Chen Weiqiang, Sheng Jiangtao, Guo Jingfang, Peng Guoyi, Hong Jinfang, Li Bingbing, Chen Xiaoxuan, Li Kangsheng, Wang Shousen
Department of Neurosurgery, Fuzhou General Hospital, Xiamen University Medical College, 156 North Road, West Second Ring, Fuzhou, 350025, Fujian, China.
Department of Neurosurgery, First Affiliated Hospital, Shantou University Medical College, 57 Changping Road, Shantou, 515041, Guangdong, China.
J Neuroinflammation. 2017 Mar 31;14(1):73. doi: 10.1186/s12974-017-0847-0.
Traumatic brain injury (TBI) triggers both immediate (primary) and long-term (secondary) tissue damages. Secondary damages can last from hours to days or even a lifetime. Secondary damages implicate several mechanisms, including influence of inflammatory mediators, mainly cytokines, on excitability of ion channels. However, studies should further explore the effects of inflammatory cytokines on voltage-gated sodium channels (VGSCs) and excitability in distal intact neurons.
Mixed cultures of mouse cortical astrocytes and neurons were subjected to mechanical injury (trauma) to mimic TBI in vitro. Expression of various cytokines in these cultures were measured by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. A trauma-conditioned medium with or without brain-derived neurotrophic factor (BDNF) was added to mouse primary cortical neurons for 6 and 24 h to mimic combined effects of multiple inflammatory cytokines on VGSCs. Spike behaviors of distal intact neurons were examined by whole-cell patch-clamp recordings.
Mechanical injury in mixed cortical neuron-astrocyte cultures significantly increased expression levels of multiple cytokines, including interleukin (IL)-1β, IL-6, tumor necrosis factor-α, monocyte chemoattractant protein-1, chemokine (C-C motif) ligand-5, IL-10, and transforming growth factor-β1, at 6 and 24 h after injury. Incubation in trauma-conditioned medium increased functional VGSCs in neuronal membranes and Na currents. Enhanced VGSCs were almost completely abolished by BDNF, and reinforcement of Na currents was also reduced in a dose-dependent manner. BDNF (30 ng/mL) also significantly reversed reduced neuronal cell viability, which was induced by medium conditioned at 6 h. At 6 and 24 h, trauma-conditioned medium significantly increased spike frequency but not spike threshold.
In TBI, the combined effect of inflammatory cytokines is directly involved in VGSC, Na current, and excitability dysfunction in distal intact neurons. BDNF may partly exert neuroprotective effects by maintaining balance of VGSC function in distal intact neurons.
创伤性脑损伤（TBI）会引发即时（原发性）和长期（继发性）组织损伤。继发性损伤可持续数小时至数天甚至终生。继发性损伤涉及多种机制，包括炎症介质（主要是细胞因子）对离子通道兴奋性的影响。然而，研究应进一步探索炎症细胞因子对电压门控钠通道（VGSCs）以及远端完整神经元兴奋性的影响。
对小鼠皮质星形胶质细胞和神经元的混合培养物进行机械损伤（创伤），以在体外模拟TBI。通过实时聚合酶链反应和酶联免疫吸附测定法测量这些培养物中各种细胞因子的表达。将含有或不含有脑源性神经营养因子（BDNF）的创伤条件培养基添加到小鼠原代皮质神经元中6小时和24小时，以模拟多种炎症细胞因子对VGSCs的联合作用。通过全细胞膜片钳记录检查远端完整神经元的放电行为。
混合皮质神经元 - 星形胶质细胞培养物中的机械损伤在损伤后6小时和24小时显著增加了多种细胞因子的表达水平，包括白细胞介素（IL）-1β、IL-6、肿瘤坏死因子-α、单核细胞趋化蛋白-1、趋化因子（C-C基序）配体-5、IL-10和转化生长因子-β1。在创伤条件培养基中孵育增加了神经元膜中的功能性VGSCs和钠电流。BDNF几乎完全消除了增强的VGSCs，并且钠电流的增强也以剂量依赖性方式降低。BDNF（30 ng/mL）还显著逆转了由6小时条件培养基诱导的神经元细胞活力降低。在6小时和24小时时，创伤条件培养基显著增加了放电频率，但未增加放电阈值。
在TBI中，炎症细胞因子的联合作用直接参与远端完整神经元中的VGSC、钠电流和兴奋性功能障碍。BDNF可能通过维持远端完整神经元中VGSC功能的平衡部分发挥神经保护作用。
