Neuropathic pain is a chronic pain state caused by nerve injury or diseases. The symptoms involve spontaneous pain, hyperalgesia and allodynia. Neuropathic pain develops by the mechanisms both central nervous system and peripheral nervous system. Moreover,both neuronal cells and glia cells are involved in the development of neuropathic pain. However, the pathogenic mechanism of neuropathic pain is not clearly understood. We previously reported that metallothionein lacked in peripheral nerve from patients of complex regional pain syndrome by proteomic approach. In this report, we examined whether the level of metallothionein (MT) is changed in partial sciatic nerve ligation (PSL) rats as the model animal of neuropathic pain and the administration of metallothionein affects behavior against physical and thermal stimulus to PSL rats. MT-I/II expression was gradually decreased in the distal region of the injury site. At day 28, MT-I/II expression was markedly decreased in both proximal and distal region at the same level. The administration of MT signifi cantly improved allodynia and thermal hyperalgesia comparing to the administration of PBS. Moreover,GAP43, a marker protein of nerve regeneration, increased in the distal region and g lial fibrillar acidic protein, a marker protein of infl ammation, decreased in the proximal region of the injury site. These results suggest that metallothionein is deeply related to occurrence of neuropathic pain and regeneration of the injured nerve in PSL rats.departmental bulletin pape
