capsazepine and Peripheral-Nerve-Injuries

VR1 receptors, present on Adelta- and C-fibres and post-synaptic sites within the spinal cord dorsal horn, is an integrator of noxious stimuli. Here, the contribution of spinal VR1 receptors to spinal nociceptive processing in nerve injured (selective spinal nerve ligated SNL) and sham anaesthetised rats was studied. Spinal capsazepine (0.5-30 microM), a competitive VR1 antagonist, reduced noxious evoked responses of spinal neurones to a greater extent in sham operated rats, compared to SNL rats. Significant differences between the effect of spinal capsazepine on the non-potentiated component of the C-fibre evoked response of SNL and sham operated rats are reported (p< 0.01, two-way ANOVA). Our data suggest there is a functional plasticity of the spinal VR1 receptor following nerve injury.

Topics: Action Potentials; Animals; Capsaicin; Denervation; Dose-Response Relationship, Drug; Down-Regulation; Hyperalgesia; Ligation; Nerve Fibers; Nerve Fibers, Myelinated; Neuralgia; Neuronal Plasticity; Nociceptors; Pain Threshold; Peripheral Nerve Injuries; Peripheral Nerves; Peripheral Nervous System Diseases; Physical Stimulation; Posterior Horn Cells; Rats; Receptors, Drug