孕期补充DHA对脂多糖所致宫内感染仔鼠脑组织TLR4表达的影响

摘要

目的 探讨宫内感染的孕鼠经二十二碳六烯酸(DHA)干预后,对围产期炎症暴露的仔鼠脑组织炎症状态的影响.方法 将孕鼠随机分为3组,①实验组(LPS+DHA组):孕期第1天开始给予DHA 130 mg/kg灌胃至分娩.于孕第17、18天连续2次腹腔注射LPS,剂量为350 μg/kg;②模型组(LPS组):无菌生理盐水灌胃,同期连续2次腹腔注射LPS,剂量同上;③对照组(NS组):无菌生理盐水灌胃,同期腹腔注射无菌生理盐水0.6 mL.取各组孕21天,生后第1、7、14天(G21,P1,P7,P14)的胎鼠及幼鼠脑组织,用苏木精-伊红染色法观察不同时间点脑组织的病理改变.Real time-PCR法检测脑组织Toll样受体4(TLR4)、IL-1β mRNA转录水平,Western blot 法检测脑组织TLR4、IL-1β蛋白表达水平.结果 模型组新生鼠平均出生体重较实验组及对照组减低(均P＜0.05).模型组脑组织苏木精-伊红染色见细胞水肿,组织疏松,细胞数减少.实验组脑细胞水肿较模型组减轻,细胞数减少不明显,而对照组脑组织炎性改变不明显.模型组及实验组IL-1β mRNA、IL-1β蛋白表达较对照组高(均P＜0.05),但实验组表达较模型组减低(均P＜0.05).模型组及实验组TLR4 mRNA、TLR4蛋白表达较对照组升高(均P＜0.05),实验组表达较模型组减少(均P＜0.05).结论 孕期LPS腹腔注射可引起孕鼠胎盘和胎儿的炎症反应,导致子代的脑损伤.孕期补充DHA能减少仔鼠脑内致炎细胞因子的表达,因此可能会降低宫内炎症暴露仔鼠脑损伤的发生率.%Objective To probe the effect of supplying DHA on the neonatal rat brain of intrauterine LPS exposure duration of pregnancy. Methods Pregnant SpragueDawley rats were divided into three groups: control group, model group( LPStreated) and experimental group( LPS+DHA-treated). LPS( 350 μg/kg body weight) was administered intraperitoneally to pregnant rats at 17th and 18th day of gestation,and the control group was treated with pyrogen free saline. Since the first day of gestation,DHA(130 mg/kg)was given to the pregnant rats of experimental group by intragastric administration every day,and the rest two groups were administrated pyrogen free water. Brain tissues were collected from the fetal rat at pregnant day 21 and neonatal rat at postnatal day 1(P1) ,P7 and P14. Real-time quantitative polymerase chain reaction( real-time PCR)analysis was used to detect the mRNA expression of TLR4 and IL-1β,and Western blotting was used to examine the TLR4 and IL-1β expression in brain tissues. Results The mean birth weight of the neonatal rats in the model group was significantly lighter than the control group and the experimental group(all P＜0. 05). Brain hematoxylin-eosin staining showed cellular edema,tissue raritas and cell population decreased in the model group. Brain cellular edema was relieved and cell population was not obviously decreased in the experimental group. Inflammatory response of the brain tissue in the control group was not obvious. The expression of IL-1β mRNA and IL-1β protein in the model group and experimental group was significantly increased as compared with that in the control group, but that in the experimental group was decreased as compared with the model group( all P＜0. 05). Compared to the control group,the expression of TLR4 mRNA and TLR4 protein in the model group and experimental group was significantly increased(all P＜0. 05) ,but that in the experimental group was decreased compared to the model group(all P ＜0. 05). Conclusion Intraperitoneal LPS(350 μg/kg)administration to pregnant rats induced an inflammatory response of placenta and fetus, finally resulting in brain injury. Maternal DHA treatment during pregnancy attenuates LPS-induced intrauterine and fetus brain inflammation by reducing the persistent expression of TLR4 and IL-1β in the neonatal rat brain,then promoting the inj ury recovery and the nervous system development.