Role of reactive glia in modulation of neuroand synaptogenesis in vitro

Introduction. Activation of glial cells by lipopolysaccharide leads to the release of proinflammatory cytokines and the development of neuroinflammation, which, in turn, affects the processes of neuro- and synaptogenesis. However, the specific mechanisms of neuroglial and astrocytemicroglial interactions in these processes remain the subject of discussion. Aim of the study. Our aim was to study the role of microglia in the acquisition of a reactive phenotype by astrocytes in vitro, and the effect of lipopolysaccharide and astrocyte-conditioned medium on the neuro- and synaptogenesis of hippocampal neurons in vitro by immunocytochemistry methods. Methods. The study was carried out on glial and neuronal cell cultures from rat hippocampus. Lipopolysaccharide was added to mixed glial culture and pure astrocyte culture at concentrations of 1 and 10 μg/ml for 6, 12 and 24 hours. The cells were then fixed, stained for astrocytic marker GFAP. Lipopolysaccharide at a concentration of 10 μg/ml at 6 and 12 hours, as well as an astrocyte-conditioned medium were added to the culture of hippocampal neurons which were later fixed and stained for the marker of cell proliferation Ki67, presynaptic (Syn1) andpostsynaptic (PSD95) proteins. Results. The number of GFAP increased in mixed glial cultures after 6 and 12 h of incubation with lipopolysaccharide; in astrocyte culture, GFAP on the contrary, decreased. The addition of lipopolysaccharide and astrocyte-conditioned medium to neurons led to a decrease in cell proliferation and an increase in the amount of postsynaptic protein PSD95, while the amount of Syn1 changed only in case when lipopolysaccharide was added directly to neurons. Conclusion. In our work it was determined that astrocytes acquire a characteristic reactive phenotype only in the presence of microglial cells in vitro, as evidenced by an increase in the amount of GFAP. Astrocytes incubated with lipopolysaccharide are capable of modulating neuronal proliferation and synaptogenesis processes in vitro.

hippocampus, neurogenesis, lipopolysaccharide, neuroinflammation