644. CHRONIC MORPHINE EXPOSURE ALTERS THE MOLECULAR CARGO OF BRAIN-DERIVED EXTRACELLULAR VESICLES: UPREGULATION OF ARC AND NEUROPLASTICITY-RELATED PROTEINS

Abstract Background Brain-derived extracellular vesicles (BDEVs) are nanometer-sized particles involved in cellular communication that play important roles in maintaining brain function, including supporting synaptic transmission and promoting dendritic spine formation. Exposure to addictive drugs alters BDEVs cargo composition, potentially influencing drug-induced neuroadaptations. However, the effects of chronic opioid exposure on the mRNA and proteomic profiles of prefrontal cortex derived EVs remain unexplored. Aims & Objectives This study aims to characterize transcriptomic and proteomic alterations in the extracellular vesicles from the prefrontal cortex following chronic opioid exposure and assess their functional impact on neuronal gene expression. Method We employed a straightforward model by administering chronic morphine treatment to male rats and evaluated the alterations in the extracellular vesicle cargo isolated from their prefrontal cortex. Using transcriptomic and proteomic analyses, we characterized changes in BDEVs cargo. To assess functional implications, we treated primary neuronal cultures with BDEVs from morphine- and vehicle-treated rats and performed a transcriptional profile. Results RNA sequencing identified upregulation of the ARC gene, a key regulator of synaptic plasticity and extracellular vesicle formation. Proteomic analysis revealed 47 differentially expressed proteins out of 734 evaluated, many associated with pathways relevant to neurodevelopment and addiction. Notably, BDEVs from morphine-treated rats altered the expression of 17 genes in recipient neurons, including PSEN1, a gene implicated in neurodegeneration and ARC interaction. Discussion & Conclusions Together, our findings highlight a potential role of ARC in BDEV-mediated neuroplasticity and uncover novel molecular pathways linking opioid exposure to neurodegenerative processes.