α(2) noradrenergic receptor suppressed CaMKII signaling in spinal dorsal horn of mice with inflammatory pain.
α(2) noradrenergic receptor suppressed CaMKII signaling in spinal dorsal horn of mice with inflammatory pain.
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DOI：
10.1016/j.ejphar.2013.12.026
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发表时间：
2014-02
影响因子：
5
通讯作者：
Xin-Tai Wang;Xia Lian;Ying-Ming Xu;Zhanwei Suo;Xian Yang;Xiao-Dong Hu
中科院分区：
文献类型：
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作者：
Xin-Tai Wang;Xia Lian;Ying-Ming Xu;Zhanwei Suo;Xian Yang;Xiao-Dong Hu
鞘内应用α2去甲肾上腺素受体激动剂可有效缓解周围组织损伤引起的病理性疼痛。然而，α2去甲肾上腺素受体的脊髓镇痛机制仍有待表征。本研究通过免疫组织化学和蛋白质印迹来阐明小鼠脊髓背角α2去甲肾上腺素能受体启动的信号通路，并确定钙/钙调蛋白依赖性蛋白激酶II（CaMKII）是去甲肾上腺素能抑制炎性疼痛的重要靶点。我们的数据显示，足底注射弗氏完全佐剂（CFA）显着增强了 CaMKII 在苏氨酸 286 处的自磷酸化，而鞘内注射 α2 去甲肾上腺素受体激动剂可乐定可以消除这种情况。 Gi 蛋白偶联 α2 去甲肾上腺素受体可能抑制 cAMP 依赖性蛋白激酶 (PKA)，从而干扰 CaMKII 信号传导。我们发现，在完整小鼠中，PKA 的药理学激活也增强了脊髓 CaMKII 自磷酸化水平，而可乐定完全拮抗这一水平。此外，注射 CFA 的小鼠中直接 PKA 抑制模拟了 α2 去甲肾上腺素受体对 CaMKII 的抑制作用。 PKA 抑制已被证明可以通过增强蛋白磷酸酶活性来下调 CaMKII。与这一观点一致，在注射 CFA 的小鼠中，用蛋白磷酸酶抑制剂冈田酸进行脊柱治疗排除了可乐定介导的 CaMKII 去磷酸化。通过 PKA/蛋白磷酸酶/CaMKII 途径，可乐定显着降低 CFA 诱发的 N-甲基-d-天冬氨酸亚型谷氨酸受体 GluN1 和 GluN2B 亚基以及 α-氨基-3-羟基-5-甲基异恶唑-4-丙酸亚型谷氨酸受体 GluA1 亚基的磷酸化。这些数据表明，干扰 CaMKII 信号传导可能代表去甲肾上腺素能抑制炎性疼痛的重要机制。
Intrathecal application of α2noradrenergic receptor agonists effectively alleviates the pathological pain induced by peripheral tissue injury. However, the spinal antinociceptive mechanisms of α2noradrenergic receptors remain to be characterized. The present study performed immunohistochemistry and western blot to elucidate the signaling pathway initiated by α2noradrenergic receptors in spinal dorsal horn of mice, and identified calcium/calmodulin-dependent protein kinase II (CaMKII) as an important target for noradrenergic suppression of inflammatory pain. Our data showed that intraplantar injection of Complete Freund's Adjuvant (CFA) substantially enhanced CaMKII autophosphorylation at Threonine 286, which could be abolished by intrathecal administration of α2noradrenergic receptor agonist clonidine. Gi protein-coupled α2noradrenergic receptor might inhibit cAMP-dependent protein kinase (PKA) to disturb CaMKII signaling. We found that pharmacological activation of PKA in intact mice also enhanced spinal CaMKII autophosphorylation level, which was completely antagonized by clonidine. Moreover, direct PKA inhibition in CFA-injected mice mimicked the suppressive effect of α2noradrenergic receptors on CaMKII. PKA inhibition has been shown to downregulate CaMKII by enhancing protein phosphatase activity. Consistent with this notion, spinal treatment with protein phosphatase inhibitor okadaic acid ruled out clonidine-mediated CaMKII dephosphorylation in CFA-injected mice. Through PKA/protein phosphatase/CaMKII pathway, clonidine noticeably decreased CFA-evoked phosphorylation of N-methyl-d-aspartate subtype glutamate receptor GluN1 and GluN2B subunit as well as α-amino-3-hydroxy-5-methylisoxazole-4-propionic Acid subtype glutamate receptor GluA1 subunit. These data suggested that interference with CaMKII signaling might represent an important mechanism underlying noradrenergic suppression of inflammatory pain.