An in vitro Study of the Effect of Bacterial Lipopolysaccharide on Transcription Levels of SLC Family Transporter Genes in Microglia

Neurodegenerative diseases are accompanied by neuroinflammation and excitotoxicity, in which microglia and astrocytes play an important role. However, there is still no clear understanding of how glial cells interact in the processes associated with inflammatory reactions in the brain. The study was aimed to elucidate the in vitro effect of bacterial lipopolysaccharide (LPS), as an inducer of inflammatory reactions, on transcription levels of the Slc superfamily transporter genes in microglia, depending on the astrocytic environment, as well as to reveal regional differences in these levels. The study was carried out on microglial cells in both monoculture and co-culture with astrocytes. Microglia and astrocytes were isolated from the cortex and hippocampus of 21-day-old Wistar rats. Microglial activation was induced by LPS. Transcription levels of the genes encoding Slc family transporters were analyzed by reverse transcription polymerase chain reaction (RT-PCR). LPS was shown to induce an increase in transcription levels of genes encoding the neuronal excitatory amino acid transporter 3 ( Slc1a1 , EAAT3), excitatory amino acid transporter 4 ( Slc1a6 , EAAT4), vesicular glutamate transporter 1 ( Slc17a7 , VGLUT1), and monocarboxylate transporter 1 ( Slc16a1 , MCT1a1) in microglial cells in vitro both in monoculture and in the presence of astrocytes. Transcription levels of the Slc family transporter genes significantly increased in all studied cultures compared to non-activated microglial cultures (control): in non-activated microglia-astrocyte co-cultures by 30.8–172.3%, in LPS-activated microglial monocultures by 33.5–63.3%, in LPS-activated microglia-astrocyte co-cultures by 17.8–76.0%. Moreover, regional differences were revealed in transcription levels of the above transporter genes in response to LPS administration. Thus, the data obtained confirm a change in the transcription profile of glutamate and monocarboxylate transporters upon LPS-induced activation of microglia, as well as the involvement of the astrocytic environment in these changes. Overall, it was shown that the exposure to a proinflammatory factor (LPS) activates the transcription of Slc family transporter genes in microglial cells.