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An in vivo tethered toxin approach for the cell-autonomous inactivation of voltage-gated sodium channel currents in nociceptors

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Smith, ESJ 
Stürzebecher, AS 
Hu, J 
Frahm, S 
Santos-Torres, J 

Abstract

Understanding information flow in sensory pathways requires cell-selective approaches to manipulate the activity of defined neurones. Primary afferent nociceptors, which detect painful stimuli, are enriched in specific voltage-gated sodium channel (VGSC) subtypes. Toxins derived from venomous animals can be used to dissect the contributions of particular ion currents to cell physiology. Here we have used a transgenic approach to target a membrane-tethered isoform of the conotoxin MrVIa (t-MrVIa) only to nociceptive neurones in mice. T-MrVIa transgenic mice show a 44 ± 7% reduction of tetrodotoxin-resistant (TTX-R) VGSC current densities. This inhibition is permanent, reversible and does not result in functional upregulation of TTX-sensitive (TTX-S) VGSCs, voltage-gated calcium channels (VGCCs) or transient receptor potential (TRP) channels present in nociceptive neurones. As a consequence of the reduction of TTX-R VGSC currents, t-MrVIa transgenic mice display decreased inflammatory mechanical hypersensitivity, cold pain insensitivity and reduced firing of cutaneous C-fibres sensitive to noxious cold temperatures. These data validate the use of genetically encoded t-toxins as a powerful tool to manipulate VGSCs in specific cell types within the mammalian nervous system. This novel genetic methodology can be used for circuit mapping and has the key advantage that it enables the dissection of the contribution of specific ionic currents to neuronal function and to behaviour.

Description

Keywords

Animals, Behavior, Animal, Blotting, Southern, Chromosomes, Artificial, Bacterial, Conotoxins, DNA, Electrophysiology, Female, Immunohistochemistry, In Situ Hybridization, Ion Channel Gating, Mice, Mice, Transgenic, Neurons, Afferent, Nociceptors, Oocytes, Pain, Patch-Clamp Techniques, Reverse Transcriptase Polymerase Chain Reaction, Skin, Sodium Channel Blockers, Sodium Channels, Spinal Cord, Xenopus laevis

Journal Title

The Journal of Physiology

Conference Name

Journal ISSN

0022-3751
1469-7793

Volume Title

588

Publisher

Wiley
Sponsorship
This work was supported by grants from the DFG to I.I.-T. and G.R.L. within the collaborative research centre (SFB 665) and from the Alexander von Humboldt Foundation to E.St.J.S.