GLP1R and Parkinson disease: Due to the short half-life of naturally occurring GLP-1 in the human body, which makes it susceptible to degradation, we selected the GLP-1RAs exendin-4, characterized by a longer half-life and the ability to cross blood-brain barrier (BBB), to investigate the effects of long-term peripheral GLP-1RAs exendin-4 intervention on motor behaviors in MPTP-induced chronic PD mice.