Mono(2-ethylhexyl) phthalate impairs synaptic structure via altering long non-coding RNA MALAT1 in primary...

Di-(2-ethylhexyl) phthalate (DEHP) is a typical environmental endocrine disruptor. Its main metabolite mono(2-ethylhexyl) phthalate (MEHP) is highly reactive and toxic that plays a major role in metabolizing. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is one of Long non-coding RNAs (lncRNAs) which has a significant part in regulating synapse formation and maintenance. In this study, the extracted primary hippocampal neurons were used as the research object, and the MEHP exposure model was established. The optical microscope, immunofluorescence experiment and immunocytochemistry experiment were used to take pictures to analyze the changes in dendritic length, dendritic spines and synaptic density. PCR experiments were used to detect the expression of lncRNA MALAT1, mRNA cAMP response element bind protein (CREB), Postsynaptic density 95 (PSD95), and Neuroligin1 (NLGN1). And, antisense oligonucleotide (ASO) and negative control (NC) transfection were used to established MALAT1 knock down model of primary hippocampal neurons to analyze changes in synaptic density and the underlying mechanisms. Results indicated that exposure to MEHP reduced dendritic length, the density of dendritic spines and synapses density of primary hippocampal neurons. It also altered lncRNA MALAT1 and reduced mRNA CREB, PSD95, NLGN1 expressions. After knocking down MALAT1, the damages of dendrites and synapses as well as the down-regulating of CREB/PSD95 caused by MEHP were restored in neurons. These results suggested that MEHP exposure could decrease the dendritic length, dendritic spine and synapse density of hippocampal neurons and impair hippocampal synapses, which might be attributed to down-regulated CREB/PSD95 induced by alterated lncRNA MALAT1.