Original article: INDUCTION OF SPINAL LONG-TERM SYNAPTIC POTENTIATION IS SENSITIVE TO INHIBITION OF NEURONAL NOS IN L5 SPINAL NERVE-TRANSECTED RATS

The role of neuronal nitric oxide synthase (nNOS) in the central mechanism of neuropathic pain and long-term potentiation (LTP) of peripheral afferents remains obscure. The current study investigated the effect of intrathecal application of 7-nitroindazole (7-NI), a selective nNOS inhibitor (8.15 µg/5µl), on mechanical allodynia on day 14 after L5 spinal nerve tran-section. Furthermore, using in vivo single unit extracellular recording, we examined the effect of 7-NI on the induction of LTP of Aδ- and C-fiber-evoked responses. We have demonstrated that 7-NI attenuates nerve-injury-evoked mechanical allodynia. Additionally, our electrophy-siological study has shown that the spinal administration of 7-NI significantly inhibits the in-duction of the LTP of Aδ- and C-fiber-evoked responses on day 14 after neuropathy. These data suggest that activation of nNOS may be crucial for the induction of the spinal LTP of Aδ- and C-fiber-evoked responses following peripheral nerve damage