Effect of intrathecal injection of neuropeptide S and gabapentin on pain and anxiety behavior in rats with neuropathic pain

Objective To investigate the effects of intrathecal injection of Neuropeptide S and Gabapentin on pain behavior and anxiety behavior in rats with neuropathic pain,and to explore the possible mechanisms of of N-methyl-D-aspartic acid(NMDA) receptor 1.Methods Seventy-two male Sprague-Dawley (SD) rats,which were successfully deployed intrathecal catheter,were randomly divided into six groups (n=12),including sham group,CCI group,neuropeptide S low-dose group (NPSl group),neuropeptide S high-dose group (NPSh group),gabapentin low dose group (Gbl group) and gabapentin high dose group(Gbh group).Pain-related behaviors,depression-related behaviors,and expression of NMDA receptor1 in the dorsal horn of the spinal cord were measured at 14 d after 7 d via intrathecal injection.Results Compared with the sham group,the rats suffering CCI demonstrated significant pain and anxiety behavior (P＜0.01).High dose NPS and each dose gabapentin (but not low dose NPS) can significantly reduce mechanical withdrawal threshold (MWT) [(2.7±1.3) g vs (4.5±1.7),(5.4±1.0),(8.1±3.6) g]and thermal hyperalgesia foot withdrawal lantency(FWL) [(3.9±0.6) s vs (5.8± 1.5),(6.3± 1.2),(7.6± 1.6) s] compared with CCI group(P＜0.05).In the EPM test,compared with CCI group,only high dose NPS significantly extended numbers entries into the open arms (6.3±1.6 vs 2.9±1.5)(P＜0.05) and time spent in the open arms(22.4±4.3)％ vs (10.9±2.7)％(P＜0.05).In the open field test,each dose NPS and gabapentin added the proportion of central Zone cross (P＜0.05) and time spent (P＜0.05).Immunofluorescence and western blot experiments showed that,regardless of the level measurement group,both drugs can suppress the increase NR1 receptor expression in the dorsal horn of the spinal cord,and has a statistical significance.Conclusions Neuropeptide S and gabapentin dosedependent pain and anxiety behavior reversal CCI rats,which may be related NMDA receptor pathway. Key words: Neuropeptide S;  Gabapentin;  Neuropathic Pain;  Anxiety;  Intrathecal injection