ERKⅠ/Ⅱ在脊髓背角LTP的诱导和维持中的作用

目的：探讨胞外信号调节激酶（ERKⅠ/Ⅱ）在大鼠脊髓背角C-纤维诱发电位长时程增强（LTP）的诱导和维持中的作用。 方法： 细胞外记录技术在脊髓腰膨大部记录背角浅层神经元C-纤维诱发电位。 结果： (1) MEK的选择性抑制剂PD98059（100 μmol/L）或SL327 (200 μmol/L) 对脊髓背角C-纤维诱发电位的基础电位没有影响，但可阻断脊髓背角LTP的诱导。(2) PD98059或SL327呈时间依赖性逆转脊髓背角LTP。在LTP 诱导后15 min，脊髓局部给予PD98059（100 μmol/L）或SL327(200 μmol/L)可完全逆转LTP。在LTP 诱导后30 min，单独给予PD98059或SL327，LTP的抑制率分别为62.5％与75.0％。但同样浓度的PD98059或SL327在LTP 诱导后1 h，均不能逆转业已建立的LTP。 结论： 脊髓背角ERKⅠ/Ⅱ的激活参与C-纤维诱发电位LTP的诱导和早期维持。

Role of ERK Ⅰ/Ⅱ in the induction and maintenance of the spinal LTP

AIM: The role of external-signal regulated kinaseⅠ/Ⅱ(ERKⅠ/Ⅱ) in the induction and maintenance of spinal long-term potentiation (LTP) is evaluated.METHODS: The C-fiber evoked field potentials were recorded at the superficial layers of spinal dorsal horn at the lumbar enlargement.RESULTS: (1) PD98059 (100 μmol/L) or SL327 (200 μmol/L), a selective MEK inhibitor, completely blocked LTP induction when applied at 30 min prior to tetanic stimulation.(2) PD98059 or SL327 reversed spinal LTP in a time-dependent manner.At 15 min after LTP induction, PD98059 (100 μmol/L) or SL327 (200 μmol/L) reversed LTP completely, and at 30 min after LTP induction, the inhibitory rate of spinal LTP inhibited by PD98059 or SL327 was 62.5% and 75.0%， respectively.At 1 h after LTP induction, however, the same concentration of PD98059 or SL327 did not affect the spinal LTP.CONCLUSION: Activation of ERKⅠ/Ⅱ in spinal dorsal horn may be crucial for the induction and the early-phase maintenance of LTP of C-fiber evoked field potentials.