Effect of serum in medium on the expression of inducible nitric oxide synthase and superoxide dismutases in cultured C6 glioma cells.

It has been documented that C6 glioma cells can be changed into normal glial cells when they were cultured in serum free medium. In the present study, the expressions of inducible nitric oxide synthase (iNOS) and superoxide dismutase (SOD) were investigated. The mRNA level of iNOS was markedly increased by lipopolysaccharide (LPS) in cultured rat brain astrocytes (RBA-1) but not in C6 glioma cells. However, increase of mRNA for iNOS by LPS can be obtained in C6 glioma cells when they were cultured in serum free medium. The mRNA level of magnesium-SOD (Mn-SOD) was increased by LPS in both cells while the expression of constituted SOD (Cu,Zn-SOD) was not stimulated by LPS. Western blotting analysis indicating the amount of protein showed a similar change. After serum deprivation, the protein of iNOS or Mn-SOD was increased by LPS in C6 glioma cells in a way similar as that in RBA-1 cells. These results suggest that serum free conditioned C6 glioma cells were adapted to astroglial cell-like properties which may express more iNOS and Mn-SOD mRNA in the presence of LPS.