Gamma-Aminobutyric Acid is Synthesized by Endothelial Cells: Implications in Preeclampsia

摘要 先兆子痫影响3%到6%的孕妇，对母亲和婴儿造成毁灭性的影响。 然而，没有分子靶点可以推动药物发现走向成功或早期的治疗。 可以在症状发展之前预测这种综合征发病的诊断标记物。我们有 首次观察到中枢抑制性神经递质γ-氨基丁酸(GABA) 血管内皮细胞合成并释放到体循环中，因此我们的发现 解释体循环中GABA的一个重要来源。此外，脑组织中的GABA水平 先兆子痫患者与非妊娠妇女相比循环减少，但其机制(S)是 不知道。GABA在内皮细胞中的作用，以及如何减少合成和释放 GABA存在于子痫前期，其在子痫前期病因学中的意义尚不清楚。在预赛中 实验中，我们观察到从体外培养的人脐静脉内皮细胞(HUVEC) 与正常HUVEC相比，子痫前期孕妇合成和释放的GABA较少 怀孕的女人。我们还在子痫前期人脐静脉内皮细胞中发现了L-甲硫基谷氨酸(LMG)，它抑制了 内皮细胞合成GABA。 基于我们新的观察结果，我们假设：“内皮细胞合成减少和 GABA的释放与内皮功能障碍有关，并参与了Pre-Pre的发病机制。 子痫“，我们的假设将通过以下三个具体目标进行检验。 具体目标1：我们将评估HUVEC是否来自患有子痫前期的母亲(PE-HUVEC) 与正常怀孕的母亲相比，合成和释放的GABA更少。 具体目标2：我们将比较GABA在维持HUVEC正常功能中的作用 与游离脂肪酸(FFA)氧化、丙酮酸氧化、ATP合成、 黏附分子表达和活性氧(ROS)产生的调控及其机制 PE-HUVEC中GABA合成减少会影响这些过程，从而导致内皮细胞功能障碍。 具体目标3：(A)我们将评估内源性GABA合成抑制剂LMG的效果 在PE-HUVEC中，对NP-HUVEC和HAEC的一些GABA介导的功能进行了特定的评估 目的2和(B)我们将定量测定正常人脐血和母血中的GABA和LMG水平 并将其与子痫前期妊娠的脐带和母体水平相关联。

Abstract Preeclampsia affects 3 to 6 % of pregnant women with devastating effects on the mother and the baby. However, there are no molecular targets that could drive drug discovery towards therapeutic success or early diagnostic markers that could predict the onset of this syndrome prior to development of symptoms. We have for the first time observed that gamma Aminobutyric acid (GABA) a central inhibitory neurotransmitter is synthesized and released by vascular endothelial cells into the systemic circulation and our findings therefore explain one important source of GABA in the systemic circulation. Furthermore, the level of GABA in the circulation is decreased in preeclampsia compared to non-pregnant women but the mechanism(s) involved is not known. The actions of GABA in the endothelial cells, and how a decrease in synthesis and release of GABA occurs in preeclampsia and its significance in the etiology of preeclampsia is not known. In preliminary experiments, we observed that human umbilical venous endothelial cells (HUVEC) obtained from pre- eclamptic pregnancies synthesize and release less GABA when compared with HUVEC obtained from normal pregnant women. We have also identified L-methionyl glutamate (LMG) in preeclamptic HUVEC which inhibits GABA synthesis by endothelial cells. Based on our novel observations, we HYPOTHESIZE that: “a decrease in endothelial synthesis and release of GABA is responsible for endothelial dysfunction and contributes to the pathogenesis of pre- eclampsia” and our hypothesis will be tested by the following three specific aims. Specific Aim 1: We will assess whether HUVEC obtained from mothers with pre-eclampsia (PE-HUVEC) synthesize and release less GABA when compared to those obtained from mothers with normal pregnancy. Specific Aim 2: We will compare the role of GABA in maintaining the normal functions of HUVEC obtained from normal pregnancies with relation to free fatty acid (FFA) oxidation, pyruvate oxidation, ATP synthesis, regulation of adhesion molecules expression and reactive oxygen species (ROS) generation and how decreased synthesis of GABA in PE-HUVEC affects these processes to cause endothelial cell dysfunction. Specific Aim 3: (a) We will assess the effects of the endogenous GABA synthesis inhibitor LMG, which is high in PE-HUVEC, on some of the GABA mediated functions of NP-HUVEC and HAEC as assessed under specific aim 2 and (b) we will quantify the levels of GABA and LMG in the cord and maternal blood of normal pregnancy and correlate this with the cord and maternal levels in preeclamptic pregnancy.