Attenuation of Mechanical Hyperalgesia Following Spinal Cord Injury by Administration of Antibodies to Nerve Growth Factor in the Rat

Spinal cord injury (SCI) often leads to central pain syndrome including hyperalgesia to mechanical stimulation. Since there is evidence that nerve growth factor (NGF) contributes to pain-related behaviors, we wished to determine if anti-NGF might inhibit abnormal somatosensory behaviors that develop following SCI in rats. SCI was performed in male Sprague-Dawley rats by T13 spinal hemisection. After spinal hemisection, animals were untreated or treated daily with anti-NGF or saline intraperitoneally for 10 days. In groups of both hemisection only and hemisection with saline treatment, mechanical hyperalgesia developed in both hindlimbs, as evidenced by a decrease in paw withdrawal thresholds. Mechanical responsiveness of wide dynamic range (WDR) neurons on both sides of spinal cord also increased. The anti-NGF treated group demonstrated significant suppression of both mechanical hyperalgesia and increased WDR neuronal responsiveness. These results indicate that anti-NGF prevents the development of abnormal somatosensory behavior and suggest a potential pre-emptive analgesic treatment for central pain.