ADCYAP1 and Parkinson disease: Likewise, in a different murine PD model [mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)], intravenous injection of PACAP-27 prevented neuronal loss in the substantia nigra (Wang et al., 2008) and rescued learning deficit (Deguil et al., 2010).