孕鼠腹腔注射脂多糖致新生鼠肺损伤模型的构建

Establishment of an optimal animal model of lung injury in neonate rat after maternal intrauterine infection induced by intraperitoneal injection of lipopolysaccharides

目的：探讨孕鼠腹腔注射脂多糖（lipopolysaccharide,LPS）致新生鼠肺损伤模型的构建方法。方法：孕18 d SD大鼠随机分为生理盐水对照组（control组）和LPS组,观察腹腔注射不同剂量LPS（2.5、2.0、1.5、1.0、0.5 mg/kg）与等量灭菌生理盐水后的孕鼠反应并统计孕鼠死亡率及流产率,依上述实验结果选定较低死亡率的LPS剂量。分别予孕鼠腹腔注射LPS（0.9、0.8、0.7、0.6、0.5 mg/kg）及等量灭菌生理盐水后记录各组新生鼠肺的病理评分、湿/干重比值（W/D）及肺组织中肿瘤坏死因子（tumor necrosis factor,TNF）-αmRNA、白细胞介素（interleukin,IL）-1βmRNA和TNF-α蛋白的表达量。进一步研究LPS 0.7 mg/kg组中孕19 d胎盘、胎肺及新生鼠生后第1、4、7 d肺组织中炎症因子（TNF-α、IL-1β）mRNA表达量变化与组织病理改变。结果：①LPS组中随着药物剂量递减,孕鼠死亡率及流产率逐渐降低,当LPS剂量小于1.0 mg/kg时孕鼠死亡率及流产率降低至25%以下;②LPS 0.5-1.0 mg/kg时,与对照组比较,LPS〈0.7 mg/kg时新生鼠肺病理评分、W/D、组织TNF-α及IL-1βmRNA表达差异无统计学意义（P均〉0.05）,LPS≥0.7 mg/kg时上述指标均显著升高,且差异有统计学意义（P均〈0.05）;③孕鼠腹腔注射LPS 0.7 mg/kg时,胎盘、胎肺炎症因子较对照组显著升高,且LPS组新生鼠生后第1、4、7天肺组织中TNF-α、IL-1βmRNA表达水平均显著高于对照组（P均〈0.05）。结论：SD大鼠孕18 d腹腔注射0.7 mg/kg LPS可导致新生鼠肺病理损害、肺水肿,炎症因子TNF-α、IL-1β增高,并延续到生后7 d,是制备宫内感染新生鼠肺损伤模型稳定、可靠的方法。

Objective：To establish an reliable and stable method of establishing an optimal animal model of lung injury in neonate rat intraperitoneal injection of lipopolysaccharides（LPS）.Methods：Pregnant Sprague-Dawley rats on gestation day 18 were randomly divided into the control group and the LPS experimental group.Rats were injected intraperitoneally with 0.5,1.0,1.5,2.0 and 2.5 mg/kg LPS,respectively,in the LPS groups and with equal amount of saline in the control group,and then the mortality and abortion ratio of pregnant rats rate were measured.According to the statistical results,we next selected low mortality doses of LPS（0.9,0.8,0.7,0.6,and 0.5 mg/kg） and intraperitoneally injected to pregnant rats.Lung tissues were collected from neonatal rat at postnatal day 1.The indexes of pathological score and wet/dry weight ratio（W/D） of lung lobes were observed.The mRNA expression of TNF-α and IL-1β,and the TNF-α protein expression in lung tissues were examined.Furthermore,to study the LPS of0.7 mg/kg dose,the mRNA expression of TNF-α,IL-1β in placental and fetal lung tissues were measured on day 19.The same indexes of neonatal rats lung were also examined on day 1,4 and 7 after natural birth,respectively.Results：①The mortality and abortion ratios of pregnant rats were decreased gradually with the decreasing LPS doses.When the dosage of LPS was less than 1.0 mg/kg,these two indexes were reduced to below 25%.②When the dosage of LPS ranged from 0.5 to 1.0 mg/kg,pathological score,W/D score and the mRNA levels of TNF-α,IL-1β were significantly higher than those in the control group under the condition of LPS≥0.7mg/kg（P〈 0.05）.When the dosage of LPS 0.7 mg/kg,the above indexes showed no statistical significance（P〈 0.05）.③When the dosage of LPS = 0.7 mg/kg,the expressions of TNF-α,IL-1β mRNA in placenta and fetal issues increased more obviously（P〈 0.05） than that in the control group.Compared to the control group,the mRNA expression of TNF-α and IL-1β in lung tissues of neonatal rats on day 1,4,and 7 was significantly increased（all P〈 0.05）.Conclusion：Intraperitoneal LPS（0.7 mg/kg） given to pregnant SD rats on 18 th day of gestation led to lung injury,and pulmonary edema and increase TNF-α and IL-1β in newborn rats,which continued into the 7th day after birth.This is a stable and reliable method to construct the model of lung injury in neonate rat with intrauterine infection.