Key Laboratory of Medical Protection for Electromagnetic Radiation, Ministry of Education, Third Military Medical University , Chongqing, 400038 , P. R. China.
Int J Radiat Biol. 2013 Nov;89(11):976-84. doi: 10.3109/09553002.2013.817699. Epub 2013 Jul 29.
Several studies suggest that radiofrequency electromagnetic field (RF-EMF) exposure can induce neuronal injury. The aim of the present work was to investigate whether the cyclin-dependent kinase 5 (CDK5) pathway is involved in neuronal injury induced by RF-EMF exposure.
Newborn Sprague-Dawley rats' primary cultured cortical neurons were exposed to pulsed 2.45 GHz RF-EMF for 10 min. The cellular viability was assessed using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The apoptosis was assessed by Hoechst 33342 and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling co-staining. The protein expressions of CDK5, p35, p25, and phosphorylated tau at Ser(404) were examined by Western blot analysis. The CDK5 activity was detected using a histone-H1 kinase assay.
The cellular viability of neurons was significantly decreased (p < 0.01, Partial Eta Squared [ηp(2)]: 0.554), and the percentage of apoptotic nuclei (p < 0.01, ηp(2) = 0.689), activity of CDK5 (p < 0.05, ηp(2) = 0.589), ratio of p25 and p35 (p < 0.05, ηp(2 =) 0.670), levels of tau phosphorylation at Ser(404) (p < 0.01, ηp(2) = 0.896) were significantly increased after RF-EMF exposure. No significant change was detected in CDK5 expression after RF-EMF exposure. Pretreatment with Roscovitine (a CDK5 inhibitor) significantly blocked the RF-EMF-induced decrease of cellular viability (p < 0.05, ηp(2) = 0.398) and tau hyperphosphorylation at Ser(404) (p < 0.01, ηp(2 =) 0.917), but did not significantly block the RF-EMF-induced apoptosis (p > 0.05, ηp(2) = 0.130).
These results suggest that abnormal activity of p25/CDK5 is partially involved in primary cultured cortical neuron injury induced by RF-EMF exposure.
几项研究表明，射频电磁场（RF-EMF）暴露会引起神经元损伤。本研究旨在探讨细胞周期蛋白依赖性激酶 5（CDK5）通路是否参与 RF-EMF 暴露诱导的神经元损伤。
将新生 Sprague-Dawley 大鼠原代皮质神经元暴露于脉冲 2.45GHz RF-EMF 中 10 分钟。使用 3-（4,5-二甲基噻唑-2-基）-2,5-二苯基四氮唑溴化物测定法评估细胞活力。通过 Hoechst 33342 和末端脱氧核苷酸转移酶（TdT）介导的 dUTP 缺口末端标记共染色评估细胞凋亡。通过 Western blot 分析检测 CDK5、p35、p25 和磷酸化 tau 丝氨酸 404 处的蛋白表达。使用组蛋白 H1 激酶测定法检测 CDK5 活性。
神经元的细胞活力明显降低（p < 0.01，部分 eta 平方[ηp(2)]：0.554），核凋亡百分比（p < 0.01，ηp(2) = 0.689），CDK5 活性（p < 0.05，ηp(2) = 0.589），p25 和 p35 的比例（p < 0.05，ηp(2 =) 0.670），tau 丝氨酸 404 处磷酸化水平（p < 0.01，ηp(2) = 0.896）在 RF-EMF 暴露后显著增加。RF-EMF 暴露后 CDK5 表达无明显变化。用 Roscovitine（CDK5 抑制剂）预处理可显著阻断 RF-EMF 诱导的细胞活力降低（p < 0.05，ηp(2) = 0.398）和 tau 丝氨酸 404 处过度磷酸化（p < 0.01，ηp(2 =) 0.917），但不能显著阻断 RF-EMF 诱导的细胞凋亡（p > 0.05，ηp(2) = 0.130）。
这些结果表明，p25/CDK5 的异常活性部分参与了 RF-EMF 暴露诱导的原代皮质神经元损伤。
