Abstract: AIM: To investigate the efficacy of domestic Ziconotide in treating neuropathic pain induced by L5 spinal nerve ligation in rats.METHODS: Forty male SD rats (weighted from180 to 220 g) were randomly divided into five groups, including sham control group(Group SC): 0.9%NS 20 μL; L5SNL model control group (Group L5SNL): 0.9%NS 20 μL; DZ1 group: the first batch of domestic ziconotide 100 ng; DZ2 group: the second batch of domestic ziconotide 100 ng; IZ group: imported ziconotide 100 ng. The changes of the mechanical pain threshold and thermal pain threshold in these rats by testing their 50% paw withdrawal threshold(50%PWT) and thermal withdrawal duration(TWD) pain threshold in these rats were observed, and the maximum possible effect (MPE) was calculated to evaluate the analgetic efficacy of domestic and imported ziconotide in relieving the neuropathic pain.RESULTS: Compared with the model group, both 50%PWT and TWD were significantly increased by intrathecal injection 100 ng of domestic Ziconotide and imported one respectively(P＜0.01); There were no significant differences in the maximum possible effect(MPE) of inhibiting the mechanical pain and TWD between the domestic Ziconotide group and imported one.CONCLUSION: Domestic Ziconotide has a significant effect on the neuropathic pain induced by L5 spinal nerve ligation in rats.

Key words: Ziconotide, Neuropathic pain, 50% paw withdrawal threshold, Thermal withdrawal duration, The maximum possible effect