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Pain Management 2019 & Internal Medicine 2019
International Journal of Anesthesiology & Pain Medicine
ISSN: 2471-982X
Page 55
JOINT EVENT
7
th
Edition of International Conference on
Pain Management
8
th
Edition of International Conference on
Internal Medicine &
Patient Care
&
March 25-26, 2019
Rome, Italy
Int J Anesth Pain Med 2019, Volume 5
DOI: 10.21767/2471-982X-C1-006
Targeting descending dopaminergic signalling to treat
trigeminal neuropathic pain
Feng Tao
Texas A&M University College of Dentistry, USA
T
rigeminal neuropathic pain is a debilitating condition
and represents a challenge to clinicians. In the
present study, we employed optogenetic manipulation
to investigate the role of the dopaminergic pathway from
hypothalamic A11 nucleus to spinal trigeminal nucleus
caudalis (Sp5C) in orofacial neuropathic pain. Dopamine
receptor D1-Cre and D2-Cre male mice were used in this
study. Achronic constriction injury-infraorbital nerve (CCI-
ION) mousemodel was prepared as described previously.
Optogenetic manipulation was conducted to examine
the effect of activation or inhibition of D1/2-mediated
dopaminergic signaling on trigeminal neuropathic pain
in the CCI-ION model. Conditional place preference
(CPP) and von Frey filaments were used to measure
the emotional and sensory components of the CCI-ION-
induced pain behaviors. Immunohistochemistry staining
was used to assess the expression of D1/2 dopamine
receptor and A11 lesion. Pain behavioral testing showed
that D1-Cre mice injected with the inhibitory virus AAV5-
EF1a-DIO-eNpHR3.0-EYFP exhibited a decrease in pain
behaviors when stimulated with green light (532 nm),
but D1-Cre mice injected with the excitatory virus AAV5-
EF1a-DIO-ChR2 (E123A)-EYFP exhibited an increase in
pain behaviors when stimulated with blue light (473 nm).
Interestingly, we observed an opposite effects in D2-
Cre mice when the same optogenetic manipulation was
carriedout.Moreover, 6-hydroxy-dopaminehydrobromide
(6-OHDA)-produced specific lesion of A11 dopaminergic
neurons blocked the effect of optogenetic manipulation
of the Sp5C D1/2 dopamine receptor on trigeminal
neuropathic pain in this CCI-ION model. In addition, D1
and D2 dopamine receptors were highly expressed in
the Sp5C. Therefore, the descending dopaminergic
pathway from A11 to Sp5C could be a critical target for
the treatment of trigeminal neuropathic pain.
tao@tamhsc.edu