Actions of intrathecal ω-conotoxins CVID, GVIA, MVIIA, and morphine in acute and neuropathic pain in the rat

Abstract

Agents which decrease conductance of N-type voltage-gated Ca2+ channels have been shown to attenuate measures of neuropathic pain in animal models and to provide symptom relief in humans. The ω-conotoxins have demonstrated efficacy but have a low therapeutic index. We have investigated the effects of a new ω-conotoxin, CVID (AM-336), and compared them with ω-conotoxin GVIA (SNX-124), ω-conotoxin MVIIA (SNX-111) and morphine in a spinal nerve ligation model of neuropathic pain in the rat. The ED50 (and 95% CI) for attenuation of tactile allodynia by intrathecal administration for ω-conotoxin CVID, GVIA, MVIIA and morphine was 0.36 (0.27-0.48), 0.12 (0.06-0.24), 0.32 (0.23-0.45) and 4.4 (2.9-6..