目的 通过建立微塑料暴露小鼠模型探讨微塑料暴露致皮质铁死亡的影响,以期为微塑料暴露致神经损伤的防治提供新的线索.方法 SPF级雄性C57小鼠40只按体重随机分为对照组、低微塑料组、中微塑料组、高微塑料组,每组10只.微塑料暴露组小鼠分别以25、50和100mg/kg纳米聚苯乙烯灌胃,连续染毒8周,对照组每天灌胃相同剂量纯水.染毒结束后,以新物体识别实验检验小鼠的神经行为变化;以HE染色观察小鼠皮质病理变化;以试剂盒检测小鼠皮质组织中二价铁(Fe2+)、丙二醛(MDA)和谷胱甘肽(glutathione,GSH)的含量;以Western blot法检测小鼠皮质组织中二价金属铁离子转运体1(DMT1)、铁转运蛋白(ferroportin,FPN1)、转铁蛋白受体1(transferrin receptor 1,TFR1)、谷胱甘肽过氧化物酶4(glutathione peroxidase 4,GPX4)和溶质载体家族 7 成员 11(solute carrier family 7 member 11,SLC7A11)蛋白的表达情况.结果 染毒期间,低微塑料、中微塑料与高微塑料组小鼠体重与对照组相比无显著差异.新物体识别实验结果显示,与对照组相比,中微塑料组和高微塑料组新物体识别指数显著下降(P＜0.05).HE染色结果显示,与对照组相比,低微塑料组小鼠皮质中出现神经细胞深染,结构模糊,核固缩现象;中微塑料组及高微塑料组小鼠皮质及海马中神经细胞深染,结构模糊,核固缩现象进一步加剧.与对照组相比,各微塑料组小鼠脑皮质中铁含量和MDA含量显著升高(P＜0.05),GSH含量在中微塑料组和高微塑料组中显著下降(P＜0.05);同时,TFR1表达水平在各微塑料组小鼠脑皮质中均较对照组显著升高(P＜0.05),中微塑料和高微塑料组小鼠脑皮质中FPN1表达水平显著降低(P＜0.05),DMT1表达水平显著升高(P＜0.05);此外,与对照组相比,GPX4与SLC7A11在中微塑料组与高微塑料组小鼠皮质中的表达水平显著降低(P＜0.05).结论 微塑料暴露可引起小鼠新物体识别能力下降,其中微塑料引起皮质神经细胞铁稳态失调导致铁死亡是诱导神经损伤的机制之一.
Role of ferroptosis in cortical damage induced by microplastic exposure in mice
Objective To understand the role of ferroptosis in cortical damage induced by microplastic exposure in mice,and to provide new clues for the prevention and treatment of nerve injury caused by microplastic exposure.Methods Forty SPF male C57 mice were randomly divided into control group,low,moderate and high exposure exposure groups according to their weight,with 10 mice in each group.The mice in the microplastics exposure groups were given 25 mg/kg,50 mg/kg and 100 mg/kg nano polystyrene respectively through gavage for 8 consecutive weeks,and the control group was given the same dose of pure water every day.After the end of exposure,the new object detection experiment was used to examine the changes in the neural behavior of mice.HE staining was used to observe the pathological changes in the mouse cortex.The contents of iron,malondialdehyde(MDA)and glutathione(GSH)in the cortex of mice were detected with the kit.Western blotting was used to detect the protein expression of divalent metal ion transporter 1(DMT1),ferroportin(FPN1),transferrin receptor 1(TFR1),glutathione peroxidase 4(GPX4)and solute carrier family 7 member 11(SLC7A11)in mouse cortex.Results During the exposure period,there was no significant difference in the weight of mice in low,moderate and high dose groups compared with the control group.The new object detection index in moderate and high exposure groups decreased significantly compared with the control group(P＜0.05).Compared with the control group,deep staining,fuzzy structure and pyknosis of nerve cells appeared in the cortex of mice in low exposure group.The neurons in the cortex and hippocampus in moderate and high dose groups were deeply stained,the structure was blurred,and the pyknosis phenomenon was further aggravated.Compared with the control group,the iron content and MDA content in the brain cortex of mice in each exposure group increased significantly,and the GSH content in the moderate and high exposure groups decreased significantly(P＜0.05).At the same time,the expression level of TFR1 in the brain cortex of mice in each exposure group was higher than that in the control group(P＜0.05).The expression level of FPN1 in the cortex in moderate and high exposure groups was lower,and the expression level of DMT1 was higher(P＜0.05).In addition,compared with the control group,the expression level of GPX4 and SLC7A11in the cortex in moderate and the high exposure groups significantly decreased(P＜0.05).Conclusion Microplastics exposure may cause new object recognition capability decrease in mice,and it may be involved in which that microplastics cause iron homeostasis disorder in cortical neurons and lead to ferroptosis.
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