MODULATION OF CHOROID PLEXUS CHOLINE TRANSPORT BY METALS

金属对脉络丛胆碱转运的调节

• 批准号: 6518179
• 负责人: Alice Renee Villalobos
• 金额: $ 23.93万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-05-09 至 2004-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6518179
• 关键词: active transport; animal tissue; biological transport; cadmium; choline; heat shock proteins; laboratory rat; membrane permeability; metal metabolism; metal poisoning; neurotransmitter transport; radiotracer; tissue /cell culture; zinc

The long term goal of this research is to establish an experimental system for predicting physicochemical stress-modulation of choline transport across the cerebrospinal fluid (CSF)-blood barrier, i.e., the choroid plexus epithelium. The objective of this proposal is to characterize modulation of choroid plexus choline transport by zinc and cadmium as a means to predict the potential for heavy metals to alter choline availability in the brain. Choline is a polar constituent of membrane phospholipids and an immediate precursor to acetylcholine, the neurotransmitter for central cholinergic pathways crucial in neural control of behaviors such as sleep-wake cycling and learning/memorization. Choline availability is also critical for normal brain development; deficiency in fetal or neonate rats results in developmental and behavioral abnormalities and learning/memory deficits that may persist in the adult. Symptoms of heavy metal toxicity in neonate animals and children include significant reduction in learning/memory skills and behavioral disorders. Cadmium and other metals may directly inhibit central cholinergic neuron activity. However, these metals may also compromise cholinergic activity by reducing choline availability. Heavy metal exposure has been shown to reduce choline levels in the midbrain. Metals such as cadmium and zinc accumulate within the choroid plexus, which actively transports choline out of the brain. These heavy metals may stimulate choroidal choline transport, enhancing choline removal and decreasing its availability in the brain. The proposed studies will test the hypothesis: Choline is actively transported across the CSF-blood barrier and, therefore, modulation of this active transport process by a chemical stress, i.e., exposure to heavy metals, may alter choline availability in the brain. This hypothesis will be directly tested using a primary culture system of choroidal plexus epithelial cells from neonate rats. Radiotracer, molecular biology, immunochemistry and fluorescence microscopy techniques will be used to meet the following specific aims: i.) characterize cellular mechanisms that mediate choline transport across the CSF-blood barrier; ii.) examine zinc-induced modulation and thermotolerance of choroidal choline transport; iii.) characterize heat-shock protein- dependent modulation of choline transport by cadmium. A greater understanding of the energetics and modulation of choline transport across the CSF-blood barrier may permit more effective management and treatment of metal neurotoxicity and other central nervous disorders that involve changes in free choline levels, such as organophosphate poisoning.

这项研究的长期目标是建立一个实验系统，用于预测胆碱跨脑脊液（CSF）-血液屏障（即脉络丛上皮）转运的物理化学应激调节。该提案的目的是表征锌和镉对脉络丛胆碱转运的调节，作为预测重金属改变大脑中胆碱可用性的潜力的手段。 胆碱是膜磷脂的极性成分，也是乙酰胆碱的直接前体，乙酰胆碱是中枢胆碱能通路的神经递质，对于睡眠-觉醒循环和学习/记忆等行为的神经控制至关重要。 胆碱的可用性对于正常的大脑发育也至关重要。胎儿或新生大鼠的缺乏会导致发育和行为异常以及学习/记忆缺陷，这些缺陷可能在成年大鼠中持续存在。 新生动物和儿童的重金属毒性症状包括学习/记忆能力显着下降和行为障碍。 镉和其他金属可能直接抑制中枢胆碱能神经元的活动。 然而，这些金属也可能通过降低胆碱的利用率来损害胆碱能活性。 重金属暴露已被证明会降低中脑的胆碱水平。 镉和锌等金属积聚在脉络丛内，脉络丛主动将胆碱转运出大脑。 这些重金属可能会刺激脉络膜胆碱运输，增强胆碱的清除并降低其在大脑中的可用性。拟议的研究将检验以下假设：胆碱主动转运穿过脑脊液血屏障，因此，通过化学应激（即接触重金属）调节这种主动转运过程可能会改变大脑中胆碱的可用性。 该假设将使用新生大鼠脉络丛上皮细胞的原代培养系统直接进行测试。 放射性示踪剂、分子生物学、免疫化学和荧光显微镜技术将用于实现以下具体目标：i.) 表征介导胆碱跨脑脊液-血液屏障转运的细胞机制； ii.) 检查锌诱导的脉络膜胆碱运输的调节和耐热性； iii.) 表征镉对胆碱转运的热休克蛋白依赖性调节。 更好地了解胆碱跨脑脊液-血屏障转运的能量和调节可能有助于更有效地管理和治疗金属神经毒性和其他涉及游离胆碱水平变化的中枢神经疾病，例如有机磷中毒。

项目成果

Stress-induced stimulation of choline transport in cultured choroid plexus epithelium exposed to low concentrations of cadmium.

• DOI: 10.1152/ajpregu.00252.2013
• 发表时间: 2014-03
• 期刊: American journal of physiology. Regulatory, integrative and comparative physiology
• 作者: R. Young;A. Villalobos