Neurotrophins, nociceptors and pain.

Nerve growth factor (NGF) is known to play a key role in the development of hyperalgesia after inflammatory injury. The increased levels of NGF that accompany injury lead to hyperalgesia via peripheral and central spinal mechanisms. New evidence reviewed here indicates that NGF can directly sensitize nociceptive neurones to noxious heat stimuli through rapid modulation of heat/vanilloid receptors or via de-novo increased expression of heat receptors. In addition, new data suggest that the central sensitization that can result from increased NGF may be mediated via central release of another neurotrophin, brain-derived neurotrophic factor.