Abstract： Objective To observe the changes of expression levels of NMDA receptor NR2A and NR2B in anterior cingulate cortex (ACC) of chronic pancreatitis (CP) rats and explore its roles in the pathogenesis of pain in CP.Methods Male adult SD rats were randomly divided into CP group,control group and normal group using random number method.CP rat model was established by injecting 8mg/kg dibutyltin dichloride (DBTC) through tail vein.Control group was injected with a equal volume mixture of ethanol and glycerol via tail vein.After 4 weeks,yon Frey hair of different sizes (3.85,5.50,7.05,10.4,17.8 g) were used to stimulate the abdomen of the rats and the percentage of the positive pain response was recorded.Then the rats were sacrificed.The pancreas was collected for pathological examination.NR2A and NR2B subunit mRNA and protein expression in ACC was detected by realtime-PCR and Western Blotting,respectively.Results The success rate of CP model establishment was 60％.As Van Frey hair used to stimulate the rat abdomen increased from 3.85 g to 17.8 g,the percentage of positive pain response increased from (38.33 ±7.53)％ to(73.33±8.17)％ in CP group,from (7.80±6.70)％ to (34.44±5.27)％ in control group,from(6.57±5.48) ％ to(33.33 ± 5.00) ％ in normal group,which was increased with the increase of the stimulation intensity.For each stimulation intensity,the percentage of positive pain response in CP group was all obviously higher than those in control and normal group,and the differences were all statistically significant (all P ＜ 0.01),but there was no statistical difference between control group and normal group.The protein expression of NR2A of ACC in CP group,control group and normal group was 1.25 ± 0.78,0.95 ± 0.14 and 0.91 ± 0.09,respectively.The protein of NR2B in three groups were 1.44 ± 0.12,0.93 ± 0.08 and 0.94 ±0.04,respectively.NR2A and NR2B protein expressions in the CP group were both significantly higher than those in control group and normal group,and the difference was statistically significant (P＜0.01).The mRNA expression of NR2A in three groups were 1.43 ± 0.20,0.80 ± 0.10 and 1.01 ± 0.13,respectively.The mRNA expression of NR2B in three groups were 1.40 ± 0.09,0.98 ± 0.14 and 0.94 ± 0.05,respectively.The mRNA expressions of NR2A and NR2B in CP group were significantly higher than those in normal and control group,and the difference was statistically significant (P ＜0.01).Conclusions The expression of glutamate receptor NR2A and NR2B in ACC were upregulated in CP rats and may be involved in the development of the pain.