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Disruption of cerebral cholesterol homeostasis by PS-NPs: astrocytic endoplasmic reticulum stress
Summary
Researchers found that polystyrene nanoplastics disrupt cholesterol production in brain support cells called astrocytes, which in turn prevents neurons from forming the connections needed for brain function. By triggering stress responses and blocking key cholesterol-making pathways, nanoplastics ultimately inhibit synapse formation — raising concerns about their potential role in neurological disease.
Cholesterol plays a crucial role in regulating synaptic membrane fluidity and ion channels. Due to the blood-brain barrier, cholesterol in the brain is primarily self-synthesized by astrocytes. However, limited research has been conducted on the effects of polystyrene nanoplastic (PS-NPs) on intracranial cholesterol metabolic pathways. In this study, we exposed whole-brain organoids (WBOs) to PS-NPs and identified significant changes in endoplasmic reticulum stress and cholesterol biosynthesis pathways through whole-transcriptome sequencing. To investigate potential mechanisms of altered cholesterol pathways, we constructed a Transwell neuronal-astrocyte co-culture model. Results demonstrated that PS-NPs induced significant endoplasmic reticulum stress in astrocytes, specifically manifested by elevated levels of ATF4 and CHOP, along with increased autophagy indicated by the elevated LC3-II/I ratio. PS-NPs significantly inhibited the AKT/ACLY pathway of cholesterol biosynthesis, leading to marked reductions in acetyl-CoA and cholesterol within astrocytes (P < 0.05). In addition, PS-NPs led to a significant reduction of apolipoprotein APOE, which hindered cholesterol transport and ultimately inhibited synaptin (SYN) formation. In summary, PS-NPs induce endoplasmic reticulum stress and autophagy in astrocytes, impair cholesterol de novo synthesis and apolipoprotein-mediated transport, ultimately inhibiting neuronal synaptogenesis. Furthermore, specific inhibition of ERs restored cholesterol synthesis in astrocytes and neuronal synapses. This study demonstrates that PS-NPs produce neurotoxic effects by affecting cholesterol homeostasis in the brain.
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