The gut microbiome and glyphosate neurotoxicity

摘要 该申请解决了神经毒理学中的一个重大空白，即肠道微生物组的作用。微生物组 通过其在广泛的宿主中的关键作用， 相关功能。越来越多的证据表明，失调的肠道微生物菌群显著有助于 各种人类疾病。事实上，肠道微生物组很容易受到外部因素的影响， 关于外源性物质对肠道菌群作用的问题。草甘膦除草剂，如 农达是世界上使用最广泛的杀虫剂。甘草酸作用于植物中的莽草酸途径 通过抑制5-烯醇式莽草酸-3-磷酸合酶（EPSPS）， 芳香族氨基酸，导致植物死亡。由于莽草酸途径在哺乳动物中不存在， 人们普遍认为草甘膦对人类是安全的。然而，草甘膦的不利影响，包括 在哺乳动物中的神经毒性已经有充分的记录。特别重要的是，许多功能重要的肠道 啮齿动物和人类的细菌确实有莽草酸途径，这表明草甘膦可能会扰乱 肠道微生物组和相关的莽草酸途径来改变芳香族氨基酸、前体 单胺神经递质的作用值得注意的是，神经行为障碍通常以失调为特征， 芳香族氨基酸和神经递质通路。然而，肠道和胃肠道之间的功能性相互作用 微生物组和草甘膦暴露，特别是在与人类暴露相关的剂量下， 呢本申请的目的是确定草甘膦对肠道的影响 微生物组和草甘膦破坏的微生物组在引起宿主神经毒性中的作用。我们将 分三个阶段解决问题，首先描述肠道微生物组的变化， 16 S rRNA测序，然后使用鸟枪宏基因组学和代谢组学来绘制代谢改变。 最后，我们将确定草甘膦干扰肠道微生物组如何因果地改变代谢组，莽草酸和 相关通路、神经递质和神经行为表型。我们 拟议的研究意义重大，代表了草甘膦研究的新前沿，因为我们专注于肠道 微生物组扰动作为其神经毒性的新机制。在这个项目完成后，我们的 期望这些结果将为未来的研究奠定基础，旨在扩大我们的理解， 草甘膦神经毒性和肠道微生物组在暴露于草甘膦引起的人类疾病中的作用， 历史上使用最广泛最多的除草剂

ABSTRACT This application addresses a significant gap in neurotoxicology, i.e. the role of gut microbiome. The microbiome of the human intestinal tract has a profound effect on human health through its key role in a wide range of host- related functions. Mounting evidence indicates that dysregulated gut microflora contribute significantly to a variety of human diseases. The fact that the gut microbiome can be readily affected by external factors raises questions regarding the role of xenobiotics on intestinal microflora. Glyphosate-based herbicides, such as Roundup, are the most widely used pesticides worldwide. Glyphosate acts on the shikimate pathway in plants through inhibiting 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), which disrupts the synthesis of aromatic amino acids, leading to plant death. Since the shikimate pathway does not exist in mammals, it is generally believed that glyphosate would be safe in humans. However, glyphosate adverse effects, including neurotoxicity, in mammals has been well documented. Of particular importance, many functionally important gut bacteria of rodents and humans do have the shikimate pathway, highlighting that glyphosate may perturb the gut microbiome and associated shikimate pathway to alter the homeostasis of aromatic amino acids, precursors of monoamine neurotransmitters. Of note, neurobehavioral disorders are often characterized with dysregulated aromatic amino acids and neurotransmitter pathways. However, the functional interaction between the gut microbiome and glyphosate exposure, especially at doses relevant to human exposure, is largely unexplored yet. The objective of this particular application is to define the impact of glyphosate on disturbing the gut microbiome and the role of glyphosate-disrupted microbiome in provoking neurotoxicity in the host. We will approach the problems in three stages by first characterizing the changes in the gut microbiome profiles with 16S rRNA sequencing, and then using shotgun metagenomics and metabolomics to map metabolic alterations. Lastly, we will define how glyphosate-perturbed gut microbiome causatively alters metabolome, shikimate and relevant pathways, neurotransmitters and neurobehavioral phenotypes via microbiome transplantation. Our proposed study is significant and represents a new frontier in glyphosate research because we focus on gut microbiome perturbation as a novel mechanism of its neurotoxicity. At the completion of this project, it is our expectation that these results will lay a foundation for future studies aiming at expanding our understanding of glyphosate neurotoxicity and the role of gut microbiome in human diseases caused by exposure to glyphosate, the most widely and heavily used herbicide in history.