Effects of oral exposure to nanoplastics on inflammatory response and autonomic nervous function of the area postrema

本研究探讨长期口服纳米塑料是否会改变大脑无血脑区细胞和分子特征及其生理功能。5周龄雄性Wistar大鼠（每组6只）每天喂食带正电荷或负电荷的聚苯乙烯纳米颗粒（NPs）（直径50 nm， 12.5 mg/kg体重），持续2个月。为了证实循环NPs向AP的迁移，我们在6只Wistar雄性大鼠（7周龄、5和10 g /kg体重）颈静脉注射了黄绿色荧光阳离子聚苯乙烯纳米粒子psnp (F-NP)，并使用光谱成像模式的LSM 710共聚焦显微镜检测其在AP中的存在。我们对AP的分析证实了F-NPs在该区域的存在。我们之前的研究结果表明，两个月的NPs暴露会影响心率和渗透调节，并增加后脑区（AP）小胶质细胞的反应性，AP是一个无血脑屏障（BBB）的心血管中心。今年，我们重点研究了孤立束核（NTS）的小胶质细胞反应性，这是一个与AP直接相邻并受BBB保护的区域。NTS是参与监测和调节血压水平的关键中心区域。结果显示，NPs组小胶质细胞在NTS中的反应性比AP组更强，表明循环NPs对NTS小胶质细胞的影响比对AP小胶质细胞的影响更严重。

This study investigates whether long-term oral exposure to nanoplastic alters cellular and molecular characteristics in blood-brain-free areas of the brain and their physiological functions. Five weeks-old male Wistar rats (n=6 per group) were fed daily with positively or negatively charged polystyrene nanoparticles (NPs) (50 nm diameter, 12.5 mg/kg body weight) for two months. To confirm the migration of circulating NPs to AP, we injected yellow-green fluorescent cationic polystyrene nanoparticles PSNPs (F-NP) in the jugular vein of six Wistar male rats (7 weeks old, 5 and 10 gr/kg body weight) and use confocal microscopy LSM 710 with spectral imaging mode to detect their presence in AP. Our analysis of the AP confirmed the presence of F-NPs in this area.Our previous findings indicate that a two-month NPs exposure affects heart rate and osmoregulation and increases the reactivity of microglial cells in the area postrema (AP), a blood-brain barrier (BBB)-free cardiovascular center. This year, we focused on the microglia reactivity in the Nucleus Tractus Solitarius (NTS), an area directly adjacent to the AP and protected by a BBB. NTS is a pivotal central area involved in the monitoring and regulation of blood pressure levels. The results revealed that the reactivity of microglia in NPs groups was more robust in the NTS than in the AP, indicating that the impact of circulating NPs is more severe on NTS microglia than on AP microglia.