新生期氢氧化铝暴露致小鼠成年后社交和认知功能障碍的实验研究

Neonatal aluminum hydroxide exposure induces social and cognitive dysfunction in adulthood mice

目的探究小鼠新生期氢氧化铝[Al(OH)_(3)]暴露对小鼠成年后社交行为和认知功能的影响。方法将16只SPF级、体质量为2~3 g的新生C57BL/6雄性小鼠分成2组(n=8):正常对照组(C57+Sal)和新生期Al(OH)_(3)处理组[C57+Al(OH)_(3)]。以肌肉注射方式在小鼠出生后第3、5、7、10、12天分别以290、75、100、110、50μg/kg体质量的剂量进行Al(OH)_(3)处理,对照组小鼠肌肉注射等体积的生理盐水。用旷场实验、明暗箱实验、高架十字迷宫实验评价小鼠的运动功能和焦虑样行为;用理毛实验和埋珠实验评估小鼠的重复刻板样行为;用三箱社交实验评估小鼠的社交能力;用新物体识别、Y迷宫、筑巢实验评价小鼠的短期记忆功能和认知功能;用水迷宫实验评价小鼠的空间记忆能力和学习能力。采用Sox2、GFAP、PCNA免疫荧光检测小鼠海马内神经干细胞和增殖细胞数量;NeuN、S100β、Iba1免疫荧光检测海马内神经元、星形胶质细胞、小胶质细胞的分化。结果与C57+Sal组比较,C57+Al(OH)_(3)组小鼠在旷场实验中总运动距离、总中心时间、分段运动距离无显著变化,在高架十字迷宫实验中,开臂时间占比上无显著变化,在明暗箱实验中,暗箱时间占比上无显著变化;在三箱社交实验中,C57+Al(OH)_(3)组小鼠在箱体时间上无差异,在箱体偏好系数和嗅探偏好系数上均表现出对陌生物体的偏好(P<0.05),在理毛实验中,理毛时间显著高于对照组(P<0.05);在新物体识别实验中,C57+Al(OH)_(3)组新物体识别系数显著低于对照组(P<0.05),Y迷宫实验中自发交替探索行为比显著低于对照组(P<0.05);在Morris水迷宫实验中,C57+Al(OH)_(3)组在目标象限时间显著低于对照组(P<0.05)。与C57+Sal组比较,C57+Al(OH)_(3)组海马齿回内神经干细胞的数量显著减少(P<0.05),颗粒层厚度变薄(P<0.01),成熟星形胶质细胞分化增加(P<0.05)。结论新生期Al(OH)_(3)暴露可导致小鼠成年后出现社交和认知功能异常,其机制可能与海马发育缺陷有关。

Objective To investigate the effects of neonatal aluminum hydroxide[Al(OH)_(3)]exposure in mice on social behavior and cognitive function in their adulthood.Methods Sixteen newborn C57BL/6 male mice of SPF class with body mass of 2~3 g were divided into 2 groups(n=8):the normal control group(C57+Sal)and the neonatal Al(OH)_(3)treated group[C57+Al(OH)_(3)].Al(OH)_(3)was administered by intramuscular injection at doses of 290,75,100,110 and 50μg/kg on postnatal days of 3,5,7,10 and 12,respectively.The control group received intramuscular injections of equal volumes of saline.The open field test,light-dark box test,elevated plus maze test were used to evaluate the motor function and anxiety-like behavior of mice;The grooming test and marble burying test were used to assess the repetitive stereotypic behavior of mice;The three-chamber social test was used to evaluate the social ability of mice;The novel object recognition,Y-maze and nest building test were used to evaluate the short-term memory function and cognitive function of mice;The Morris water maze test was used to evaluate the spatial memory ability and learning ability of mice.Sox2,GFAP,PCNA immunofluorescence assay was used to detect the number of neural stem cells and proliferating cells in the hippocampus;NeuN,S100β,Iba1 immunofluorescence assay was used to detect the differentiation of neurons,astrocytes and microglia in the hippocampus.Results Compared with the C57+Sal group,the C57+Al(OH)_(3)group showed no significant changes in total distance,total center time and segmental distance in the open field test,as well as no significant changes in open arm time percentage in the elevated plus maze test and the percentage of dark box time in the light-dark box test.In the three-box socialization test,the C57+Al(OH)_(3)group showed no difference in chamber time,a preference for unfamiliar objects in both chamber preference index and sniffing preference index(P<0.05),and significantly higher grooming time than the control group(P<0.05);The results of novel object recognition test and Y-maze test showed the C57+Al(OH)_(3)group had a significantly lower novel object recognition index and spontaneous alternation exploration behavior ratio than those in the control group(P<0.05);In the morris water maze test,the C57+Al(OH)_(3)group had a significantly lower target quadrant time than those in the control group(P<0.05).Compared with the C57+Sal group,the C57+Al(OH)_(3)group had a significantly reduced number of neural stem cells in the hippocampal dentate gyrus(P<0.05),thinner granule layer thickness(P<0.01)and increased differentiation of mature astrocytes(P<0.05).Conclusion Neonatal Al(OH)_(3)exposure can lead to social and cognitive dysfunction in adult mice,which may be related to hippocampal developmental defects.