Hyperalgesia due to nerve damage: role of nerve growth factor

The hypothesis that nerve growth factor (NGF) and brain-derived neurotrophi c factor (BDNF) contribute to hyperalgesia resulting from nerve damage was tested in rats in which the sciatic nerve was partially transected on one s ide. Administration of antisera raised against NGF and BDNF relieved mechan ical and thermal hyperalgesia in these animals. It has been suggested that NGF may elicit hyperalgesia by inducing mast cells to release algesic agent s such as serotonin (5-HT). We found that degranulation of mast cells with compound 48/80 relieved mechanical and thermal hyperalgesia produced by ner ve damage. We also found that local injection of the 5-HT2A and 5-HT3 recep tor antagonists ketanserin and ICS 205-930 into the affected hind paw relie ved mechanical hyperalgesia in a dose-dependent fashion. These findings sup port the idea that in this rat model of hyperalgesia due to peripheral nerv e damage, NGF acts on mast cells to induce release of 5-HT, which sensitize s nociceptors. Hyperalgesia due to nerve injury and hyperalgesia due to inf lammation may share some common features. (C) 1999 International Associatio n for the Study of Pain. Published by Elsevier Science B.V.