Summary

Peripheral nerve injury of various types, for example complete nerve transection or loose nerve constrictions (Bennett model), results in changes in expression of a large number of molecules in the parent neuronal cell bodies in the sensory dorsal root ganglia (DRGs), as elegantly amplified in recent global expression analyses. These molecules include neuropeptides, seven-transmembrane G-protein-coupled receptors, ion channels, enzymes, and other types of molecules. Peripheral nerve injuries are often associated with neuropathic pain, and it is an impor-tant task to find out to what extent these changes are pro- or anti-nociceptive. In general terms, it is thought that down-regulation of certain molecules aims to attenuate excitatory (e.g. pain) transmission in the dorsal horn, whereas up-regulated molecules may have trophic effects and promote survival and regeneration, and perhaps also modulate pain transmission. It has been postulated that nerve injury causes sprouting of large-diameter primary afferents from the deep dorsal horn int