Sinomenine inhibits Aβ-induced indirect toxicity to HT22 cells. A. An MTT reduction assay shows that conditioned medium from ADDL-treated BV2 cells reduces the viability of HT22 cells. However, the decrease in cell viability was ameliorated by sinomenine (n = 4 in all groups). B. TUNEL assay shows that sinomenine prevents indirect toxicity to HT22 cells. Sample images (B1) and quantified summary data (B2) of DAPI- or TUNEL-stained HT22 cells treated with different conditioned media show that conditioned medium from ADDL-treated BV2 cells significantly increased the number of TUNEL-stained cells. However, conditioned medium from ADDL + sinomenine-treated BV2 cells did not increase the number of TUNEL positive cells (n = 4 in all groups). Asterisks denote significant differences (p < 0.05). Scale bar, 100 μm.