Gene Therapy for Chronic Pain: How to Manipulate and Unravel Pain Control Circuits from the Brain? - Gene Delivery and Therapy for Neurological Disorders - page 338

a bidirectional infl uence on nociception (inhibition and facilitation)
by specifi c subpopulations of noradrenergic neurons [ 28 ]. At the
DRt, the use of the retrogradely transported HSV-1 vector
described here along with cell-specifi c promoters to target the
optogenetic activation or inhibition of other DRt afferents will
allow continuing the characterization of DRt-modulatory path-
ways. Since a large amount of DRt afferents are located in the
cortex [ 29 ] and, as recently reviewed [ 30 ], the translational value
of optogenetic manipulation of cortical neurons is putatively
higher, new avenues for unraveling descending pain modulation
from the DRt emerge.
The genetic approach described in this chapter complemented
in future studies with optogenetics will allow to better characterize
pain control circuits in the brain and ultimately provide the sub-
strate toward redefi ning gene therapy strategies directed to the
brain in the context of widespread chronic pain, such as fi bromyal-
gia or complex regional pain syndrome.

Acknowledgments

The current research was supported by FCT Project PTDC/SAU-
NSC/110954/2009 and FCOMP-01-0124-FEDER-015900.

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