Other DOR populations were shown to play a major role in DOR analgesia, in Nav1.8 peripheral neurons in inflammatory and neuropathic pain (Gaveriaux-Ruff et al., 2011; Nozaki et al., 2012) and in forebrain GABAergic neurons in migraine (Dripps et al., 2020). This evidence concerns the gene OPRD1 and migraine disorder.