Objective: To explore the role of the extracellular signal-regulated kinase (ERK)/cAMP response element binding protein (CREB) pathway in the induction of long-term potentiation (LTP) in the anterior cingulate cortex (ACC) that may be implicated in pain-related negative emotion.
Methods: LTP of field potential was recorded in ACC slice and the expressions of phospho-ERK (pERK) and phospho-CREB (pCREB) were examined using immunohistochemistry method.
Results: LTP could be induced stably in ACC slice by high frequency stimulation (2-train, 100 Hz, 1 s), while APv (an antagonist of NMDA receptor) could block the induction of LTP in the ACC, indicating that LTP in this experiment was NMDA receptor-dependent. Bath application of PD98059 (50 micromol/L), a selective MEK inhibitor, at 30 min before tetanic stimulation could completely block the induction of LTP. Moreover, the protein level of pERK in the ACC was transiently increased after LTP induction, starting at 5 min and returning to basal at 1 h after tetanic stimulation. The protein level of pCREB was also increased after LTP induction. The up-regulation in pERK and pCREB expressions could be blocked by pretreatment of PD98059. Double immunostaining showed that after LTP induction, most pERK was co-localized with pCREB.
Conclusion: NMDA receptor and ERK-CREB pathway are necessary for the induction of LTP in rat ACC and may play important roles in pain emotion.
目的: 探讨细胞外信号激酶(ERK)/cAMP 反应原件蛋白 (CREB) 信号通路对大鼠前扣带皮层神经元长时程增强(LTP) 诱导的影响。
方法: 采用离体脑片场电位记录方法观察ERK激酶抑制剂对大鼠前扣带皮层 (ACC) LTP诱导的影响, 采用免疫组织化学方法观察ACC脑片在强直刺激后不同时间点磷酸化ERK (pERK)和磷酸化CREB (pCREB)的表达情况。
结果: 在大鼠ACC脑薄片上, 高频刺激 (2-train, 100 Hz, 1 s) 能诱导出稳定的场电位 (fEPSP) 长时程增强。 预先给予NMDA 受体竞争性拮抗剂APv (50 µmol/L)可完全阻断LTP 的产生, 提示本实验中ACC 神经元LTP是NMDA受体依赖性的。 灌流液中预先给予MEK抑制剂PD98059 (50 µmol/L)能完全阻断LTP 的产生。 取高频刺激后不同时间点的脑片进行免疫组化检测, 结果显示, 高频刺激后 5 min 时, pERK 表达显著升高, 在10 min 达到最高峰, 1 h 后回复到基础表达水平。 同样, 高频刺激后ACC 脑片中pCREB 的表达也显著增加。 预先灌流液中给予MEK抑制剂PD98059能够阻断高频刺激引起的pERK和pCREB表达上调。 免疫双标结果显示几乎所有的pERK都能与pCREB共定位于同一个神经细胞。
结论: 大鼠前扣带皮层中NMDA受体和ERK/CREB信号通路是长时程增强诱导所必需的。