Macrophage-Activated Products of Lacticaseibacillus paracasei N1115 Promote the Development of Primary Hippocampal Neurons

To make a preliminary investigation of the effect of the immune pathway mediated by live N1115 on the development of primary hippocampal neurons cultured . Live N1115 suspension of an appropriate concentration was used as the experimental group. Peptidoglycan (PGN) and lipopolysaccharide (LPS) were used as positive controls, and RPMI1640 medium served as the blank control. These were co-cultured with RAW264.7 cells to obtain the co-culture mediums and the total cellular RNA, and to measure the expression and secretion of cytokines. After centrifugation, the supernatants were co-cultured with primary hippocampal neurons at appropriate ratios. The co-culture mediums were collected, and the total cellular RNA was extracted to measure the expression of genes related to synaptic development in neurons. Following immunofluorescence staining of the primary hippocampal neurons, the presynaptic and presynaptic membrane-associated proteins, including synaptophysin (SYP) and the postsynaptic density protein 95 (PSD95),