中文摘要：

目的观察小剂量氯胺酮对吗啡耐受褐家鼠肾上腺嗜铬细胞瘤细胞（PC-12）δ阿片受体-1（DOR-1）和N-甲基-D-天冬氨酸受体2B亚单位（NR2B）表达的影响,探讨氯胺酮防止吗啡耐受的相关机制。方法建立PC-12吗啡耐受细胞模型,以时间分辨荧光免疫分析法测定cAMP含量、Re-al-Time PCR技术检测细胞DOR-1和NR2B表达,观察吗啡、氯胺酮及吗啡与氯胺酮联合作用上述指标的变化。结果①10μmol.L-1吗啡作用于PC-12细胞48 h,cAMP含量明显升高,提示成功建立了吗啡耐受细胞模型;②小剂量氯胺酮（0.5μmol.L-1）能防止吗啡耐受发生;③吗啡耐受细胞DOR-1的表达较对照组下降,NR2B的表达较对照组增加。小剂量氯胺酮（0.5μmol.L-1）对DOR-1和NR2B表达无影响,但可逆转吗啡引起的DOR-1表达下调以及NR2B表达上调。结论小剂量氯胺酮可防止吗啡耐受发生,其机制可能与抑制吗啡引起的DOR-1表达下调及NR2B表达上调有关。

英文摘要：

Aim To explore the mechanisms of low-dose ketamine preventing morphine tolerance,and the effect of low dose ketamine on the expression of δ-opioid receptor-1（DOR-1） and N-methl-D-aspartic acid receptor 2B subunit（NR2B） in a cellular model of morphine tolerance.Methods PC-12 cells were treated with morphine,ketamine and both for 48 h.cAMP level,as well as DOR-1 and NR2B expression was measured with time-resolved fluoresence immunoassay and Real-Time PCR,respectively.Results ① After the incubation of 10 μmol·L-1 morphine for 48 hours,the cAMP level in PC-12 cells significantly increased,indicating that the cellular model of morphine tolerance was successfully established.② Low dose ketamine could prevent morphine tolerance.③ The expression of DOR-1 in morphine tolerant PC-12 cells was significantly lower than the control,and NR2B was significantly higher than the control.Low dose ketamine（0.5 μmol·L-1） had no effect on DOR-1 and NR2B expression,but could reverse the morphine-induced down-regulation of DOR-1 and the up-regulation of NR2B.Conclusion Low-dose ketamine can prevent morphine tolerance by inhibiting the down-regulation of DOR-1 and the up-regulation of NR2B in PC-12 cells.