A non-invasive system for monitoring neurotoxicity in animal models

大脑和神经系统不断地暴露在来自环境和药物中的大量潜在有害化学物质中。为了将风险降至最低，需要对新药和环境化学品的神经毒性潜力进行评估，作为分级毒性测试的结构化过程的一部分。然而，目前的方法可能无法确定低水平的神经毒性，特别是在发生在不可预见的(靶外)的情况下。大脑的各个区域。鉴于最近的流行病学证据表明，在帕金森-S病等神经退行性疾病中，环境神经毒素的有害影响可能要在暴露多年后才显现出来，因此这一点特别重要。因此，开发能够检测低水平神经毒性的生物标记物显然是一个尚未得到满足的需求。为了实现这一目标，我们将开发一种新型的基因工程小鼠模型，在该模型中，分子记者连接到关键应激传感器基因的调控序列，这些基因可以被各种化学毒素和致癌物激活。当压力基因被激活时，其中一个报告，生物活性不活跃的人绒毛膜促性腺激素β链，被排泄到血液和随后的尿液中，而第二个报告仍然定位于激活传感器基因的细胞。任何引起毒性的化学或病理条件都将导致毒性的实时信号？这可以通过对排泄物记者的尿液分析来监测。然后，可以通过为现场记者染色大脑切片来识别有毒侮辱的位置。这种方法的成功开发将代表着神经毒性测试的重大进步。由于这些毒性传感器在细胞死亡之前被激活，我们预计应该比传统组织学技术更早地检测到报告，并使用较低剂量的测试化合物。使用可排泄的报告作为非侵入性毒性生物标记物，可以在单个动物身上进行时程或剂量递增研究，从而大大减少这些研究所需的动物数量。表达原位报告的细胞的可视化使用现有的生化方法，并可进行自动化分析。这种更高的吞吐量将允许对神经毒性进行更系统的分析，并将突出低水平毒性的领域，即使它们发生在哪里？偏离目标？

The brain and nervous system are continuously exposed to a vast array of potentially harmful chemicals from the environment and in medicines. To minimise the risk, new medicines and environmental chemicals are required to be assesed for their neurotoxic potential as part of a structured process of tiered toxicity testing. However, current methods may fail to identify low-levels of neurotoxicity, particularly where it occurs in unforeseen (?off-target?) areas of the brain. This is of particular significance in the light of recent epidemiological evidence that in neurodegenerative disorders such as Parkinson?s disease, the harmful effects of environmental neurotoxins may only become apparent many years after exposure. Thus, there is a clear unmet need to develop biomarkers that can detect low-level neurotoxicity.To achieve this goal we will develop a novel genetically engineered mouse model in which molecular reporters are attached to the regulatory sequences of key stress sensor genes that are activated by a wide variety of chemical toxins and carcinogens. Upon activation of the stress-gene, one of these reporters, the biologically inactive beta-chain of human chorionic gonadotrophin, is excreted into the blood and subsequently the urine, while the second reporter remains localised to the cells in which the sensor gene is activated. Any chemical or pathological condition that causes toxicity will result in a real-time ?signal of toxicity? that can be monitored by urine analysis for the excretable reporter. The site of toxic insult can then be identified by staining brain sections for the in situ reporter.The successful development of this approach would represent a significant advance in neurotoxicity testing. As these toxicity sensors are activated prior to cell death we anticipate that the reporters should be detected earlier and at lower doses of test compound than required for conventional histological techniques. The use of the excretable reporter as a non-invasive toxicity biomarker permits time-course or dose escalation studies to be performed in individual animals, thereby reducing considerably the number of animals required for these studies. Visualisation of cells expressing the in situ reporter uses established biochemical methods and is amenable to automated analysis. This higher throughput would permit a more systematic analysis of neurotoxicity and would highlight areas of low-level toxicity, even where they occur, ?off-target?