This study explores the effects of
oxytocin receptor (OXTR) in the trigeminal ganglion (TG) on orofacial
neuropathic pain. We demonstrate that OXTR activation in the TG relieves the orofacial ectopic
pain as well as inhibits the upregulated expression of
calcitonin gene-related peptide (CGRP), IL-1β, and TNFα in the TG and spinal trigeminal nucleus caudalis (SpVc) of rats with inferior alveolar nerve transection. OXTR, a
G protein-coupled receptor, has been demonstrated to play a significant role in
analgesia after activation by its canonical agonist
oxytocin (OXT) in the dorsal root ganglion. However, the role of OXTR in the trigeminal nervous system on the orofacial
neuropathic pain is still little known. In the present study, we aimed to investigate the regulation effect and mechanism of OXTR in the TG) and SpVc) on orofacial ectopic
pain induced by
trigeminal nerve injury. The inferior alveolar nerve (IAN) was transected to establish a ectopic
pain model. A behavioral test with electronic von Frey filament demonstrated IAN transection (IANX) evoked mechanical
hypersensitivity in the whisker pad from day 1 to at least day 14 after surgery. In addition, administration of OXT (50 and 100 μM) into the TG attenuated the mechanical
hypersensitivity induced by IANX, which was reversed by pretreatment with
L-368,899 (a selective antagonist of OXTR) into the TG. In addition, immunofluorescence showed the expression of OXTR in neurons in the TG and SpVc. Furthermore, Western blot analysis indicated that the upregulated expression of OXTR, CGRP, IL-1β, and TNFα in the TG and SpVc after IANX was inhibited by the administration of OXT into the TG. And the inhibition effect of OXT on the expression of CGRP, IL-1β, and TNFα was abolished by preapplication of OXTR antagonist
L-368,899 into the TG.NEW & NOTEWORTHY This study explores the effects of
oxytocin receptor (OXTR) in the trigeminal ganglion (TG) on orofacial
neuropathic pain. We demonstrate that OXTR activation in the TG relieves the orofacial ectopic
pain as well as inhibits the upregulated expression of
calcitonin gene-related peptide, IL-1β, and TNF-α in the TG and spinal trigeminal nucleus caudalis of rats with inferior alveolar nerve transection.