2. Academic Validation
  3. Nigrostriatal dopaminergic depletion increases static orofacial allodynia

Nigrostriatal dopaminergic depletion increases static orofacial allodynia

  • J Headache Pain. 2016;17:11. doi: 10.1186/s10194-016-0607-z.
Wisam Dieb 1 2 3,  Omar Ouachikh 4,  Sofia Alves 5,  Yves Boucher 6 7,  Franck Durif 8 9,  Aziz Hafidi 10
Affiliations

Affiliations

  • 1 UFR Odontologie, Université Paris Diderot, Paris, France. wisamdieb@yahoo.com.
  • 2 Centre de Psychiatrie et Neurosciences, INSERM U894, Paris, France. wisamdieb@yahoo.com.
  • 3 Clermont Université, Université d'Auvergne, EA7280, Clermont-Ferrand, France. wisamdieb@yahoo.com.
  • 4 Clermont Université, Université d'Auvergne, EA7280, Clermont-Ferrand, France. ouachikh1@yahoo.fr.
  • 5 Clermont Université, Université d'Auvergne, EA7280, Clermont-Ferrand, France. alves.sofia@hotmail.fr.
  • 6 UFR Odontologie, Université Paris Diderot, Paris, France. yves.boucher@univ-paris-diderot.fr.
  • 7 Centre de Psychiatrie et Neurosciences, INSERM U894, Paris, France. yves.boucher@univ-paris-diderot.fr.
  • 8 Clermont Université, Université d'Auvergne, EA7280, Clermont-Ferrand, France. Franck.DURIF@udamail.fr.
  • 9 CHU Clermont-Ferrand, Service de Neurologie, 63000, Clermont-Ferrand, France. Franck.DURIF@udamail.fr.
  • 10 Clermont Université, Université d'Auvergne, EA7280, Clermont-Ferrand, France. azhafidi@univ-bpclermont.fr.
PMID: 26885825 DOI: 10.1186/s10194-016-0607-z
Abstract

Background: This study investigated mesencephalic dopamine depletion effects on static mechanical allodynia (SMA) elicited by chronic constriction of the infraorbitary nerve (CCI-IoN).

Methods: Dopamine depletion (6-OHDA administration into the medial forebrain bundle) effects on CCI-IoN-induced SMA were explored using behavioral (nocifensive behavior score upon non-noxious stimuli using von Frey filament), pharmacological (bromocriptine injections) and immunohistochemical (PKCγ and pERK1/2) techniques.

Results: The central dopamine depletion increased significantly the SMA score. Intraperitoneal and intracisternal injections of bromocriptine alleviated the allodynic behavior observed in both CCI-IoN and CCI-IoN + 6-OHDA animal groups. At the cellular level, dopamine depletion induced a significant increase in PKCγ expression in the medullary dorsal horn (MDH) in rat with CCI-IoN + 6-OHDA when compared to sham Animals (CCI-IoN only). Similarly, after static non-noxious stimuli, the expression of pain marker proteins pERK1/2 within the MDH revealed significantly a higher number of positive cells in CCI-IoN + 6-OHDA rats when compared to the CCI-IoN group.

Conclusion: This study demonstrates that nigrostriatal dopamine depletion exacerbates the neuropathic pain resulting from CCI-IoN. This effect is probably due to an action through descending pain inhibitory systems which increased pain sensitization at the MDH level. It demonstrates also an analgesic effect elicited by D2R activation at the segmental level.

Keywords

Chronic constriction injury; Dopamine; Infraorbitary nerve; Neuropathic pain; Pain; Parkinson disease; Substantia nigra.

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