Abstract: Objective To investigate the effects of intracerebroventricular injection of neuropeptide S (NPS) on pain and anxiety behaviors in rats with neuropathic pain, and explore the possible mechanism. Methods 40 male Sprague-Dawley rats were randomly divided into Sham-Vehicle group, Sham-NPS group, chronic constriction injury (CCI) group, Neuropeptide S low-dose group (NPSl group, 0.1 nmol/L) and Neuropeptide S high-dose group (NPSh group, 1 nmol/L), with 8 rats in each group. Pain-related behaviors, anxiety-related behaviours,and expression of NPS receptor (NPSR) in the left amygdaloid nucleus were measured on the 14th day via intracerebroventricular injection.Results Compared with the Sham-Vehicle group, the CCI group demonstrated significant pain and anxiety behaviors 14 days after operation (P<0.01), the NPSh group significantly relieved (P<0.01). And there was no significant difference between the NPSl group and the CCI group (P>0.05). Compared with the CCI group, NPSR expression in amygdaloid nucleus increased in the NPSh group. Conclusion NPS can dose-dependently relieve the pain and anxiety behaviors in CCI rats, which may be related with the increase of NPSR in amygdaloid nucleus.

Key words: neuropathic pain, neuropeptide S, anxiety, intracerebroventricular injection, amygdaloid nucleus, rats