Apoptotic photoreceptor cell death induced by quinolone phototoxicity in mice

We examined retinal degeneration induced by phototoxicity of quinolone anti bacterial agents. Albino Balb/c and pigmented DBA/2 mice fasted overnight w ere given a single oral administration of ciprofloxacin (CPFX), levofloxaci n (LVFX), enoxacin (ENX), lomefloxacin (LFLX) or sparfloxacin (SPFX), follo wed by ultraviolet-a (UVA) irradiation at 1.5 mW/cm(2) for 4 h (21.6 J/cm(2 )). At 24 h after quinolone administration, the mice were sacrificed, and t he eyes were then histologically examined. ENX or LFLX at 200 or 400 mg/kg or SPFX at 50 or 100 mg/kg plus UVA induced retinal degeneration in Balb/c mice, whereas no histological change was observed in the eyes of DBA/2 mice . CPFX and LVFX at 800 mg/kg plus UVA had no effect on the eyes in either B alb/c or DBA/2 mice. Agarose gel electrophoresis showed that chromosomal DN A extracted from the eyes of Balb/c mice was fragmented in the SPFX 100 mg/ kg group, but not in the LVFX 800 mg/kg group. Tn the electron microscopic examination, swelling of mitochondria and disruption of the cytoplasm were observed in the photoreceptor inner segment (PIS) at 2 h, and disarrangemen t of lamellar disks in the outer segment (POS) and condensed chromatin in p hotoreceptor cell nuclei in the outer nuclear layer (ONL) were observed at 4 h after 100 mg/kg SPFX administration to Balb/c mice. These results sugge st that quinolone plus UVA irradiation induces retinal degeneration in albi no Balb/c mice, but not in DBA/2 mice, and this degeneration is associated with apoptotic photoreceptor cell death. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.