Inhibition of the Ca2+-Dependent K+ Channel, KCNN4/KCa3.1, Improves Tissue Protection and Locomotor Recovery after Spinal Cord Injury
Inhibition of the Ca2+-Dependent K+ Channel, KCNN4/KCa3.1, Improves Tissue Protection and Locomotor Recovery after Spinal Cord Injury
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DOI：
10.1523/jneurosci.0047-11.2011
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发表时间：
2011-11-09
影响因子：
5.3
通讯作者：
David, Samuel
中科院分区：
文献类型：
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作者：
Bouhy, Delphine;Ghasemlou, Nader;David, Samuel
脊髓损伤 (SCI) 会引发炎症反应，涉及中性粒细胞、巨噬细胞/小胶质细胞和星形胶质细胞以及可能导致继发性组织损伤和功能障碍的分子。在这里，我们评估了钙依赖性 K+ 通道 KCNN4（KCa3.1、IK1、SK4）对成年小鼠下胸段脊髓中度挫伤后继发性损伤的贡献。 SCI 后 1 至 28 天期间监测小鼠脊髓中 KCNN4 mRNA 水平 (RT-PCR)、KCa3.1 蛋白表达 (Western blots) 和细胞表达 (免疫荧光) 的变化。 SCI后KCNN4 mRNA和KCa3.1蛋白迅速升高；双重标记将星形胶质细胞确定为导致这种上调的主要细胞来源。使用 Basso 小鼠量表在旷场测试中评估 28 天的 SCI 后运动功能，通过用选择性 KCa3.1 通道抑制剂 TRAM-34（三芳基甲烷-34）治疗小鼠，以剂量依赖性方式改善了小鼠的运动功能。运动功能的改善伴随着 28 天时组织损失的减少以及神经元和轴突保留的增加。在用TRAM-34治疗挽救组织之前，损伤后12小时脊髓组织中促炎介质、肿瘤坏死因子-α和白细胞介素-1β的表达降低，并且SCI后7天诱导型一氧化氮合酶的表达降低。在体外星形胶质细胞中，TRAM-34 抑制响应代谢型嘌呤能受体刺激的 Ca2+ 信号传导。这些结果表明，阻断 KCa3.1 通道可能是治疗脊髓损伤后继发性损伤的潜在治疗方法。
Spinal cord injury (SCI) triggers inflammatory responses that involve neutrophils, macrophages/microglia and astrocytes and molecules that potentially cause secondary tissue damage and functional impairment. Here, we assessed the contribution of the calcium-dependent K+ channel KCNN4 (KCa3.1, IK1, SK4) to secondary damage after moderate contusion lesions in the lower thoracic spinal cord of adult mice. Changes in KCNN4 mRNA levels (RT-PCR), KCa3.1 protein expression (Western blots), and cellular expression (immunofluorescence) in the mouse spinal cord were monitored between 1 and 28 d after SCI. KCNN4 mRNA and KCa3.1 protein rapidly increased after SCI; double labeling identified astrocytes as the main cellular source accounting for this upregulation. Locomotor function after SCI, evaluated for 28 d in an open-field test using the Basso Mouse Scale, was improved in a dose-dependent manner by treating mice with a selective inhibitor of KCa3.1 channels, TRAM-34 (triarylmethane-34). Improved locomotor function was accompanied by reduced tissue loss at 28 d and increased neuron and axon sparing. The rescue of tissue by TRAM-34 treatment was preceded by reduced expression of the proinflammatory mediators, tumor necrosis factor-alpha and interleukin-1 beta in spinal cord tissue at 12 h after injury, and reduced expression of inducible nitric oxide synthase at 7 d after SCI. In astrocytes in vitro, TRAM-34 inhibited Ca2+ signaling in response to metabotropic purinergic receptor stimulation. These results suggest that blocking the KCa3.1 channel could be a potential therapeutic approach for treating secondary damage after spinal cord injury.