5-HT Reuptake in SERT Knockout Mice by Voltammetry

本研究旨在应用“快速”电化学方法测定血清素转运蛋白敲除小鼠脑组织中血清素的实时再摄取和释放。这些小鼠的产生是为了更清楚地了解血清素转运体在规范行为、焦虑和情绪障碍中的作用。血清素转运蛋白敲除小鼠对3,4-亚甲基二氧甲基苯丙胺（一种常见的滥用药物）的反应显示自发性焦虑样行为升高，运动激活减少。据推测，这些表型变化直接归因于血清素转运功能的长期下降，最终导致血清素能系统及其突触后靶点的神经适应性变化。迄今为止研究的许多神经化学和行为参数表明，携带一个功能拷贝的5 -羟色胺转运基因的小鼠发生了中等水平的变化。然而，通过[3H]血清素摄取初步评估的转运蛋白功能在杂合子敲除小鼠中似乎没有改变。因此，我们假设经典放射化学方法对血清素摄取的表征不能提供必要的时间分辨率来检测摄取过程动力学中的重要变化。本研究将：(1)利用高速计时电流法评估血清素转运蛋白敲除小鼠突触体的血清素摄取动力学；(2)利用快速扫描循环伏安法表征5 -羟色胺转运蛋白敲除小鼠切片制剂中特定脑区5 -羟色胺的再摄取和释放动力学。我们的目的是回答转运蛋白表达的中间变化是否会导致转运蛋白功能的显著改变。这一建议代表了伏安技术在转基因小鼠模型中表征血清素能神经传递变化的新应用。

This proposal is concerned with the application of "fast" electrochemical methods for the determination of real-time serotonin reuptake and release in brain tissue derived from serotonin transporter knockout mice. These mice were produced to gain a clearer understanding of the role of the serotonin transporter in normative behavior, and in anxiety and mood disorders. Serotonin transporter knockout mice display elevations in spontaneous anxiety-like behavior and decreases in locomotor activation in response to 3,4- methylenedioxymethamphetamine (MDMA), a popular drug of abuse. It is hypothesized that these alterations in phenotype are directly attributable to long-term decreases in serotonin transporter function, which ultimately result in neuroadaptive changes in the serotonergic system and its postsynaptic targets. Many of the neurochemical and behavioral parameters studied to date show intermediate levels of change in mice bearing one functional copy of the serotonin transporter gene. However, transporter function initially assessed by [3H]serotonin uptake appears unaltered in heterozygote knockout mice. Therefore, we hypothesize that the characterization of serotonin uptake by classical radiochemical methods does not provide the temporal resolution necessary to detect important variations in the kinetics of the uptake process. The research described will: (1) Evaluate the kinetics of serotonin uptake using high-speed chronoamperometry in synaptosomes derived from serotonin transporter knockout mice; and (2) Characterize the dynamics of serotonin reuptake and release in specific brain regions in slice preparations from serotonin transporter knockout mice using fast scan cyclic voltammetry. We aim to answer the question of whether intermediate changes in transporter expression lead to significant modifications in transporter function. This proposal represents the novel application of voltammetric techniques to the characterization of changes in serotonergic neurotransmission in transgenic mouse models.