In turn, DOR activity exhibits an anxiolytic profile, which is widely supported by experimental results gathered in mice following ablation of one of the functional variants (DOR1) of this receptor, which triggers the appearance of anxiolytic effects both in the Elevated Plus-Maze and the Light-Dark Box [206] indicating that Oprd1-encoded receptors contribute to lowering anxiety levels and by pharmacological experiments, which revealed that whereas the DOR agonist administration triggers anxiolytic effects [245,246,247,248], DOR antagonists elicit anxiogenic behaviors [248]. The gene discussed is OPRD1; the disease is Anxiety.