The Effect of High Glucose on the Activity of Superoxide Dismutase in NIN6N8a Cells

Bae, Hak Yeon; Lee, Byoung Rai; Kho, Kwang Sam

Abstract

BACKGROUND: Reactive oxygen species play a role in the pathogenesis of diabetes mellitus. Hyperglycemia may cause increased production of free radicals, and peroxide formation was increased in high glucose solution. It has been demonstrated that active oxygen species induce antioxidant enzyme expression in some tissues and cells. This study was designed to investigate the effect of high glucose on the activity of superoxide dismutase(SOD) in mouse insulinoma(MIN6N8a) cells. METHODS: MIN6N8a cells were grown in RPMI1640 medium with l0% fetal bovine serum and NIH3T3 cells used as a control cells. The cells were cultured in 5.6 and 22.2 mM glucose cnntained medium. The activities of SOD, catalase and GPX were determined in crude cell extract after 7 days of culture. The levels of CuZn-SOD were also measured with ELISA using anti-CuZn-SOD antibody. RESULTS: In MIN6NSa cells, the catalase activity was very low compared with NIH3T3 cells, but there was no difference in activities of CuZn-SOD and GPX between MIN6N8a cells and NIH3T3 cells. The activity of CuZn-SOD was decreased, while Mn-SOD was increased in MIN6NSa cells cultured with high glucose(22.2 mM) medium compared with those of normoglucose(5.6 mM) medium. However, the level of CuZn-SOD in MIN6NSa cells, when measured with ELISA was high in cells of cultured with high glucose medium. The SOD activity was not effected in MIN6N8a cells cultured with insulin contained medium. CONCLUSION: These experimental result suggest that the CuZn-SOD activity was decreased in MIN6N8a cells cultured with high glucose contained medium and this effect may be resulted from the protein inactivation rather than decrement of protein level.