In contrast, since PACAP binds with high affinity to PAC1, the anti-atherosclerotic effect of the PAC1 agonist Maxadilan perfectly corresponded to the loss of endogenous atheroprotection previously described in PACAP−/−/ApoE−/− mice, showing the aggravation of atherosclerosis (as described by Rasbach et al., 2019 [5]), which indicates that PACAP may act as an endogenous atheroprotectant. This evidence concerns the gene ADCYAP1 and atherosclerosis.