Mediation of spinal nerve injury induced tactile allodynia by descending facilitatory pathways in the dorsolateral funiculus in rats

MH Ossipov, P Malan Jr, J Lai, F Porreca - Neuroscience letters, 2000 - Elsevier
MH Ossipov, P Malan Jr, J Lai, F Porreca
Neuroscience letters, 2000Elsevier
Evidence exists to indicate that tactile allodynia arising from peripheral nerve injury is
integrated predominately at supraspinal, rather than spinal, sites. In the present
experiments, the possibility that disruption of descending pathways through the dorsolateral
funiculus (DLF) might alter expression of nerve-injury induced tactile allodynia was
explored. Male, Sprague–Dawley rats received L5/L6 spinal nerve ligation (SNL). Lesions to
the DLF were made ipsilateral or contralateral to SNL. Tactile allodynia was determined by …
Evidence exists to indicate that tactile allodynia arising from peripheral nerve injury is integrated predominately at supraspinal, rather than spinal, sites. In the present experiments, the possibility that disruption of descending pathways through the dorsolateral funiculus (DLF) might alter expression of nerve-injury induced tactile allodynia was explored. Male, Sprague–Dawley rats received L5/L6 spinal nerve ligation (SNL). Lesions to the DLF were made ipsilateral or contralateral to SNL. Tactile allodynia was determined by measuring withdrawal thresholds to probing with von Frey filaments. Rats with DLF lesions presented no apparent motor deficits and did not alter sensory threshold in sham-SNL operated rats. DLF lesions made ipsilateral to SNL completely blocked tactile allodynia in SNL rats. Contralateral DLF lesions and sham surgery did not have any effect on SNL-induced allodynia. These results indicate that tactile allodynia after peripheral nerve injury is dependent upon tonic activation of net descending facilitation from supraspinal sites and support the hypothesis of tonic activation of descending facilitation as a basis for chronic pain.
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