRAs, including all those that are FDA-approved (albiglutide, dulaglutide, exenatide, liraglutide, lixisenatide, semaglutide, and tirzepatide), all the experimental dual IRAs that are equivalently potent activators of GLP-1 R and GIPR (Peptides 17, 18, 19, and 21 of Finan and Ma et al. [2013]), and all dual IRAs found therapeutic in animal models of AD and/or PD by Christian Hölscher.38 (DA1-JC, DA3-CH, DA4-JC, and DA5-CH).