670 nanometer light treatment attenuates dioxin toxicity in the developing chick embryo

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is an acutely toxic anthropogenic chemical. Treatment with a red to near-infrared (630-1000 nm) light-emitting diode (LED) attenuates the toxicant-induced oxidative stress and energy deficit in neuronal cell culture. For this study, fertile chicken (Gallus gallus) eggs were injected once at the start of incubation with sunflower oil vehicle or 200 pg TCDD/g egg (200 parts per trillion), an environmentally relevant dose. Daily LED treatment after TCDD exposure reduced embryonic mortality by 47%. LED treatment of TCDD-exposed eggs also decreased the hepatic oxidized-to-reduced glutathione ratio by 88%. Activities of other hepatic indicators of oxidative stress, such as glutathione reductase and catalase, were increased after LED treatment of TCDD-exposed eggs. Our study demonstrates that 670 nm phototherapy can mitigate the oxidative stress and energy deficit resulting from developmental exposure to TCDD while reducing TCDD-induced embryo mortality. Moreover, LED treatment restores hepatic enzyme activities to control levels in TCDD-exposed embryos. The effective attenuation of TCDD-induced embryo toxicity by LED treatment could extend to mitigating the effects of other teratogens that induce oxidative and energy stress.