Negative impacts of microcystin-LR and glyphosate on zebrafish intestine: Linked with gut microbiota and microRNAs?

• Published in: Environmental pollution (1987) 2021-10, Vol.286, p.117685, Article 117685
• Main Authors: Ding, Weikai, Shangguan, Yingying, Zhu, Yuqing, Sultan, Yousef, Feng, Yiyi, Zhang, Bangjun, Liu, Yang, Ma, Junguo, Li, Xiaoyu
• Format: Article
• Language: English
• Subjects: Animals; Danio rerio; Gastrointestinal Microbiome; Glycine - analogs & derivatives; Glyphosate; Gut microbiota; Humans; Intestines; Marine Toxins; Microbiota; Microcystin-LR; Microcystins - toxicity; MicroRNAs; Potential hazard; Water Pollutants, Chemical - toxicity; Zebrafish
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2021.117685

Microcystin-LR (MC-LR) and glyphosate (GLY) have been classified as a Group 2B and Group 2A carcinogens for humans, respectively, and frequently found in aquatic ecosystems. However, data on the potential hazard of MC-LR and GLY exposure to the fish gut are relatively scarce. In the current study, a subacute toxicity test of zebrafish exposed to MC-LR (35 μg L−1) and GLY (3.5 mg L−1), either alone or in combination was performed for 21 d. The results showed that MC-LR or/and GLY treatment reduced the mRNA levels of tight junction genes (claudin-5, occludin, and zonula occludens-1) and altered the levels of diamine oxidase and D-lactic, indicating increased intestinal permeability in zebrafish. Furthermore, MC-LR and/or GLY treatment remarkably increased the levels of intestinal IL-1β and IL-8 but decreased the levels of IL-10 and TGF-β, indicating that MC-LR and/or GLY exposure induced an inflammatory response in the fish gut. MC-LR and/or GLY exposure also activated superoxide dismutase and catalase, generally upregulated the levels of p53, bax, bcl-2, caspase-3, and caspase-9, downregulated the levels of caspase-8 and caused notable histological injury in the fish gut. Moreover, MC-LR and/or GLY exposure also significantly altered the microbial community in the zebrafish gut and the expression of miRNAs (miR-146a, miR-155, miR-16, miR-21, and miR-223). Chronic exposure to MC-LR and/or GLY can induce intestinal damage in zebrafish, and this study is the first to demonstrate an altered gut microbiome and miRNAs in the zebrafish gut after MC-LR and GLY exposure. [Display omitted] •Single or co-exposure of MC-LR and GLY could cause gut injury in zebrafish.•GLY has a greater effect on gut microbiota than combined MC-LR and GLY.•MC-LR and GLY didn't exhibited significant synergic or antergic interactions.•miRNAs may play pivotal role in the toxicity of MC-LR or/and GLY exposure.