Effect of nitric oxide synthase induction on the expression of mitochondrial respiratory chain enzyme subunits in mixed cortical and astroglial cell cultures

In the present study we evaluated the effects of NO synthase (NOS) inductio n on the regulation of cytochrome c oxidase (CO) and F0F1-ATPase subunit ex pression in astroglial and mixed cortical cell cultures. In mixed cortical cell cultures, 18 h of treatment with lipopolysaccharide (LPS, 0.1 mu g/mL) plus interferon-gamma (INF gamma, 10 U/mL) caused an increase of mRNAs for CO-I, F0F1-ATPase 6 and also for iNOS at 20 DIV. The induction of both CO- I and F0F1-ATPase 6 was abolished by the NOS inhibitor N-monomethyl-L-argin ine (NMMA) or by the enzymatic scavenger superoxide dismutase/catalase (SOD /CAT). In primary astroglial cell cultures, treatment for 18 h with increas ing concentrations of LPS and INF gamma, produced an increase in the amount of mitochondrial encoded CO-I and -II subunits, with no significant modifi cations of nuclear encoded subunit An increase was also observed at level o f transcription for CO-I and -II, and F0F1-ATPase 6 mRNAs. These effects we re abolished by addition of NMMA or SOD/CAT mRNA induction of CO-I was high er in mixed cortical than in astroglial cell cultures while that of F0F1-AT Pase 6 was similar in both cell types. These results suggest that the expre ssion of mitochondrial encoded subunits (CO-I, CO-II and F0F1-ATPase 6) is up-regulated in response to oxygen and NO reactive species. The activity of cytochrome c oxidase decreased after LPS/INF gamma treatment in both astro glial and mixed cortical cultures. The activity of ATP synthase was unmodif ied, while ATP content drastically decreased after LPS/INF gamma treatment, in both astroglial and mixed cortical cultures. The enzymatic activities o f catalase and Mn-SOD (mitochondrial) showed a significant increase after L PS/INF gamma treatment, which was abolished by MMMA. (C) Societe francaise de biochimie et biologie moleculaire / Elsevier, Paris.