Establishment Of A Neuropathic Pain Model By The Partial Injury Of Lumbar 5 Dorsal Root In Rats And A Study Of Its Pathophysiological Mechanisms

To study the neural mechanisms of radicular pain, a mechanical allodynia model was established by a partial dorsal rootlets injury (DRI) of left L₅ dorsal root. The behaviour and electrical activities were measured. All DRI rats developed mechanical hypersensitivity as early as first postoperative day, lasting for about 30 days, which was inhibited by surgical or chemical sympathectomy Compared with partial ligation of L₅ spinal nerve (SNI), the neuropathic pain behaviors induced by DRI were weaker than that of SNI, however, the two kind of the models should share with similar mechanisms in developing the mechanical allodynia. The results indicate that a partial ligation of dorsal rootlets induce mechanical allodynia, a kind of behaviour of radicular pain, and sympathetic nerve system might contribute to the generation and maintenance of the allodynia. 21.7% A-fibers recorded in the injured rootlets and 19.0% A-fibers...