Yu Lei, Vásquez-Vivar Jeannette, Jiang Rugang, Luo Kehuan, Derrick Matthew, Tan Sidhartha
Department of Pediatrics, NorthShore University HealthSystem, Evanston, IL 60201, USA.
Department of Biophysics and Free Radical Research Center & Redox Biology Program, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
Free Radic Biol Med. 2014 Feb;67:426-36. doi: 10.1016/j.freeradbiomed.2013.11.026. Epub 2013 Dec 4.
Tetrahydrobiopterin (BH4) is important for normal brain development as congenital BH4 deficiencies manifest movement disorders at various childhood ages. BH4 transitions from very low levels in fetal brains to higher "adult" levels postnatally, with the highest levels in the thalamus. Maternal supplementation with the BH4 precursor sepiapterin reduces postnatal motor deficits and perinatal deaths after 40-min fetal hypoxia-ischemia (HI) at 70% gestation, suggesting that brain BH4 is important in improving function after HI. We tested the hypothesis that the intrinsically low concentrations of BH4 made fetal neurons vulnerable to added insults. Brains were obtained from naïve fetal rabbits or after 40-min HI, at 70% (E22) and 92% gestation (E29). Neuronal cultures were prepared from basal ganglia, cortex, and thalamus, regions with different intrinsic levels of BH4. Cultures were grown with or without added BH4 for 48h. Cell survival and mitochondrial function were determined by flow cytometry. At E22, thalamic cells had the lowest survival rate in a BH4-free milieu, in both control and HI groups, whereas BH4 supplementation ex vivo increased neuronal survival only in HI cells. Neuronal survival was similar in all regions without BH4 at E29. BH4 supplementation increased cell survival and cells with intact mitochondrial membrane potential, from basal ganglia and cortex, but not thalamus. After E29 HI, however, the benefit of BH4 was limited to cortical neurons. We conclude that BH4 is important for fetal neuronal survival after HI especially in the premature thalamus. Supplementation of BH4 has a greater benefit at an earlier gestational age.
四氢生物蝶呤（BH4）对正常脑发育至关重要，因为先天性BH4缺乏会在儿童不同年龄段表现出运动障碍。BH4在胎儿脑中水平极低，出生后转变为较高的“成人”水平，丘脑水平最高。母体补充BH4前体蝶酰三嗪可减少妊娠70%时40分钟胎儿缺氧缺血（HI）后的出生后运动缺陷和围产期死亡，这表明脑BH4对改善HI后的功能很重要。我们测试了以下假设：BH4的内在低浓度使胎儿神经元易受额外损伤。在妊娠70%（E22）和92%（E29）时，从未经处理的胎儿兔或40分钟HI后的胎儿兔获取大脑。从基底神经节、皮质和丘脑制备神经元培养物，这些区域的BH4内在水平不同。培养物在添加或不添加BH4的情况下生长48小时。通过流式细胞术测定细胞存活率和线粒体功能。在E22时，在无BH4环境中，对照组和HI组的丘脑细胞存活率最低，而体外补充BH4仅增加HI细胞中的神经元存活率。在E29时，所有区域在无BH4时神经元存活率相似。补充BH4可增加基底神经节和皮质中具有完整线粒体膜电位的细胞存活率，但丘脑无此作用。然而，在E29 HI后，BH4的益处仅限于皮质神经元。我们得出结论，BH4对HI后胎儿神经元存活很重要，尤其是在早产的丘脑中。在更早的胎龄补充BH4有更大益处。
