BACKGROUND: Phototherapy (PT) is the standard treatment of neonatal unconjugated hyperbilirubinemia. Fluorescent tube (FT)-emitted PT light is known to induce oxidative DNA damage in neonates. Nowadays, however, FTs have largely been replaced by light-emitting diodes (LEDs) for delivering PT. Until now, it is unknown whether LED-PT causes oxidative DNA damage. We aim to determine whether LED-PT induces oxidative DNA damage in hyperbilirubinemic rats.
METHODS: Adult Gunn rats, with genetically unconjugated hyperbilirubinemia, received LED-PT in the clinically relevant doses of 10 or 30 mu W/cm(2)/nm. Urine was collected at 0, 24, and 48 h of PT. A group of young Gunn rats received intensive LED-PT of 100 mu W/cm(2)/nm for 24 h. Urine was collected every 8 h and analyzed for the levels of oxidative DNA damage marker 8-hydroxy-2'deoxyguanosine (8-OHdG) and creatinine. DNA damage was evaluated by immunohistochemistry (gamma H2AX) of skin and spleen samples.
RESULTS: LED-PT of 10 and 30 mu W/cm(2)/nm did not affect urinary concentrations of 8-OHdG and creatinine or the 8-OHdG/creatinine ratio. Likewise, intensive LED-PT did not affect the 8-OHdG/creatinine ratio or the number of gamma H2AX-positive cells in the skin or spleen.
CONCLUSIONS: Our results show that LED-PT does not induce oxidative DNA damage in hyperbilirubinemic Gunn rats either at clinically relevant or intensive dosages.