Contribution of brain-derived neurotrophic factor to mechanical hyperalgesia induced by ventral root transection in rats

It is generally believed that the development of neuropathic pain primarily results from injuries to sensory afferent fibers. Recent studies found that injuries to the motor efferent fibers (e.g. ventral root transection) also contribute to the development of neuropathic pain. Furthermore, an increase in brain-derived neurotrophic factor (BDNF) synthesis has been found in the ventral root transection model, suggesting a possible role of BDNF in this model. To determine the role of BDNF, we observed the effects of intrathecal antibody against BDNF treatment on ventral root transection-induced mechanical hyperalgesia. Paw withdrawal thresholds to mechanical stimuli were measured before and after surgery. The results showed that ventral root transection in rats produced a significant, lasting decrease of mechanical withdrawal thresholds, presenting the development of mechanical hyperalgesia. Intrathecal antibody against BDNF treatment markedly inhibited ventral root transection-induced mechanical hyperalgesia in a dose-related manner. The findings suggest that BDNF-mediated signaling pathway within spinal cord may be involved in the development of neuropathic pain involving injuries to motor efferent fibers.