These include heart disease, where PACAP is proposed to act at PAC1 to attenuate inflammatory atrial fibrosis and atherosclerogenesis [1], neuropsychiatric disorders, in particular depression and post-traumatic stress disorder [2], migraine [3], dry eye syndrome [4], nerve injury-induced allodynia [5], and neuroprotection from tissue damage in stroke and ischemia [6–10]. This evidence concerns the gene ADCYAP1 and major depressive disorder.