Neuronal-Glial Interactions Maintain Chronic Neuropathic Pain after Spinal Cord Injury

Figure 1

Neuropathic pain behavior and neuronal hyperactivity following SCI. ((a), left) Compared to the sham group (closed circle), the SCI group (open circle) shows complete loss of locomotion at early phase (days 1 to 4) following contusive spinal cord injury (SCI) at the thoracic segment T10. However, three weeks after SCI, animals gradually recover locomotion, showing BBB scores over 7, and are enable to position and withdrawal responses. The BBB scores are averaged by left and right sides of the hindlimbs. ((a), right) Pain behaviors were measured by paw withdrawal thresholds (PTWs), which are determined by quantitative assessment of withdrawal behaviors ([33]). On three weeks after SCI, pain behaviors develop (decrease of PWTs scores) and maintained. (b) On four to five weeks after SCI, lumbar spinal wide dynamic range (WDR) dorsal horn neurons (neurons that respond to all three stimuli: brush, pressure, and pinch in their peripheral receptive field) display significantly increased evoked activity in response to all three stimuli (10 seconds each) compared to the sham group (modified from Gwak et al. [28]). Br: brush, Pr: pressure, and Pi: pinch stimulation. versus the sham group.

(a) Sensorimotor dysfunctions following SCI

(b) Neuronal hyperactivity in spinal dorsal horn