Objective To evaluate the effects of Neto1-siRNA on pain-related negative affection and expression of Neto1 (Neuropilin and tolloid-like 1) and NMDA (N-methyl-D-aspartate) receptor NR2A and NR2B subunits in anterior cingulate cortex (ACC) in neuropathic pain (NP) model rats. Methods 40 healthy male Wistar rats were randomly divided into sham operated group (SO group, n=10) and chronic constriction injury of the sciatic nerve group(CCI group, n=10). Twenty-four days after injury LV-Neto1-RNAi (30160-1) was injected in ACC in rats of SO group and CCI group by stereotaxic apparatus to prepare siRNA SO group(n=10) and siRNA CCI group(n=10). The CCI model was established by the chronic constriction injury of the sciatic nerve. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) of each groups were measured on 7th, 14th, 21th and 28th day after operation. The expression of Neto1, NR2A and NR2B subunit mRNA and protein in ACC by RT-PCR and Western Blotting respectively. Results Compared with SO group, TWL and MWT in CCI group were both decreased (P 0.05). In RT-PCR, expression of Neto1, NR2A and NR2B in CCI group was increased compared with SO group (P<0.05), and expression of Neto1 and NR2A was both decreased by Neto1-siRNA (P<0.05), while there was no difference of NR2B. In Western Blotting, expression of Neto1, NR2A and NR2B in CCI group was increased compared with SO group (P<0.05), and expression of Neto1 and NR2A was both decreased by Neto1-siRNA (P<0.05), while there was no difference of NR2B. Conclusion Decreased-expression of Neto1 in ACC may down-regulate NMDA receptor NR2A subunit in NP rats and does not affect pain-related negative affection. Key words: Pain; Anterior cingulate cortex; Conditioned avoidance behavior; Neuropilin and tolloid-like1 Protein; N-methyl-D-aspartate receptor