宫内脂多糖暴露后新生大鼠脑髓鞘基质蛋白、胶质纤维酸性蛋白、白细胞介素-1β、肿瘤坏死因子-α的表达变化

Expression of myelin basic protein, glial fibrillary acidic protein, interleukin-1β and tumor necrosis factor-α in neonatal rats brain after intrauterine exposure on lipopolysaccharide

目的探讨宫内脂多糖（lipopolysaccharide，LPS）暴露后新生大鼠脑中炎症因子的表达与脑白质损伤的关系。方法向孕19dSD大鼠宫内注射LPS（0．4μg／孕囊间）构建宫内感染大鼠模型作为LPS组（n=14），对照组给予同体积的无菌生理盐水（n=10）。取1、3、7、11日龄新生大鼠脑标本（每组每时间点6只），通过免疫组织化学方法检测髓鞘基质蛋白与胶质纤维酸性蛋白在新生大鼠脑组织中的表达；采用逆转录-聚合酶链反应技术检测脑组织白细胞介素-1β、肿瘤坏死因子-α mRNA的水平。组间差异比较采用t检验。结果（1）LPS组孕鼠胎盘组织HE染色可见显著炎性细胞浸润、间质明显增生、毛细血管腔变窄。（2）LPS组11日龄新生大鼠小脑、间脑髓鞘基质蛋白表达分别为1．29±0．76和1．71±0．49，均较对照组（分别为2．43±0．79和2．50±0．76）明显减少（P均〈0．05）；而LPS组11日龄新生大鼠海马、胼胝体、间脑和小脑中胶质纤维酸性蛋白的表达分别为2．71±0．49、2．40±0．55、1．50±0．55和2．80±0．45，均较对照组（分别为1．75±0．50、1.50±0．58、1．00±0．00和1．60±0．55）增强（P均〈0．05）。（3）LPS组与对照组1、3、7、11日龄新生大鼠脑组织中白细胞介素-1β与肿瘤坏死因子-αmRNA的表达差异无统计学意义（P均〉0．05）。结论宫内LPS暴露导致宫内炎性改变、影响胎盘血供，并致新生大鼠低出生体重，可能引起新生大鼠出现以低髓鞘化及反应性星形胶质化为特征的脑白质损伤。

Objective To probe into the expression of inflammatory factrors and white matter damage after intrauterine lipopolysaccharide（LPS） exposure in neonatal rats brain. Methods LPS （0. 4 μg） was administrated into the intrauterine cavity between every two embryo sacs of SD rats at day 19 of gestation in LPS group（n= 14）, while pyrogen-free saline was administrated in control group （n= 10）. Neonatal brain tissues were collected at postnatal day 1, 3, 7 and 11. Reverse transcriptionpolymerase chain reaction analysis was used to examine mRNA expression of interleukin-1β and tumor necrosis factor-α, and immunohistochemistry was used to evaluate the expression of myelin basic protein and glial fibrillary acidic protein in neonatal brain tissues. Statistical analysis was performed using t test. Results Placental hematoxylin-eosin staining in the LPS group showed distinct inflammatory cell infiltration, prominent hyperplasia of interstitial tissue and narrowed capillary. Myelin basic protein in cerebellum and cerebrum of neonatal rats at postnatal 11 days in LPS group was much weaker than in control group （cerebellum： 1.29 ± 0.76 vs 2.43 ±0.79, t= 2.038,P= 0. 045; cerebrum： 1.71± 0.49 vs 2.50 ± 0. 76, t = 2. 420, P= 0. 032）. Glial fibrillary acidic protein of neonatal rats brain at postnatal 11 days in LPS group was much stronger than in control group （hippocampus： 2.71±0.49 vs 1.75±0.50, t=-3.029, P=0.026. corpus callus： 2.40± 0.55 vs 1.50±0.58, t=-2.646,P=0.019, cerebrum： 1.50±0.55 vs 1.00±0.00, t=-2.236, P=0.049. cerebellum： 2.80±0.45 vs 1.60±0.55, t = - 3. 08 , P = 0. 009 ）. But there was no statistical difference between LPS group and control group in the expressions of IL-1β and TNF-α mRNA in neonatal rats brain at each time point. Conclusions Intrauterine LPS exposure may decrease the placental blood flow resulting in neonatal low birth weight and white matter damage, which characterized by astrogliosis and hypomyelination.