电离辐射激活前额叶皮质NLRP3炎性小体诱导小鼠认知功能障碍

摘要

探讨电离辐射诱导小鼠认知功能障碍的可能机制.20只雌性昆明小鼠随机分为对照组和辐照组,辐照组小鼠接受137Cs γ射线单次全身辐照至吸收剂量4 Gy.35 d后采用新旧事物识别实验检测小鼠认知功能;免疫组织化学法检测小鼠前额叶皮质区小胶质细胞标记物离子钙接头蛋白-1(IBA-1)的表达;蛋白质印迹法检测前额叶皮质区核苷酸结合寡聚化结构域样受体蛋白3(NLRP3)、凋亡相关斑点样蛋白(ASC)、半胱氨酸天门冬氨酸蛋白酶-1(Caspase-1)、白细胞介素-1β(IL-1 β)和白细胞介素-18(IL-18)蛋白的表达变化;荧光定量PCR(RT-PCR)检测前额叶皮质IBA-1、NLRP3、ASC和Caspase-1 mRNA的表达情况.结果显示:与对照组相比,辐照组小鼠在新旧事物识别实验中对新事物的分辨率明显降低(38.39 ± 3.69 vs. 28.82 ± 2.08, p<0.05);前额叶皮质区IBA-1阳性细胞数(138.2 ± 3.7 vs. 159.6 ± 6.9, p<0.05)和mRNA表达(1.000 ± 0.031 vs. 1.173 ± 0.055, p<0.05)均显著上调;前额叶皮质区NLRP3、ASC、Caspase-1蛋白(1.000 ± 0.066 vs. 1.341 ± 0.119, p<0.05;1.000 ± 0.073 vs. 1.298 ± 0.083, p<0.05;1.000 ± 0.039 vs. 1.603 ± 0.159, p<0.01)及NLRP3、 ASC mRNA表达(1.000 ± 0.046 vs. 1.372 ± 0.071, p<0.01; 1.000 ± 0.068 vs. 1.225 ± 0.069, p<0.05)均明显上调;前额叶皮质区炎性细胞因子IL-1β和IL-18的表达(1.000 ± 0.033 vs. 1.167 ± 0.059, p<0.05;1.000 ± 0.196 vs. 1.614 ± 0.163, p<0.05)均明显上调.结果提示,电离辐射可能是通过激活前额叶皮质区小胶质细胞,活化NLRP3炎性小体,诱导炎症因子释放引起认知功能障碍的.%ABSTRACT To explore the potential mechanism of cognitive impairment induced by ionizing radiation,twenty Kunming female mice were randomly divided into control group and irradiation group. The mice in the irradiation group received a single whole body irradiation of 137Cs γ-rays at an absorbed dose of 4 Gy. The novel object recognition test was used to evaluate the cognitive function of mice 35 d after irradiation. The expression of the microglial marker ionized calcium binding adapter molecule-1 (IBA-1) in the prefrontal cortex was determined by immunohistochemical staining. Western blot was used to detect the expression of nucleotide-binding oligomerization domain such as receptor protein 3 (NLRP3), apoptosis-associated speck-like protein (ASC), cysteinyl aspartate specific proteinase-1 (Caspase-1), interleukin (IL)-1β, and IL-18 protein in the prefrontal cortex. The expression of IBA-1, NLRP3, ASC, and Caspase-1 mRNA in the prefrontal cortex was determined by reverse transcription polymerase chain reaction. The results showed that compared with the control group, the mice in the irradiation group had a low discrimination ratio in the novel object recognition test (38.39 ± 3.69 vs. 28.82 ± 2.08, p<0.05), had higher number of IBA-1 positive cells (138.2 ± 3.7 vs. 159.6 ± 6.9, p<0.05), and remarkably enhanced expression levels of NLRP3, ASC, Caspase-1 protein (1.000 ± 0.066 vs. 1.341 ± 0.119, p<0.05; 1.000 ± 0.073 vs. 1.298 ± 0.083, p<0.05; 1.000 ± 0.039 vs. 1.603 ± 0.159, p<0.01), and NLRP3 and ASC mRNA in the prefrontal cortex (1.000 ± 0.046 vs. 1.372 ± 0.071, p<0.01; 1.000 ± 0.068 vs. 1.225 ± 0.069, p<0.05). Meanwhile, compared with the control group, the expression of inflammatory factors IL-1β and IL-18 was up-regulated in the irradiation group (1.000 ± 0.033 vs. 1.167 ± 0.059, p<0.05; 1.000 ± 0.196 vs. 1.614 ± 0.163, p<0.05). The results indicate that ionizing radiation may induce cognitive dysfunction by activating the NLRP3 inflammasome in the prefrontal cortex of mice.