Activation of the neuronal extracellular signal-regulated kinase 2 in the spinal cord dorsal horn is required for complete Freund's adjuvant-induced pain hypersensitivity.
Activation of the neuronal extracellular signal-regulated kinase 2 in the spinal cord dorsal horn is required for complete Freund's adjuvant-induced pain hypersensitivity.
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DOI：
10.1523/jneurosci.2406-08.2008
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发表时间：
2008-12-24
期刊：
影响因子：
--
通讯作者：
Inturrisi CE
中科院分区：
文献类型：
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作者：
Xu Q;Garraway SM;Weyerbacher AR;Shin SJ;Inturrisi CE
脊髓背角（SCDH）中的细胞外信号调节激酶1和2（ERK 1和ERK 2）信号传导与损伤诱导的疼痛超敏反应有关。现有的ERK通路抑制剂不能区分ERK 1和ERK 2，也不能区别靶向神经元或神经胶质细胞ERK 1/2的表达。我们选择性地抑制ERK 2在成年小鼠SCDH的神经元的表达，通过使用由亲神经腺相关病毒载体递送的ERK 2 siRNA。原位杂交显示siRNA载体诱导的同侧SCDH中ERK 2 mRNA的减少。免疫组化显示神经元磷酸化ERK 1/2（pERK 1/2）减少，Western印迹分析显示siRNA载体降低了ERK 2的表达和磷酸化。相反，基础ERK 1表达不受影响，但pERK 1略有增加。siRNA载体诱导的SCDH中ERK 2表达的敲低不改变基线机械或热缩爪阈值。后爪足底注射完全弗氏佐剂（CFA）在载体对照动物中产生外周炎症、机械性异常性疼痛和热痛觉过敏，其持续至少96小时。它还导致SCDH ERK 1和ERK 2水平在96小时增加，pERK 1和pERK 2水平在1小时和96小时增加。ERK 2 siRNA载体防止ERK 1、ERK 2和pERK 2的变化。此外，siRNA载体在CFA后的整个96小时内保护动物免于发生机械异常性疼痛和热痛觉过敏。这些发现表明，在SCDH神经元中的ERK 2是至关重要的炎性疼痛超敏反应的发展。
Extracellular signal-regulated kinase 1 and 2 (ERK1 and ERK2) signaling in the spinal cord dorsal horn (SCDH) has been implicated in injury-induced pain hypersensitivity. Available ERK pathway inhibitors cannot distinguish between ERK1 and ERK2, nor can they differentially target the expression of neuronal or glial ERK1/2. We selectively inhibited the expression of ERK2 in neurons of the adult mouse SCDH by use of an ERK2 siRNA delivered by a neurotropic adeno-associated viral vector. In situ hybridization revealed a siRNA vector-induced decrease in ERK2 mRNA in the ipsilateral SCDH. Immunohistochemistry showed a decreased neuronal phospho-ERK1/2 (pERK1/2) and Western blot analysis revealed that both ERK2 expression and phosphorylation were reduced by the siRNA vector. In contrast, basal ERK1 expression was not affected, although pERK1 was slightly increased. The siRNA vector-induced knockdown of ERK2 expression in the SCDH did not alter the baseline mechanical or thermal paw withdrawal thresholds. Hindpaw intraplantar injection of Complete Freund’s adjuvant (CFA) produced peripheral inflammation, mechanical allodynia and thermal hyperalgesia in vector control animals that persisted for at least 96 hr. It also caused an increase in SCDH ERK1 and ERK2 levels at 96 hr and pERK1 and pERK2 levels at 1 hr and 96 hr. The ERK2 siRNA vector prevented changes in ERK1, ERK2 and pERK2. In addition, the siRNA vector protected the animals from developing mechanical allodynia and thermal hyperalgesia throughout the 96 hr after CFA. These findings indicate that ERK2 in the SCDH neurons is critical for the development of inflammatory pain hypersensitivity.