Figure 4: Astragalus-containing serum inhibits the elevation of reactive oxygen species production. PC12 cells were incubated in Dulbecco’s modified Eagle’s medium containing 8% Astragalus-containing serum and 2% control serum for 1 h and then using 100 μM 6-hydroxydopamine to treat for additional 24 h. (a-c) Reactive oxygen species production was measured by 2',7'-dichlorofluorescin diacetate dye. (d) The changes of fluorescent intensity of the cultured cells were analyzed. 6-hydroxydopamine obviously elevated reactive oxygen species production, whereas Astragalus-containing serum reduced the accumulation of reactive oxygen species. **P < 0.01 (d, vs. 10% control serum group); ##P < 0.01 (d, vs. 10% control serum + 100 μM 6-hydroxydopamine group). The scale bar in a indicates 100 μm (n = 3).