Figure 1: Neuroprotection of Astragalus-containing serum on 6-hydroxydopamine-induced neurotoxicity. (a) Cells were cultured with 10% control serum. (b-e) Cells were cultured with 10% control serum, 2% Astragalus-containing serum + 8% control serum, 4% Astragalus-containing serum + 6% control serum, and 8% Astragalus-containing serum + 2% control serum, respectively, for 1 h and then cultured with 100 μM 6-hydroxydopamine for extra 24 h. Astragalus-containing serum promoted the cell growth with larger number and longer neurites. (f) PC12 cells were incubated with 10% control serum for 1 h and then cultured with 6-hydroxydopamine in various concentration for 24 h. When the concentration of 6-hydroxydopamine increased, the cell viability was decreased gradually. Thus, 100 μM 6-hydroxydopamine was selected to establish neurotoxic model. (g) The effects of Astragalus-containing serum and 6-hydroxydopamine on cell viability. (h) The cells were cultured with Dulbecco's modified Eagle's medium containing 2%, 4%, and 8% Astragalus-containing serum for 24 h. *P < 0.05 (g, vs. 10% control serum + 100 μM 6-hydroxydopamine group); **P < 0.01 (f and g, vs. 10% control serum group); ***P < 0.001 (f, vs. 10% control serum group). 2%, 4%, 8%, and 10% referred to the ultimate concentrations of different serums in culture medium. The scale bar = 100 μm (n = 3).