摘要
目的 探讨噪声接触导致大鼠认知功能障碍中黑色素瘤缺乏因子2(AIM2)的作用.方法 于2023年4月,将16只雄性Wistar大鼠随机分为对照组和噪声组,每组8只.噪声组大鼠置于50 cm× 50cm×40cm的透明箱子中,每天施加声压级100dB(A)的白噪声4h,连续30d.对照组大鼠置于相同的箱子中,环境噪声＜60dB(A).30 d噪声接触完成后,用Morris水迷宫实验测试大鼠的学习和记忆功能;苏木精-伊红(HE)染色观察海马组织的病理形态变化;Western blot检测AIM2、胱天蛋白酶-1(Caspase-1)、凋亡相关斑点样蛋白(ASC)、白细胞介素(IL)-1 β、IL-18、离子钙结合衔接分子-1(Iba-1)和胶质纤维酸性蛋白(GFAP)的蛋白表达水平;免疫组化染色观察海马组织中Iba-1和GFAP的表达情况;免疫荧光双染测定AIM2与Iba-1或GFAP的共定位情况.结果 与对照组比较,噪声组大鼠在第3、4、5天的逃避潜伏期分别增加了 16.29、17.71、20.26s.第6天噪声组大鼠停留在目标象限的时间[(7.25±2.27)s]和穿越平台的次数[(1.13±0.64)次]明显低于对照组[(15.64±3.99)s 和(4.25±2.12)次](P＜0.05).噪声组大鼠海马齿状回(DG)区小胶质细胞和星形胶质细胞数量(27.00±2.65和43.33±5.51)明显高于对照组(14.67±3.06和20.00±4.58)(P＜0.05),且细胞胞体变大、分支数量增加且变粗.噪声组大鼠海马的炎症因子裂解(Cleaved)-IL-1β和Cleaved-IL-18的蛋白表达水平(1.55±0.19和1.74±0.12)明显高于对照组(1.00±0.11 和 1.00±0.13)(P＜0.05).噪声组大鼠海马的 AIM2、Cleaved-Caspase-1 和 ASC 蛋白表达水平(1.19±0.09、1.34±0.07 和 1.14±0.01)高于对照组(1.00±0.07、1.00±0.14 和 1.00±0.06)(P＜0.05).噪声组大鼠海马中AIM2与Iba-1或GFAP共定位细胞数量(28.67±4.04和40.67±5.13)明显高于对照组(15.67±4.04和17.67±3.79)(P＜0.05).结论 噪声接触可能会激活大鼠海马神经胶质细胞中的AIM2炎症小体,释放大量的炎症因子,引起神经炎症损伤神经元.
Abstract
Objective To explore the effect of the absent in melanoma 2(AIM2)-mediated neuroinflammation in noise-induced cognitive dysfunction in rats.Methods In April 2023,sixteen male Wistar rats were randomly divided into control group and noise group,with 8 rats in each group.The rats in the noise group were placed in 50 cmx50 cmx40 cm transparent boxes and exposed to 100 dB(A)white noise with a sound pressure level of 100 dB(A)(4 h/d for 30 d).At the same time,rats in the control group were kept in similar boxes with environmental noise less than 60 dB(A).After 30 days of noise exposure,the Morris water maze experiment was applied to test the learning and memory abilities of the rats;the pathological morphology of hippocampal tissues was observed by Hematoxylin-Eosin(HE)staining.Western blot was used to detect the protein expression levels of AIM2,cysteinyl aspartate specific proteinase-1(caspase-1),apoptosis-associated speck-like protein(ASC),interleukin-1β(IL-1β),IL-18,ionic calcium-binding articulation molecule-1(Iba-1),and glial fibrillary acidic protein(GFAP).The expression of both Iba-1 and GFAP in hippocampal tissue was assessed by immunohistochemical staining.The co-localization of AIM2 with Iba-1 or GFAP was determined by immunofluorescence double staining.Results Compared with the control group,the escape latency of rats in the noise group was increased by 16.29 s,17.71 s,and 20.26 s on days 3,4,and 5,respectively.On day 6,the noise-exposed rats spent shorter time in the target quadrant and had fewer times in crossing the platform[(7.25±2.27)sand(1.13±0.64)times]than the control group[(15.64±3.99)sand(4.25±2.12)times](P＜0.05).After noise exposure,hippocampal neurons of rats displayed marked nuclear hyperchromatic and pyknosis phenomenon.The noise-exposed rats had higher numbers of both microglia and astrocytes(27.00±2.65 and 43.33±5.51)in the DG area of the hippocampus relative to the control group(14.67±3.06 and 20.00±4.58)(P＜0.05).Moreover,the glial cells in the noise group had larger cell cytosol with more and thicker branches.The protein expression levels of inflammatory cytokines Cleaved-IL-1β and Cleaved-IL-18 in the hippocampus of rats in the noise group(1.55±0.19 and 1.74±0.12)were significantly higher than the control group(1.00±0.11 and 1.00±0.13)(P＜0.05).After noise exposure,the protein expression levels of AIM2,Cleaved-Caspase-1 and ASC(1.19±0.09,1.34±0.07 and 1.14±0.01)were higher than the control group(1.00±0.07,1.00±0.14 and 1.00±0.06)and differences between the two groups were statistically significant(P＜0.05).A significant increase in the number of cells co-localizing AIM2 with Iba-1 or GFAP in the noise group(28.67±4.04 and 40.67±5.13)compared with the control group(15.67±4.04 and 17.67±3.79),and statistically significant differences were observed between the two groups(P＜0.05).Conclusion Noise exposure may activate the AIM2 inflammasome in hippocampal glial cells of rats,releasing excessive inflammatory cytokines and causing neuroinflammation that damages neurons.
基金项目
广州市科技局重点研发计划(202206010061)
广州市医学重点学科建设项目(2021-2023)()
广州市市校(院)企联合专项(2023A03J0502)
广州市卫生健康科技项目(20221A011060)
广东省医学科学技术研究项目(B2023347)
NETL
NSTL
万方数据