Effects Of LED Phototherapy On Oxidative Damage And The MRNA Expression Of Specific DNA Repair Genes In Hyperbilirubinemia Neonates

Objective:To evaluate the extent of oxidative damage,antioxidant capacity,and the m RNA expression of specific DNA repair genes in hyperbilirubinemic neonates with the treatment of phototherapy.Methods:38 neonates(?35 weeks)with hyperbilirubinemia reaching phototherapy level were enrolled.Neonates were classified into two groups:19 received light-emitting diode(LED)phototherapy,19 received intensive LED phototherapy.Blood sample were collected before phototherapy and 12 h after phototherapy to separate plasma and peripheral blood mononuclear cell(PBMC).8-hydroxy-2-deoxyguanosine(8-OHd G)concentration,Malondialdehyde(MDA)level,superoxide dismutase(SOD)activity,glutathione peroxidase(GSH-Px)activity and the m RNA expression of P53,human 8-oxoguanine DNA glycosylase(h OGG1),human Mut T homolog1(h MTH1),human Mut Y homolog(h MYH)genes were measured before and after phototherapy.Results:The total bilirubin(TB)level significantly decreased after phototherapy in both groups(P<0.001 for both).The 8-OHd G concentration significantly increased after phototherapy in both two groups(P<0.05 for both).GSH-Px activity was significantly decreased after phototherapy in both groups(P < 0.05 for both).The MDA level was significantly increased after phototherapy in the intensive LED phototherapy group(P<0.001).And the SOD activity was significantly lower after phototherapy than before phototherapy in the intensive LED group(P<0.001).However,there was no significant difference in MDA level and SOD activity between prephototherapy and postphototherapy in LED group.No significant difference was observed in P53 m RNA expression after phototherapy compared to the level before phototherapy.The m RNA expression of h MTH1 and h OGG1 was significantly increased after phototherapy in the LED group(P<0.05),but there was no significant difference in intensive LED group.The h MYH m RNA expression significantly decreased after phototherapy in the intensive LED group(P < 0.05).However,there was no significant difference in h MYH m RNA expression between prephototherapy and postphototherapy in LED group.Positive correlation was observed between P53 and h OGG1,P53 and h MTH1,P53 and h MYH,h OGG1 and h MTH1,h OGG1 and h MYH,h MTH1 and h MYH m RNA m RNA expression before and after phototherapy in two groups.Conclusion:1.LED phototherapy with different intensity may induce oxidative damage,including DNA damage.2.LED phototherapy with different intensity may reduce the antioxidant enzyme activity.3.The lower intensity LED phototherapy may up-regulate the m RNA expression of repair genes to repair oxidative DNA damage when oxidative stress occurs.