MECHANISMS OF DEVELOPMENTAL LEAD NEUROTOXICITY

发育性先导神经毒性的机制

• 批准号: 2749666
• 负责人: Janusz Bogdan Suszkiw
• 金额: $ 26.29万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-04-01 至 2000-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2749666
• 关键词: acetylcholine; apoptosis; brain septal area; choline acetyltransferase; denervation; developmental neurobiology; electrophysiology; gene expression; genetic regulatory element; growth factor receptors; hippocampus; histopathology; immunocytochemistry; laboratory rat; lead poisoning; membrane potentials; neurotoxicology; neurotrophic factors; newborn animals; voltage /patch clamp

DESCRIPTION: Asymptomatic neurotoxicity of low-level, environmental lead (Pb) exposure in human fetus, infants, and young children poses a significant public health problem. Epidemiological and experimental studies indicate that lead exposure during development causes lasting cognitive and behavior impairments. The Center for Disease Control estimates 3 million U.S. children have lead concentrations above the danger level of 10 micrograms per decaliter of blood. The long-term goal of this research is to understand the biology of developmental lead-induced brain injury and ultimately develop strategies to ameliorate its consequences. Our studies to date indicate that exposure of perinatal rat to low-doses of Pb selectively compromises the survival and function of cholinergic septohippocampal neurons, resulting in lasting denervation-like effects in the hippocampus. The current project will characterize the cellular and molecular basis of the lesion and its long-term effects on hippocampal physiology. 1. Histo-morphometric analysis will be carried out to correlate the extent of Pb-induced loss of ChAT-immunoreactive neurons in the septum with the reduction of the AChE-positive fiber density and cholinergic presynaptic markers in the rat hippocampus in vivo. The aim of these experiments is to determine the relationship between Pb exposure dosage, the extent of cholinergic denervation, and subsequent recovery (reinnervation). A related issue that will be examined in the course of these studies concerns the effect of the sympathohippocampal ingrowth on the extent of functional recovery. 2. Electrophysiological analysis of hippocampal electrical activity will be carried out to obtain neurophysiological correlates of Pb-induced cholinergic deficit and its reversal. The functional integrity of cholinergic septohippocampal pathway will be assessed by measuring changes in the atropine-sensitive, type 2 hippocampal theta rhythm. Patch clamp recordings from acutely isolated septal neurons will be employed to analyze the effect of in vivo Pb exposure on the electrophysiology of identified septohippocampal projections neurons. The neurons will be identified by retrograde labeling and immunocytochemical staining. 3. Molecular and cell biological techniques win be employed to test the hypothesis that differential vulnerability of septal cholinergic neurons to Pb results from the disruption of nerve growth factor (NGF)-dependent regulation of cholinergic gene expression and cell survival. Specifically, we will determine if Pb (a) alters expression of the low- and high-affinity receptors (p75 and pl4Otrk), (b) alters ChAT protein and mRNA expression by interfering with NGF-responsive regulatory elements of the rat ChAT gene, and (c) induces cholinergic neuron apoptosis by disrupting the cell survival functions of NGF.

描述：低级，环境铅的无症状神经毒性 （PB）人类胎儿，婴儿和幼儿的暴露会带来A 重大的公共卫生问题。 流行病学和实验性 研究表明，发育过程中的铅暴露会导致持久 认知和行为障碍。 疾病控制中心 估计有300万美国儿童的铅浓度高于 每张贴符的血液的危险水平为10微克。 长期 这项研究的目标是了解发展的生物学 铅引起的脑损伤，并最终制定策略 改善其后果。 迄今为止我们的研究表明暴露 围产期大鼠至低剂量的PB有选择地损害生存 胆碱能神经元神经元的功能，导致 海马中的持久神经神经样作用。 当前项目 将表征病变及其的细胞和分子基础 对海马生理的长期影响。 1。将进行历史图分析以将 隔膜中PB引起的CHAT免疫反应性神经元的丧失程度 随着ACHE阳性纤维密度和胆碱能的降低 体内大鼠海马的突触前标记。 这些目的 实验是确定PB暴露剂量之间的关系， 胆碱能神经治疗的程度以及随后的恢复 （重新支配）。 课程中将检查的相关问题 这些研究涉及交感神经内的影响 在功能恢复的范围内。 2。海马电活动的电生理分析将 进行以获得PB诱导的神经生理学相关性 胆碱能赤字及其逆转。 功能完整性 将通过测量评估胆碱能septohappocampal途径 阿托品敏感的2型海马theta节奏的变化。 来自急性分离的间隔神经元的斑块夹记录将是 用于分析体内PB暴露对 已鉴定出的Septohampocampal突显神经元的电生理学。 神经元将通过逆行标记和 免疫细胞化学染色。 3。用于测试分子和细胞生物技术胜利 假设间隔胆碱能神经元的差异脆弱性 由神经生长因子（NGF）依赖性的破坏引起的PB 调节胆碱能基因表达和细胞存活。 具体而言，我们将确定pb（a）是否改变了低 - 的表达 和高亲和力受体（P75和PL4OTRK），（b）改变聊天蛋白 通过干扰NGF响应​​调节来表达mRNA 大鼠聊天基因的元素，（c）诱导胆碱能神经元 通过破坏NGF的细胞存活功能来凋亡。