Abstract
Purpose:
Microglia are resident macrophages of the central nervous system, including the neural retina. Microglia are critically involved in various retinal inflammatory and degenerative diseases. Recent studies have highlighted the importance of metabolic control of inflammation. The aim of this study was to characterize the expression of glucose transporters (GLUTs) in microglial cells under normal and inflammatory conditions.
Methods:
Primary microglial cells were cultured from 4-6 weeks C57BC/6J mice, and the phenotype was confirmed by confocal microscopic investigation of the expression of Iba-1, CD11b and F4/80. The expression levels of different types of GLUTS in microglial cells treated with normal glucose(5mM), high glucose (25 mM glucose), lipopolysaccharide (LPS,100ng/ml) and interleukin 4 (IL-4, 20 ng/ml) were evaluated by real-time RT-PCR and Western blot.
Results:
Under normal culture conditions, microglial cells express a variety of GLUTs including GLUT1, GLUTs3-6, and GLUTs8-13. The relative expression levels of GLUT mRNA were GLUT1 > GLUT8 > GLUT9 > GLUT5, GLUT6 > GLUT3, GLUT4. Western blot analysis showed that GLUT5 expression was significantly higher than other GLUTs. Surprisingly, high glucose, LPS or IL-4 treatment showed only mild effect in GLUT5 expression (~2-fold change in mRNA expression).
Conclusions:
Microglial cells express a variety of GLUTs. At the mRNA level, Glut1 shows the highest expression, whereas at the protein level, GLUT5 expression is higher than others. The mRNA expression levels of various GLUTs are relatively stable, and do not appear to be related to the activation state of microglial cells.