Abstract：
Microplastics (MPs) usually appear in the aquatic environment as complex pollutants with other environmental pollutants, such as levofloxacin (LVFX). After 45-day exposure to LVFX and MPs with different particle sizes at environmental levels, we measured the weight, snout-to-vent length (SVL), and development stages of Rana nigromaculata. Furthermore, we analyzed proteins and genes related to immune system and thyroid axis regulation, intestinal histological, and bioaccumulation of LVFX and MPs in the intestine and brain to further explore the toxic mechanism of co-exposure. We found MPs exacerbated the effect of LVFX on growth and development, and the order of inhibitory effects is as follows: LVFX-MP3>LVFX-MP1>LVFX-MP2. 0.1 and 1 μm MP could penetrate the blood-brain barrier, interact with LVFX in the brain, and affect growth and development by regulating thyroid axis. Besides, LVFX with MPs caused severer interference on thyroid axis compared with LVFX alone. However, 10 μm MP was prone to accumulating in the intestine, causing severe histopathological changes, interfering with the intestinal immune system and influencing growth and development through immune enzyme activity. Thus, we concluded that MPs could regulate the thyroid axis by interfering with the intestinal immune system.
摘要：
微塑料(MPs)通常作为与其他环境污染物的复合污染物出现在水生环境中,如左氧氟沙星（LVFX）。在环境水平下暴露于不同粒径的LVFX和MPs45天后，我们测量了重量，鼻子到通风口的长度（SVL），黑斑蛙的发育阶段。此外，我们分析了与免疫系统和甲状腺轴调节相关的蛋白质和基因，肠道组织学，LVFX和MPs在肠道和大脑中的生物蓄积，进一步探讨共暴露的毒性机制。我们发现国会议员加剧了LVFX对增长和发展的影响，抑制作用的顺序如下:LVFX-MP3>LVFX-MP1>LVFX-MP2。0.1和1μmMP可以穿透血脑屏障，与大脑中的LVFX相互作用，并通过调节甲状腺轴影响生长发育。此外,与单独使用LVFX相比，使用MPs的LVFX对甲状腺轴的干扰更严重。然而,10μmMP容易在肠道中积累，导致严重的组织病理学变化，通过免疫酶活性干扰肠道免疫系统，影响生长发育。因此，我们的结论是，MPs可以通过干扰肠道免疫系统来调节甲状腺轴。
