Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/106091
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Type: Journal article
Title: α-Conotoxin Vc1.1 inhibits human dorsal root ganglion neuroexcitability and mouse colonic nociception via GABAB receptors
Other Titles: alpha-Conotoxin Vc1.1 inhibits human dorsal root ganglion neuroexcitability and mouse colonic nociception via GABAB receptors
Author: Castro, J.
Harrington, A.
Garcia-Caraballo, S.
Maddern, J.
Grundy, L.
Zhang, J.
Page, G.
Miller, P.
Craik, D.
Adams, D.
Brierley, S.
Citation: Gut, 2017; 66(6):1083-1094
Publisher: BMJ Publishing Group
Issue Date: 2017
ISSN: 0017-5749
1468-3288
Statement of
Responsibility: 
Joel Castro, Andrea M Harrington, Sonia Garcia-Caraballo, Jessica Maddern, Luke Grundy, Jingming Zhang, Guy Page, Paul E Miller, David J Craik, David J Adams, Stuart M Brierley
Abstract: Objective: α-Conotoxin Vc1.1 is a small disulfide-bonded peptide from the venom of the marine cone snail Conus victoriae. Vc1.1 has antinociceptive actions in animal models of neuropathic pain, but its applicability to inhibiting human dorsal root ganglion (DRG) neuroexcitability and reducing chronic visceral pain (CVP) is unknown. Design: We determined the inhibitory actions of Vc1.1 on human DRG neurons and on mouse colonic sensory afferents in healthy and chronic visceral hypersensitivity (CVH) states. In mice, visceral nociception was assessed by neuronal activation within the spinal cord in response to noxious colorectal distension (CRD). Quantitative-reverse-transcription-PCR, single-cell-reverse-transcription-PCR and immunohistochemistry determined γ-aminobutyric acid receptor B (GABABR) and voltage-gated calcium channel (CaV2.2, CaV2.3) expression in human and mouse DRG neurons. Results: Vc1.1 reduced the excitability of human DRG neurons, whereas a synthetic Vc1.1 analogue that is inactive at GABABR did not. Human DRG neurons expressed GABABR and its downstream effector channels CaV2.2 and CaV2.3. Mouse colonic DRG neurons exhibited high GABABR, CaV2.2 and CaV2.3 expression, with upregulation of the CaV2.2 exon-37a variant during CVH. Vc1.1 inhibited mouse colonic afferents ex vivo and nociceptive signalling of noxious CRD into the spinal cord in vivo, with greatest efficacy observed during CVH. A selective GABABR antagonist prevented Vc1.1-induced inhibition, whereas blocking both CaV2.2 and CaV2.3 caused inhibition comparable with Vc1.1 alone. Conclusions Vc1.1-mediated activation of GABABR is a novel mechanism for reducing the excitability of human DRG neurons. Vc1.1-induced activation of GABABR on the peripheral endings of colonic afferents reduces nociceptive signalling. The enhanced antinociceptive actions of Vc1.1 during CVH suggest it is a novel candidate for the treatment for CVP.
Keywords: Abdominal pain
Description: Published Online First 17 February 2016
Rights: Published by the BMJ Publishing Group Limited. This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/ licenses/by-nc/4.0/
RMID: 0030043866
DOI: 10.1136/gutjnl-2015-310971
Grant ID: http://purl.org/au-research/grants/nhmrc/1049928
Appears in Collections:Medicine publications

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