孕鼠DHA干预对宫内感染仔鼠脑组织炎症状态的影响

Effect of DHA intervention of pregnant rats with intrauterine infection on inflammation state of cerebral tissues of neonatal rats

目的:探讨宫内感染的孕鼠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:本实验将孕鼠随机分为3组,①对照组:孕期第1天开始无菌生理盐水灌胃至分娩,于孕第17、18天腹腔注射无菌生理盐水0.6 ml。②LPS组(模型组):无菌生理盐水灌胃,孕第17、18天连续两次腹腔注射LPS,计量为350μg/kg。③LPS+DHA组(干预组):孕期第1天开始给予DHA130 mg/kg灌胃至分娩,于孕第17、18天连续两次腹腔注射LPS,计量同②。取各组孕21天(G21),生后P1、P7、P14脑组织,用HE染色法观察不同时间点脑组织的病理改变,用免疫组化方法检测脑组织中OX42阳性小胶质细胞的表达情况。用Q-RT-PCR检测脑组织中细胞因子TNF-α的mRNA转录水平。结果:模型组脑白质早期可见水肿和形态较幼稚的细胞,甚至伴有局灶性出血,后期脑白质内神经纤维走向紊乱,组织疏松,细胞数减少。干预组早期脑白质可见较多水肿细胞,无明显出血灶和软化灶,P14时与对照组形态接近。与对照组相比:①模型组小胶质细胞OX42阳性表达在P14时仍较高(P<0.05);干预组至P7时亦较高(P<0.05),P14时无明显差异(P>0.05);干预组在各时间点与模型组比较均较低(P<0.05)。②模型组TNF-αmRNA的表达在P7时仍较高(P<0.05),而在P14无显著差异(P>0.05);干预组TNF-αmR-NA的表达较模型组低直至P7(P<0.05),而在P14无显著差异(P>0.05)。结论:宫内LPS感染可导致胎儿脑组织炎性反应,孕期补充DHA能通过减少小胶质细胞的持续活化和炎症细胞因子的表达而抑制胎儿脑组织的炎症反应,促进脑损伤的恢复。

Objective：To explore the effect of DHA intervention of pregnant rats with intrauterine infection on inflammation state of cerebral tissues of neonatal rats exposure to perinatal inflammation. Methods：All the neonatal rates were divided into three groups randomly.The neonatal rats in control group were treated with pouring physiological saline solution into stomach until delivery from the first day of pregnancy,then on the 17th day and 18th day during pregnancy,the rats were treated with intraperitoneal injection of physiological saline solution（0.6 ml）.The rats in LPS group（model group） were treated with pouring physiological saline solution into stomach,then on the 17th day and 18th day during pregnancy,the rats were treated with intraperitoneal injection of LPS,the amount was 350μg/kg.The rats in LPS＋DHA group（intervention group） were treated with pouring DHA（130 mg/kg） into stomach until delivery from the first day of pregnancy,then on the 17th day and 18th day during pregnancy,the rats were treated with intraperitoneal injection of LPS,the amount was 350μg/kg.The brain tissue specimens of rats on the 21nd day of pregnancy,the first day,seventh day and fourteenth day after birth were obtained in the three groups,HE staining method was used to observe the pathological changes of brain tissues at different time points,immunohistochemical method was used to detect the expression level of microglial cells with positive OX42 in brain tissues.The transcriptional level of TNF-α mRNA in brain tissues was detected by Q-RT-PCR. Results：In model group,edema and cells with immature morphology were found at early period in white matter,even combined with focal hemorrhage,at late period,the trend of nerval fiber in white matter was in disorder,the tissues were loose,the number of cells decreased.In intervention group,many oedematous cells were found at early period in white matter,no apparent hemorrhagic focus and reticular softening lesion were found,on the fourteenth day of pregnancy,the morphology was similar to that in control group.Compared with control group,the positive expression rate of OX42 in microglial cells on the fourteenth day of pregnancy in model group was higher（P0.05）;in intervention group,the positive expression rate of OX42 on the seventh day of pregnancy was higher（P0.05）,but there was no significant difference on the fourteenth day of pregnancy（P0.05）.The positive expression rates of OX42 at different time points in intervention group were significantly lower than those in model group（P0.05）.In model group,the expression level of TNF-α mRNA on the seventh day of pregnancy was higher（P0.05）,but there was no significant difference on the fourteenth day of pregnancy（P0.05）;the expression level of TNF-α mRNA in intervention group was significantly lower than that in model group until the seventh day of pregnancy（P0.05）,but there was no significant difference on the fourteenth day of pregnancy（P0.05）. Conclusion：Intrauterine LPS infection can induce inflammation reaction of fetal brain tissues,supplementation of DHA during pregnancy can promote the recovery of brain injury by reducing the continuous activation of microglial cells and the expression of inflammatory cytokines and then inhibit inflammatory reaction of fetal brain tissues.