脑源性神经营养因子在宫内缺氧环境中对胎盘及血脑屏障通透性的实验研究

目的 探讨外源性脑源性神经营养因子(brain—derived neurotrophic factor，BDNF)在官内缺氧环境下能否通过胎盘屏障进入胎鼠体内，再通过胎鼠血脑屏障进入胎脑而发挥其生物功能。方法 钳夹孕17d(孕中期)鼠子官动脉30min后，经孕鼠尾静脉注射不同剂量的^125I标记的BDNF(^125I-BDNF)。24、48及72h后取孕鼠胎盘、羊水及胎鼠脑、心、肺、肝、肾，检测和比较各组织中BDNF的放射活性。结果 (1)BDNF能够部分通过胎盘屏障，胎鼠体内检测到^125I-BDNF的分布。(2)^125I-BDNF在胎盘屏障通透性及在各组织中分布的量随外源性^125I—BDNF注射剂量增加而升高。(3)BDNF在胚胎缺血缺氧时，能通过血脑屏障到达胚鼠大脑。(4)缺氧缺血时BDNF对胎盘屏障和血脑屏障的通透性增加。结论外源性BDNF在官内缺血缺氧时能够部分通过胎盘屏障和血脑屏障。

Study on permeability of brain-derived neurotrophic factor through placental barrier and fetal blood-brain barrier after transient uteroplacental ischemia

Objective To investigate whether exogenic brain derived neurotrophic factor (BDNF) can permeate placental barrier into fetus and further through fetal blood brain barrier(BBB) after transient ischemia. Methods Seventeen day pregnant rats were selected. The uterine arteries of the rats were clamped for 30 minutes in experimental group. BDNF labeled with 125 I was injected into the rats through caudal veins. The radioactivity of BDNF in different fetal organs was measured at 24 h, 48 h and 72 h. Results 125 I BDNF was detected in amniotic fluid, placenta and fetal organs including brain, heart, lung, liver and kidney. This indicated that BDNF partly permeated placental barrier. The permeability of BDNF through placenta barrier and fetal BBB increased with the increased dose injected. BDNF reached the fetal brain through BBB under hypoxia eschemia condition. The rates of penetration of BDNF through placental barrier and BBB increased under the condition of fetal ischemia and hypoxia. Conclusions Exogenic BDNF may partly go through placental barrier and BBB into fetal brain, which makes it possible for BDNF to be a treatment for fetus suffered from ischemia and hypoxia.