Expression of nitric oxide synthase isoforms is reduced in late-gestation ovine fetal brainstem.
Expression of nitric oxide synthase isoforms is reduced in late-gestation ovine fetal brainstem.
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妊娠晚期绵羊胎儿脑干中一氧化氮合酶亚型的表达降低。
DOI：
10.1152/ajpregu.00722.2004
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Keller-Wood,Maureen
中科院分区：
文献类型：
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作者：
Wood,CharlesE;Chen,Gin-Fu;Keller-Wood,Maureen
胎儿压力感受性反射反应在妊娠晚期增强。压力感受性反射活动的一个重要调节因素是脑干核团中一氧化氮的产生，它整合了传入和传出反射活动。本研究旨在验证一氧化氮合酶(NOS)亚型在胎儿脑干中表达，以及这些酶中的一种或多种在妊娠晚期表达减少的假设。从已知胎龄的胎羊(80、100、120、130、145d及出生后1d和1wk)快速采集脑干组织。用实时荧光定量聚合酶链式反应方法检测绵羊一氧化氮合酶亚型的神经元(NNOS)、诱导型(INOS)和内皮型(ENOS)基因的表达。用蛋白质印迹方法在蛋白质水平上对这三种酶进行检测。在单独制备的组织学组织中，免疫染色的细胞模式在妊娠晚期胎羊的髓质中被鉴定出来。胎儿脑干中含有三种一氧化氮合酶亚型的mRNA和蛋白，其中以nNOS含量最高，其次是iNOS和eNOS。NNOS和iNOS的mRNA丰度在妊娠80d时最高，在较成熟的胎儿和出生后的动物中丰度显著下降。NNOS和eNOS蛋白丰度也随着发育年龄的增加而降低。NNOS和eNOS表达于神经元，iNOS表达于神经胶质细胞，eNOS表达于血管内皮细胞。我们的结论是，一氧化氮合酶的三种亚型都在胎儿脑干中结构性表达，并且随着妊娠的推进，这三种亚型的表达都会减少。我们推测，该脑区一氧化氮合酶表达减少在妊娠晚期胎儿压力感受器反射活动增加中起一定作用。
Fetal baroreflex responsiveness increases in late gestation. An important modulator of baroreflex activity is the generation of nitric oxide in the brainstem nuclei that integrate afferent and efferent reflex activity. The present study was designed to test the hypothesis that nitric oxide synthase (NOS) isoforms are expressed in the fetal brainstem and that the expression of one or more of these enzymes is reduced in late gestation. Brainstem tissue was rapidly collected from fetal sheep of known gestational ages (80, 100, 120, 130, 145 days gestation and 1 day and 1 wk postnatal). Neuronal (nNOS), inducible (iNOS), and endothelial (eNOS) mRNA was measured using real-time PCR methodology specific for ovine NOS isoforms. The three enzymes were measured at the protein level using Western blot methodology. In tissue prepared for histology separately, the cellular pattern of immunostaining was identified in medullae from late-gestation fetal sheep. Fetal brainstem contained mRNA and protein of all three NOS isoforms, with nNOS the most abundant, followed by iNOS and eNOS, respectively. nNOS and iNOS mRNA abundances were highest at 80 days' gestation, with statistically significant decreases in abundance in more mature fetuses and postnatal animals. nNOS and eNOS protein abundance also decreased as a function of developmental age. nNOS and eNOS were expressed in neurons, iNOS was expressed in glia, and eNOS was expressed in vascular endothelial cells. We conclude that all three isoforms of NOS are constitutively expressed within the fetal brainstem, and the expression of all three forms is reduced with advancing gestation. We speculate that the reduced expression of NOS in this brain region plays a role in the increased fetal baroreflex activity in late gestation.