Differential drug effects on spontaneous and evoked pain behavior in a model of trigeminal neuropathic pain
Authors Deseure K, Hans GH
Received 12 October 2016
Accepted for publication 16 November 2016
Published 27 January 2017 Volume 2017:10 Pages 279—286
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Amy Norman
Peer reviewer comments 3
Editor who approved publication: Dr Michael E Schatman
K Deseure,1 GH Hans2
1Department of Medicine, Laboratory for Pain Research, University of Antwerp, Wilrijk, 2Multidisciplinary Pain Center, Antwerp University Hospital, Edegem, Belgium
Purpose: Baclofen and morphine have shown efficacy against mechanical allodynia after infraorbital nerve chronic constriction injury (IoN-CCI). No drug effects have yet been reported on spontaneous trigeminal neuropathic pain. It has been proposed that the directed face grooming behavior that also develops following IoN-CCI offers a measure of spontaneous trigeminal neuropathic pain.
Subjects and methods: We examined the effects of a continuous 1-week infusion of 30 mg/day carbamazepine (the first-line drug treatment for trigeminal neuralgia), 1.06 mg/day baclofen, 4.18 mg/day clomipramine, and 5 mg/day morphine on spontaneous and mechanically evoked pain behavior (ie, directed face grooming and von Frey testing) in IoN-CCI rats.
Results: Isolated face grooming was significantly reduced in rats receiving carbamazepine and baclofen but not in clomipramine- or morphine-treated rats. All drugs showed significant antiallodynic effects; carbamazepine showed the strongest effects, whereas clomipramine had only minor efficacy.
Conclusion: The tested drugs have differential effects in the IoN-CCI model, and different neuropathological mechanisms may underlie the different somatosensory symptoms in this model. A mechanism-based approach may be needed to treat (trigeminal) neuropathic pain. The present data support IoN-CCI as a model of trigeminal neuralgia in which isolated face grooming is used as a measure of spontaneous neuropathic pain.
Keywords: trigeminal, infraorbital, neuropathic, allodynia, chronic, grooming
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