Luteolin inhibits microglial neurotoxicity on photoreceptors. Phase contrast micrographs showing morphological changes of 661W photoreceptor cultures treated with conditioned media from BV-2 cells (A-D) or primary brain microglia (E-H). The supernatant from control-stimulated (A, E), 50 μM luteolin-treated (B, F), 50 ng/ml LPS-treated (C, G), or 50 μM luteolin + 50 ng/ml LPS-treated cells (D, H) was added to 661W photoreceptor cells, respectively. The micrographs shown are from one representative experiment out of three independent experiments with the same tendencies. Scale bar, 50 μM. (I) Apoptosis-related caspase 3/7 activation in 661W photoreceptor cells incubated with conditioned media from control-stimulated, 50 μM luteolin-treated, 50 ng/ml LPS-treated, or 50 μM luteolin + 50 ng/ml LPS-treated BV-2 cells. Results are calculated from two independent experiments performed in triplicate measurements. ** p ≤ 0.01, * p ≤ 0.05 for LPS vs. control and luteolin + LPS vs. LPS, respectively.