辐照会导致大鼠大脑中促炎环境的区域性特异性改变。
Irradiation induces regionally specific alterations in pro-inflammatory environments in rat brain.
机构信息
School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, Virginia 24061, USA.
出版信息
Int J Radiat Biol. 2010 Feb;86(2):132-44. doi: 10.3109/09553000903419346.
PURPOSE
Pro-inflammatory environments in the brain have been implicated in the onset and progression of neurological disorders. In the present study, we investigate the hypothesis that brain irradiation induces regionally specific alterations in cytokine gene and protein expression.
MATERIALS AND METHODS
Four month old F344 x BN rats received either whole brain irradiation with a single dose of 10 Gy gamma-rays or sham-irradiation, and were maintained for 4, 8, and 24 h following irradiation. The mRNA and protein expression levels of pro-inflammatory mediators were analysed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence staining. To elucidate the molecular mechanisms of irradiation-induced brain inflammation, effects of irradiation on the DNA-binding activity of pro-inflammatory transcription factors were also examined.
RESULTS
A significant and marked up-regulation of mRNA and protein expression of pro-inflammatory mediators, including tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and monocyte chemoattractant protein-1 (MCP-1), was observed in hippocampal and cortical regions isolated from irradiated brain. Cytokine expression was regionally specific since TNF-alpha levels were significantly elevated in cortex compared to hippocampus (57% greater) and IL-1beta levels were elevated in hippocampus compared to cortical samples (126% greater). Increases in cytokine levels also were observed after irradiation of mouse BV-2 microglial cells. A series of electrophoretic mobility shift assays (EMSA) demonstrated that irradiation significantly increased activation of activator protein-1 (AP-1), nuclear factor-kappaB (NF-kappaB), and cAMP response element-binding protein (CREB).
CONCLUSION
The present study demonstrated that whole brain irradiation induces regionally specific pro-inflammatory environments through activation of AP-1, NF-kappaB, and CREB and overexpression of TNF-alpha, IL-1beta, and MCP-1 in rat brain and may contribute to unique pathways for the radiation-induced impairments in tissue function.
目的
大脑中的促炎环境与神经退行性疾病的发生和发展有关。本研究旨在探讨脑照射诱导细胞因子基因和蛋白表达区域性改变的假说。
材料和方法
4 月龄 F344 x BN 大鼠接受单次全脑照射 10 Gy γ射线或假照射，并在照射后 4、8 和 24 小时维持。通过实时逆转录聚合酶链反应（RT-PCR）、酶联免疫吸附试验（ELISA）和免疫荧光染色分析促炎介质的 mRNA 和蛋白表达水平。为了阐明照射诱导脑炎症的分子机制，还研究了照射对促炎转录因子 DNA 结合活性的影响。
结果
从照射脑分离的海马和皮质区观察到促炎介质（包括肿瘤坏死因子-α（TNF-α）、白细胞介素-1β（IL-1β）和单核细胞趋化蛋白-1（MCP-1））的 mRNA 和蛋白表达显著上调。细胞因子表达具有区域性特异性，因为与海马相比，皮质区 TNF-α水平升高（高 57%），而与皮质样本相比，IL-1β水平升高（高 126%）。照射小鼠 BV-2 小胶质细胞后，细胞因子水平也升高。一系列电泳迁移率变动分析（EMSA）表明，照射显著增加了激活蛋白-1（AP-1）、核因子-κB（NF-κB）和 cAMP 反应元件结合蛋白（CREB）的激活。
结论
本研究表明，全脑照射通过激活 AP-1、NF-κB 和 CREB 以及在大鼠脑内过度表达 TNF-α、IL-1β 和 MCP-1，诱导区域性特异性促炎环境，可能导致组织功能辐射损伤的独特途径。
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