脊髓蛋白激酶C表达在代谢型谷氨酸受体5参与大鼠吗啡耐受形成中的作用

目的 评价脊髓蛋白激酶C(PKC)表达在代谢型谷氨酸受体5(mGluR5)参与大鼠吗啡耐受形成中的作用.方法 鞘内置管成功的雄性SD大鼠32只,体重180～240 g,随机分为4组(n=8):对照组(C组)、吗啡耐受组(M组)、反义链组(ANT组)和错义链组(MIS组).M组鞘内注射0.9%生理盐水5μl、ANT组和MIC组分别鞘内注射30 nmol反义、错义寡聚脱氧核苷酸(溶于5μl0.9%生理盐水),2次/d,连续8 d,于第6～8天鞘内注射吗啡15μg,2次/d,C组注射等容量生理盐水.于鞘内注射寡聚脱氧核苷酸6、7、8 d(T1～3)时测定大鼠的热痛阈和机械痛阈,第9天(T4)时处死大鼠取L4.5脊髓,采用RT-PCR法测定mGluR5、PKCα、PKCγ的mRNA表达,采用Western blot法测定PKCα、PKCγ的表达.结果 与C组比较,M组和MIS组T1.2时、ANT组T1～3时大鼠热痛阈和机械痛阈升高,T4时M组和MIS组脊髓mGluR5 mRNA、PKCα、PKCγ的表达上调,ANT组脊髓mGluR5 mRNA表达下调(P＜0.05);与M组比较,ANT组T2.3时大鼠热痛阈和机械痛阈升高,脊髓mGluR5 mRNA、PKCα、PKCγ的表达下调(P＜0.05),MIS组上述指标差异无统计学意义(P＞0.05).结论 脊髓PKC表达在mGluR5参与大鼠吗啡耐受形成中起重要作用.

Role of expression of protein kinase C in spinal dorsal horn in metabotropic glutamate receptor 5's participation in development of morphine tolerance in rats

Objective To evaluate the role of the expression of protein kinase Cγ and Cα in spinal dorsal horn in the metabotropic glutamate receptor subtype 5 (mGluR5)'s participation in the development of morphine tolerance in rats. Methods Thirty-two male SD rats in which the intrathecal (IT) catheter was successfully placed were randomly divided into 4 groups (n = 8 each): control group (group C), morphine tolerance group (group M), antisense oligodeoxynucleotide (ODN) plus morphine group (group ANT) and mismatch ODN plus morphine group (group MIS). Rats in group M received 0.9% normal saline (NS) 5 μl twice a day for 8 days, and IT morphine 15 μg was injected simultaneously at 6, 7 and 8 days twice a day. Rats in group ANT and MIS received IT antisense and mismatch ODN 30 nmol (in 0.9% NS 5 μl) twice a day for 8 days respectively and IT morphine 15 μg was injected simultaneously at 6, 7 and 8 days twice a day. Rats in group C received NS instead twice a day for 8 days. Paw-withdrawl threshold (PWT) to thermal and mechanical stimulation was measured at 6, 7 and 8 days after ODN injection (T1-3). The animals were killed on 9th day (T4) and the lumbar segment of the spinal cord was removed for determination of the expression of mGluR5, PKCα and PKCγ mRNA (by RT-PCR), PKCαand PKCγ ( by Western blot). Results PWT to thermal and mechanical stimulation was significantly higher at T1.2in group M and MIS and at T1.3 in group ANT, the expression of mGluR5 mRNA, PKCα and PKCγ was significantly higher at T4 in group M and MIS, and mGluR5 mRNA expression was significantly lower at T4 in group ANT than in group C ( P ＜ 0.05). PWT to thermal and mechanical stimulation was significantly higher at T2.3, while the expression of mGluR5 mRNA, PKCα and PKCγ lower at T4 in group ANT than in group M ( P ＜ 0.05). Conclusion The expression of protein kinase C in spinal dorsal horn plays an important role in the mGluR5's participation in the development of morphine tolerance in rats.