Via the mediation of PAC1, PACAP has well-known neuroprotective effects in retinal neuronal cultures in vitro and against in vivo retinal degenerations including excitotoxic injury induced by glutamate and kainate, ischemic injury, degeneration caused by UV-A light, optic nerve transection and streptozotocin-induced diabetic retinopathy [7]. This evidence concerns the gene ADCYAP1 and retinal degeneration.