| 2, 3, 7, 8-Tetrachlorodibenzo-p-dioxin (TCDD), one of the most toxic substances in the environment, has been characterized in multiple models across many developmental milestones. This research sought to further examine the suite of effects stemming from developmental exposure to TCDD in the avian model; and more importantly to elucidate the ability and effectiveness of an alternative treatment, red light (670nm; 4J/cm2) therapy, to attenuate TCDD toxicity in the parts per trillion (ppt) range. Phototherapy is an antique technology with both modern and novel applications, and prior to these studies had not been tested extensively in a developmental model. Upon red light treatment of embryos exposed to 200 ppt TCDD, in comparison to 200 ppt exposure alone without red light, embryonic mortality decreased by nearly half. In addition, red light therapy resulted in shorter pipping and hatching times, indicative of improved preparedness to hatch, as well as increased hatchling body weight and size of hatchlings exposed to 200 ppt TCDD throughout development. To characterize the mechanisms underlying the ameliorative effects of red light therapy on TCDD toxicity, a suite of biochemical endpoints were analyzed to evaluate oxidative and energy stress in the brain and liver. In both liver and brain tissues of hatchlings, red light therapy restored the redox (oxidized:reduced) glutathione balance, which was severely altered after TCDD exposure alone. Additional markers such as ATP, or cellular energy, and antioxidant enzymes that complement glutathione cycling indicated that red light therapy does improve energy availability in avian embryos exposed to lethal levels of TCDD. It is clear that daily red light therapy, as described in these studies, can effectively attenuate developmental TCDD toxicity, and decrease oxidative and energy stress. To our knowledge, this is the first such finding of an alternative, and externally applied, treatment mitigating the deleterious effects of TCDD. |
