SPINAL DORSAL HORN GENE EXPRESSION FOLLOWING LOOSE LIGATION OF THE RAT SCIATIC NERVE

In this study we examined whether the manifestation and loss of thermal hyperalgesia (TH) was associated with a differential pattern of gene expression in the spinal dorsal horn. In animals exhibiting TH 7 days after loose ligation of the sciatic nerve 8 genes were up-regulated and 9 were down-regulated. In contrast, in animals exhibiting loss of TH 28 days after ligation, only 2 genes were up-regulated and 4 were down-regulated. An interesting pattern of gene expression emerged in comparing the two sciatic ligation groups. Four genes were up-regulated during TH and then down-regulated following its loss. Four other genes exhibited the reverse pattern. These data revealed that in animals exhibiting a loss of TH following peripheral nerve injury the pattern of gene expression was similar to that in control, uninjured animals, and that in both of these groups the pattern was different from that of animals' still exhibiting TH. These data lent further support to the notion that genetic plasticity in the spinal dorsal horn may be an important contributor to peripheral nerve injury-elicited neuropathic pain (NP).