Department of Medicine, Faculty of Health Sciences. Universitat Jaume I, Avenida de Vicent Sos Baynat s/n, 12071, Castellón de la Plana, Spain.
Faculty of Nursing and Podiatry, Universitat de València, C/Menendez Pelayo S/n, 46010, València, Spain; Epidemiology and Environmental Health Joint Research Unit, FISABIO-Universitat Jaume I-Universitat de Valencia, Av. Catalunya 21, 46020, València, Spain; Spanish Consortium for Research on Epidemiology and Public Health (CIBERESP), Av. Monforte de Lemos, 3-5. Pabellón 11, 28029, Madrid, Spain.
Environ Pollut. 2024 May 1;348:123732. doi: 10.1016/j.envpol.2024.123732. Epub 2024 Mar 8.
The gut-brain axis is a crucial interface between the central nervous system and the gut microbiota. Recent evidence shows that exposure to environmental contaminants, such as heavy metals, can cause dysbiosis in gut microbiota, which may affect the gut-brain communication, impacting aspects of brain function and behavior. This systematic review of the literature aims to evaluate whether deleterious effects on brain function due to heavy metal exposure could be mediated by changes in the gut microbiota profile. Animal studies involving exposure to heavy metals and a comparison with a control group that evaluated neuropsychological outcomes and/or molecular outcomes along with the analysis of microbiota composition were reviewed. The authors independently assessed studies for inclusion, extracted data and assessed risk of bias using the protocol of Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) for preclinical studies. A search in 3 databases yielded 16 eligible studies focused on lead (n = 10), cadmium (n = 1), mercury (n = 3), manganese (n = 1), and combined exposure of lead and manganese (n = 1). The animal species were rats (n = 7), mice (n = 4), zebrafish (n = 3), carp (n = 1) and fruit fly (n = 1). Heavy metals were found to adversely affect cognitive function, behavior, and neuronal morphology. Moreover, heavy metal exposure was associated with changes in the abundance of specific bacterial phyla, such as Firmicutes and Proteobacteria, which play crucial roles in gut health. In some studies, these alterations were correlated with learning and memory impairments and mood disorders. The interplay of heavy metals, gut microbiota, and brain suggests that heavy metals can induce direct brain alterations and indirect effects through the microbiota, contributing to neurotoxicity and the development of neuropsychological disorders. However, the small number of papers under review makes it difficult to draw definitive conclusions. Further research is warranted to unravel the underlying mechanisms and evaluate the translational implications for human health.
肠道-脑轴是中枢神经系统与肠道微生物群之间的重要接口。最近的证据表明，暴露于环境污染物（如重金属）会导致肠道微生物群失调，这可能会影响肠道-脑通讯，影响大脑功能和行为的各个方面。本系统综述旨在评估重金属暴露对大脑功能的有害影响是否可以通过肠道微生物群谱的变化来介导。综述了涉及暴露于重金属的动物研究，并与对照组进行了比较，对照组评估了神经心理学结局和/或分子结局，以及微生物群落组成的分析。作者使用实验室动物实验 SYRCLE（SYRCLE for preclinical studies）方案独立评估研究纳入情况、提取数据并评估偏倚风险。在 3 个数据库中进行了搜索，得到了 16 项符合条件的研究，重点关注铅（n=10）、镉（n=1）、汞（n=3）、锰（n=1）和铅与锰联合暴露（n=1）。动物物种为大鼠（n=7）、小鼠（n=4）、斑马鱼（n=3）、鲤鱼（n=1）和果蝇（n=1）。重金属被发现会对认知功能、行为和神经元形态产生不利影响。此外，重金属暴露与特定细菌门的丰度变化有关，如厚壁菌门和变形菌门，它们在肠道健康中起着至关重要的作用。在一些研究中，这些变化与学习和记忆障碍以及情绪障碍有关。重金属、肠道微生物群和大脑之间的相互作用表明，重金属可以通过直接改变大脑和间接通过微生物群来诱导神经毒性和神经心理障碍的发展。然而，综述中的论文数量较少，难以得出明确的结论。需要进一步的研究来揭示潜在的机制，并评估对人类健康的转化意义。
