MECHANISMS RESPONSIBLE FOR COGNITIVE IMPAIRMENT CAUSED BY EXPOSURE TO PCBS

已知多氯联苯对神经系统有多种影响，但其中一种 其中最严重的是认知潜力的下降 据报道，儿童的身体负担增加。 目标 这项调查的目的是确定多氯联苯是否改变了各种 动物模型系统中已知重要的神经元过程 在学习和记忆方面。 我们建议使用急性和慢性暴露于 多氯联苯1248和四种单一的多氯联苯同系物，以及 电生理学和流式细胞术技术。 主要的假设是 被测试的是多氯联苯将减少或阻止长期的过程 增强（LTP），这是一个最好的可用模型系统， 学习和记忆。 如果是这样，我们的初步结果 如果我认为是，我们将尝试确定作用机制 责任 利用电生理记录，我们将研究突触 在两个海马回路，谢弗侧支-CA 1 途径和苔藓纤维-CA 3途径。 我们将调查正常 递质释放和突触后反应和几个指标 神经元可塑性[强直电位增强（PTP，LTP，成对脉冲 增强作用、佛波酯诱导的增强作用]。 我们希望能找到一个 对这些复杂反应中的一个或多个采取选择性行动，如果是这样，我们 将试图确定其机制。 我们将研究对 对特定神经递质受体（N-甲基-D-天冬氨酸， 乙酰胆碱），各种激酶，包括蛋白激酶C和钙 进入和/或释放 为了直接监测钙，我们将使用 小脑颗粒神经元的流式细胞仪研究，并确定 PCBs是否对钙通量有直接影响，以及 多氯联苯对五种不同钙离子触发的钙离子进入或释放的影响 途径。 我们将监测多氯联苯对膜电位变化的影响 以及通过不同途径在细胞中产生自由基。 如果 如果发现影响，我们将试图确定哪些同系物是 负责任，是否通过干扰甲状腺介导的影响 功能或多巴胺耗竭，或者是否有某种机制， 责任

PCBs are known to have a variety of effects on the nervous system, but one of the potentially most serious is the decrement in cognitive potential that has been reported in children having elevated body burdens. The goal of this investigation is to determine whether PCBs alter a variety of neuronal processes in a animal model system that are known to be important in learning and memory. We propose to use acute and chronic exposure to Aroclor 1248 and four single PCB congeners, and a combination of electrophysiologic and flow cytometric techniques. The major hypothesis to be tested is the PCBs will reduce or block the process of long-term potentiation (LTP), which is one of the best available model systems for learning and memory. If this is the case, and our preliminary results suggest that it is, we will attempt to determine the mechanism(s) of action responsible. Using electrophysiological recordings, we will study synaptic transmission in two hippocampal circuits, the Schaffer collateral-CA1 pathway and the mossy fiber-CA3 pathway. We will investigate normal transmitter release and post-synaptic responses and several indicators of neuronal plasticity [pot-tetanic potentiation (PTP, LTP, paired pulse potentiation, phorbol ester-induced potentiation]. We expect to find a selective action on one or more of these complex responses, and if so, we will attempt to determine the mechanism. We will investigate effects on responses to specific neurotransmitter receptors (N-methyl-D-aspartate, acetylcholine), various kinases, including protein kinase C and calcium entry and/or release. In order to directly monitor calcium we will use cerebellar granule neurons studies in a flow cytometer, and determine whether there are direct effects of PCBs on calcium flux, as well as effects of PCBs on calcium entry or release triggered by five different pathways. We will monitor effects of PCBs on membrane potential changes and on generation of free radicals in the cells by different pathways. If effects are found, we will attempt to determine which congeners are responsible, whether the effects are mediated via interference with thyroid function or dopamine depletion, or whether some whether mechanism is responsible.