Effects of intrathecal ketamine on SNL-induced mechanical allodynia. SNL induced significant mechanical allodynia as shown by von-Frey tests. Intrathecal 300 μg kg-1 ketamine did not change the normal pain threshold of the sham-operated group. Intrathecal ketamine (100 and 300 μg kg-1) showed an effective and reliable anti-allodynia effect in a dose-dependent manner on SNL-induced neuropathic pain, whereas, intrathecally 30 μg kg-1 of ketamine did not influence pain threshold after SNL at all. Drugs were given intrathecally once a day from POD 8 to POD 10. *P < 0.05, compared with that of SNL-Saline group. #
P < 0.05, compared with that of SNL-ketamine 100 μg kg-1 group. There were ten rats in each group. KTM: ketamine.