近足月胎兔持续宫内缺氧缺血性脑损伤模型的建立

Establishment of intrauterine hypoxic-ischemic brain damage model in near term fetal rabbits

目的:建立近足月(29 d胎龄)胎兔持续宫内缺氧缺血性脑损伤模型,为深入研究新生儿缺氧缺血性脑损伤发病机制和治疗提供合适模型。方法:选择孕29 d健康新西兰白兔24只,联合全身麻醉和腰麻对孕兔进行麻醉,从左侧股动脉插入4F Fogarty动脉取栓导管,实验组向导管球囊内注入生理盐水0.3 mL阻断孕兔子宫血供,阻断时间分别为20 min、25 min、28 min、30 min和40 min,每组4只;对照组插管后不注入生理盐水,共4只。24 h后行剖宫产,记录新生兔一般情况,评估新生兔神经行为学和脑组织病理学改变。结果:麻醉过程中孕兔生命体征稳定,未发生低氧血症,对麻醉耐受性良好。实验组向导管球囊内注入生理盐水0.3 mL后孕兔右侧股动脉搏动消失,血压测不出;而对照组血压无明显波动(P>0.05)。持续阻断子宫血供导致胎兔和新生兔死亡,存活新生兔神经行为学异常,脑细胞发生凋亡。阻断子宫血供20 min时,未发现死胎,新生兔行为学和脑组织病理学改变不明显;阻断子宫血供25 min和28 min时,死胎率分别为12.9%和40.6%,存活新生兔出现不同程度的神经行为异常,脑组织切片发现神经元细胞肿胀,小胶质细胞活化,脑细胞凋亡;而阻断子宫血供超过30 min时,死胎率高达80.0%。结论:持续阻断孕兔子宫血供导致胎兔死亡、新生兔神经行为学异常及脑组织病理学改变,且不同阻断时间引起不同程度的脑损伤;持续阻断子宫血供25～28 min,可为缺氧缺血性脑损伤的相关研究提供合适的胎儿期全身性缺氧缺血性脑损伤胎兔模型。

AIM： To establish intrauterine hypoxic-ischemic brain damage（HIBD） model in near term fetal rabbits at 29 d gestation age for the investigation of the pathogenesis and treatment of newborn HIBD.METHODS： Twenty-four pregnant New Zealand white rabbits at 29th gestational day were chosen for this project.Under combined general anesthesia and spinal anesthesia,a 4F Fogarty arterial embolectomy catheter was introduced into the left femoral artery.The blood supply of uterus in experiment group was blocked by inflating the catheter balloon with 0.3 mL saline for 20 min,25 min,28 min,30 min and 40 min（n=4 for each experimental time group）.The catheter balloon was not inflated in control group（n=4）.All pregnant rabbits were subject to cesarean section 24 h after the experimental procedure to induce hypoxia-ischemia to the fetus.The general conditions of the newborn rabbits were recorded,and the neurobehavioral damage and histology of the brain tissue were assessed.RESULTS： During the entire procedure,the pregnant rabbits had stable vital signs,no hypoxia happened,and had a good tolerance to the anesthesia program.When the balloon was inflated,the pulses of right femoral artery disappeared and the right leg blood pressure became non-detectable in experimental groups.In contrast,no fluctuation of the right leg blood pressure in control group（P0.05） was observed.Intrauterine hypoxia-ischemia caused neonatal and fetal rabbit death,neurobehavioral damage and brain cell death.When the balloon was inflated for 20 min,all fetal rabbits were alive and had no obvious neurologic damage.For 25～28 min,the stillbirth rates were 12.9% and 40.6%,respectively,while the live neonatal rabbits manifested neurobehavioral damage,edema neural cells,activated microglia cells and apoptotic brain cells.When blocking time beyond 30 min,above 80% fetal rabbits died.CONCLUSION： Continuous blockage of uterine blood supply in pregnant rabbits causes neonatal rabbit death,neurobehavioral damage and brain cell death.Different blocking time arouses different levels of brain damage.Continuous blockage of uterine blood supply for 25-28 min can establish fetal generalize hypoxic-ischemic brain damage rabbit model,which is a good animal model for the investigation of newborn HIBD.