Sinomenine inhibits Aβ-induced indirect toxicity to primary hippocampal cells. (A) Sample images of DAPI- or TUNEL-stained primary hippocampal cells treated with BV2-conditioned media as indicated. Scale bar, 100 μm. (B) Quantified summary data show that conditioned medium from ADDL-treated BV2 cells significantly increased the number of TUNEL-positive cells. However, the number of TUNEL-positive cells was not increased when the cells were treated with conditioned medium from ADDL plus sinomenine-treated BV2 cells (n = 3 in all groups). Asterisks denote significant differences (p < 0.05).