When the cells were exposed to the AD insult, i.e., 48-h treatment of Aβ1–42 oligomer, UFP-512, the specific DOR agonist, significantly decreased BACE1 protein level by 31.2% (p < 0.05, Figure 4B) whereas the addition of naltrindole reversed the effects induced by UFP-512. Here, BACE1 is linked to Alzheimer disease.