Trimethylamine N-oxide Aggravates Neuro-inflammation via lncRNA Fendrr/miR-145-5p/PXN axis in Vascular Dementia Rats

Abstract Vascular dementia (VaD) is the second most common dementia in the world, and our previous investigation demonstrated that Trimethylamine-N-oxide (TMAO) exacerbates cognitive impairment and neuropathological alterations in VaD rats. Thus, this study is to evaluate the potential mechanism of TMAO in VaD. The rats using the bilateral common carotid artery (2VO) model were administered TMAO (120 mg/kg) for 8 consecutive weeks, 4 weeks preoperatively and 4 weeks postoperatively. High-throughput sequencing was conducted to investigate the effects of TMAO treatment on lncRNA expression in rat hippocampus and bioinformatics analysis was performed to identify potential downstream targets. Learning and spatial memory capacities were measured, as well as inflammatory factors. Nissl staining was used to observe neuronal injury in the CA1 area of the hippocampus. TMAO administration upregulated lncRNA Fendrr expression in the rat hippocampus, while the damaging effects of TMAO were counteracted after knockdown of Fendrr. Fendrr exhibits highly expressed in 2VO rats and sponged miR-145-5p, which targets PXN. Silencing of Fendrr or PXN, or promotion of miR-145-5p improved neurological function injury, reduced neuronal damage, as well as repressed inflammation response. Inhibition of miR-145-5p abrogated up Fendrr knockdown mediated influence on 2VO rats. To summarize, the results of this study indicated that TMAO inhibits the miR-145-5p/PXN axis by increasing the Fendrr expression, thus exacerbating the development of VaD.