Qiang Niu

Long-term exposure to polystyrene nanoplastics (PS-NPs) causes neurotoxicity, but the underlying mechanisms remain unclear. We combined network toxicology, molecular docking, and in vivo experiments to investigate the role of MTOR-TFEB-regulated autophagy in PS-NP-induced neurotoxicity. Potential targets related to PS-NPs and neurodegenerative diseases were screened from public databases. Enrichment analysis indicated involvement of neurodegenerative and autophagy pathways. Protein–protein interaction and docking simulations prioritized MTOR as a candidate target. Sprague–Dawley rats were gavaged with PS-NPs (0.15 or 1.5 mg/kg) for 60 days. Morris water maze tests showed impaired spatial learning and memory. Western blotting of hippocampal tissues revealed increased p-MTOR/MTOR ratios, decreased total cytoplasmic and nuclear TFEB, reduced lysosomal proteins (LAMP2, CTSD, and CTSB), elevated autophagy markers SQSTM1 and MAP1LC3B-II, and altered apoptosis regulators (BAX up and BCL2 down). Collectively, PS-NPs disrupt the MTOR-TFEB axis, impair lysosomal function and autophagic clearance, and promote apoptosis, leading to neurocognitive deficits. These findings provide mechanistic insights into the MTOR-TFEB axis and highlight it as a candidate pathway warranting further evaluation as a potential intervention target.

Excessive fluoride exposure induces developmental neurotoxicity, but effective preventive strategies are currently scarce. Melatonin (Mel), a lipophilic hormone secreted by the pineal gland, exerts antioxidant, anti-inflammatory, and neuroprotective properties. This study aimed to explore Mel’s protective effect and mechanism against fluoride-induced developmental brain injury. We employed a network pharmacology approach to screen the common targets of Mel and fluoride-induced brain injury and performed enrichment analysis. A total of 189 common targets were identified, and these targets were mainly enriched in the HIF-1 signaling pathway and oxidative stress-related pathways. In vivo, Sprague Dawley rats were subjected to perinatal sodium fluoride (NaF) exposure with/without Mel; in vitro, HT22 cells were subjected to NaF and/or Mel. The results showed that Mel improved cognitive impairments and alleviated structural damage to hippocampal neurons and mitochondria. Furthermore, Mel upregulated SIRT3 and downregulated HIF-1α, thereby restoring mitochondrial oxidative phosphorylation and ATP content. This study demonstrates that Mel alleviates fluoride-induced developmental neurotoxicity by improving mitochondrial function through regulating the SIRT3/HIF-1α signaling pathway. This not only offers a novel perspective for elucidating the underlying molecular mechanisms of fluoride-induced developmental neurotoxicity but also provides a theoretical foundation for Mel as a potential protective candidate against fluoride exposure.