Dorsal column lesion reduces mechanical allodynia in the induction, but not the maintenance, phase in spinal hemisected rats

The dorsal column-medial lemniscal (DC-ML) system is known to be a route of ascending input signals for mechanical allodynia following peripheral nerve injury. We examined whether the pain signals after spinal hemisection were transmitted via the DC-ML system in the induction and maintenance phases of the neuropathic pain. Under enflurane anesthesia, rats were subjected to spinal hemisection at T13 level and bilateral DC lesion was made at T8 level 1 day or 3 weeks after the hemisection. The DC lesion 1 day after the hemisection significantly reduced the mechanical, but not cold, allodynia, whereas the DC lesion 3 weeks after the hemisection did not change both mechanical and cold allodynia. These results suggest that the signals for mechanical allodynia following spinal hemisection should be transmitted via the DC-ML system in the induction, but not maintenance, phase. (c) 2005 Elsevier Ireland Ltd. All rights reserved.