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

这项研究调查了长期口服纳米塑料是否会改变大脑无血脑区的细胞和分子特征及其生理功能。五周龄的雄性Wistar大鼠（每组n=6）每天用带正电荷或带负电荷的聚苯乙烯纳米颗粒（NP）（50 nm直径，12.5 mg/kg体重）喂养两个月。为了确认循环NP向AP的迁移，我们在六只Wistar雄性大鼠（7周龄，5和10 gr/kg体重）的颈静脉中注射黄绿色荧光阳离子聚苯乙烯纳米颗粒PSNP（F-NP），并使用具有光谱成像模式的共聚焦显微镜LSM 710来检测它们在AP中的存在。我们对AP的分析证实了F-NPs在这一区域的存在。我们先前的研究结果表明，两个月的NPs暴露会影响心率和心率调节，并增加最后区（AP）中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，我们专注于孤束核（NTS）中的小胶质细胞反应性，该区域直接邻近AP并受到BBB的保护。NTS是参与血压水平监测和调节的关键中心区域。结果显示，NPs组中小胶质细胞的反应性在NTS中比在AP中更稳健，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.