基于多巴胺介导的信号通路探讨壬基酚诱发秀丽线虫行为障碍的分子机制

Nonylphenol (NP) is a common endocrine disruptor in the environment which has many characteristics, such as persistence, accumulation, hysteresis and low dose effect. Thus, it is a serious threat to the survival and reproduction of human beings. However, there is no risk assessment of nonylphenol in China, and the mechanism of neurobehavioral damage induced by low dose nonylphenol exposure is not clear. Caenorhabditis elegans is one of the most important model organisms for the study of the regulation mechanism of many complex life phenomena, such as neural development and learning-memory. The aim of this study is to investigate the mechanism of locomotor defects induced by low dose NP exposure in C.elegans. Firstly, nonylphenol induced behavior alteration including lifespan, predation behavior, locomotion behavior and learning-memory ability in wild-type worms will be detected. Then dopamine neuron gene deficient nematodes are used to confirm whether dopamine is involved in nonylphenol induced locomotor defects. Whether the activation of dopamine contributes to modulate p38-MAPK and daf-16 signaling pathways as a result of controlling neurobehavior is further determined via related mutants. Taken together, this research will be of great value in explaining the potential molecular mechanism of low dose nonylphenol exposure induced neurological damage, and explaining the pathogenesis of neurodegenerative diseases. Meanwhile, it provides evidence for risk assessment and limitation standard establishment of nonylphenol in China.

壬基酚是一种广泛存在于环境中的内分泌干扰物，具有持久性、蓄积性、滞后性、低剂量-效应等特点，对人类的生存和繁衍构成严重的威胁。而我国还没有关于壬基酚的风险评估，同时低剂量壬基酚暴露诱发神经行为损伤的机制尚不清楚。秀丽线虫是研究神经发育和学习记忆等多种复杂生命现象调控机制的重要模式生物之一。本项目拟从寿命实验、捕食行为、运动行为、学习记忆行为观察壬基酚对野生型线虫的神经行为损害作用；进一步基于多巴胺信号，以多巴胺基因缺陷型线虫为模型研究壬基酚引起神经系统损伤的分子机制；在此基础上，以p38-MAPK和daf-16信号通路为切入点，利用相关突变体线虫探讨多巴胺介导壬基酚诱发行为障碍的机制。本项目的完成有利于阐述低剂量壬基酚暴露引起神经系统损伤的潜在分子机制，有助于揭示神经退行性疾病的发病机理，同时可为我国开展壬基酚的风险评估与限量标准制定等提供依据。

壬基酚（Nonylphenol，简称NP）是环境中普遍存在的一种内分泌干扰物，能够引起内分泌失调，改变神经、免疫和生殖发育系统等的正常调控功能，然而其诱导神经损伤的分子机制不明确。秀丽隐杆线虫是研究神经发育和学习记忆等多种复杂生命现象调控机制的重要模式生物之一。本项目以秀丽线虫为模型，研究了壬基酚的神经毒性效应，并阐明了其相关的分子机制。研究发现壬基酚暴露可以缩短野生型线虫N2的寿命、影响线虫的捕食行为和学习运动行为，说明壬基酚对秀丽线虫具有神经行为毒性效应。壬基酚暴露引起野生型线虫内活性氧生成增加，超氧化物歧化酶活性降低、丙二醛含量升高，说明壬基酚能够诱导线虫发生氧化应激损伤。通过对野生型线虫内p38-MAPK信号通路和daf-16信号通路相关基因的检测，发现p38-MAPK信号通路和daf-16信号通路参与了壬基酚对线虫神经行为的调控，并且该结果通过壬基酚对p38-MAPK信号通路和daf-16信号通路相关突变体的行为指标效应，得到了进一步的证实。以多巴胺神经元基因缺陷型cat-1线虫、5-羟色胺神经元基因缺陷型tph-1线虫为模型，观察壬基酚对标准品回补前后的cat-1线虫和tph-1线虫行为指标的影响，发现多巴胺和5-羟色胺神经递质参与了壬基的神经毒性效应。进一步通过检测cat-1线虫和tph-1线虫内p38-MAPK信号通路和daf-16信号通路相关基因以及抗性基因的表达，发现壬基酚通过多巴胺或羟色胺参与调控的p38-MAPK信号通路和daf-16信号通路以及抗性基因的表达发挥秀丽线虫神经行为损伤效应。因此，本研究明确了壬基酚诱导神经毒性作用的分子机制，发现了相关的调控基因和作用靶点。该研究结果可为环境中壬基酚的风险评估以及环境和食品中壬基酚的控制标准提供依据。