Brilliant Blue G protects against photoreceptor injury in a murine endotoxin-induced uveitis model

We previously reported that P2X7 receptor antagonists prevented the retinal injury caused by N-methyl-n-aspartic acid. It has been reported that activation of P2X7 receptor is involved in the secretion of proinflammatory cytokines by macrophages, monocytes, and microglia. Although retinal inflammation is known to cause photoreceptor cell death, it is unclear whether a noncompetitive antagonist of P2X7 receptor can protect photoreceptor cells against inflammation-induced injury. We examined whether Brilliant Blue G (BBG), a potent noncompetitive antagonist of P2X7 receptor, had neuroprotective effects on photoreceptor cell injury in a murine endotoxin-induced uveitis (EIU) model. EIU was evoked by lipopolysaccharides (LPS; 10 mg/kg/day) administered intraperitoneally once a day for 4 days. BBG (50 mg/kg/day) and indomethacin (10 mg/kg) were also injected intraperitoneally just before LPS injection. BBG significantly prevented photoreceptor cell loss and reduction of the amplitudes of dark-adapted and light-adapted flush electroretinograms induced by LPS, whereas indomethacin did not show such protective effects. These results indicated that BBG is protective against photoreceptor cell injury in EIU in the mice in vivo, suggesting that P2X7 receptor antagonists may be good candidates for preventing photoreceptor degeneration induced by inflammation.