Effects of low-level light therapy on 2,3,7,8-tetrachlorodibenzo-p-dioxin and diabetes-induced oxidative damage in chicken and rat kidney

The objective of this study is to investigate the hypothesis that low-level light therapy (LLLT) with 670 nm light attenuates oxidative and bioenergetic stress and resulting renal damage induced by 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) and diabetes in chicken and rat kidney.;TCDD induces a wide range of adverse health effects in living organisms at least in part by inducing oxidative stress which provokes cellular injuries such as DNA and protein damage, lipid peroxidation, and cell death. TCDD-induced oxidative stress adversely affects developing kidneys and is implicated in progressive renal diseases and disorders such as necrosis in tubular cells, nephron hypertrophy and hyperplasia, and inflammatory nephritides. In addition, oxidative stress induced by diabetes contributes to the rate of progression and severity of diabetic complications, including diabetic nephropathy. The levels of reactive oxygen species (ROS) are under tight control by the protective actions of antioxidant defense systems in normal and healthy cells, but in diabetes and after TCDD exposure excessive cellular levels of ROS (oxidative stress) cause oxidative renal cell damage.;LLLT using light emitting diodes (LEDs) in the red to near infrared range has been employed in the treatment of soft tissue injuries and shown to promote tissue regeneration by increasing biological effects in cells. In the action spectra (630-1000 nm), the therapeutic effects of light treatment are mainly associated with the activation of cytochrome c oxidase, a primary photoacceptor molecule in the mitochondrial respiratory chain. The biological effects of LLLT vary according to wavelength, duration of light exposure, light intensity delivered, and energy density (dose or fluence). Among the wavelengths tested, the band in the range of 630-680 nm (peak at 670 nm) has been found to be optimal for light treatment by elevating the activity of cytochrome c oxidase.;The biochemical indicators of oxidative and energy stress in the chicken kidney exposed to TCDD (TCDD/LLLT study) were reversed by daily light therapy, restoring ATP and glutathione contents and increasing antioxidant enzyme activities to control levels. LLLT also normalized the level of lipid peroxidation increased by TCDD exposure. The results of this study demonstrated that LLLT could be useful as a non-invasive treatment for renal injury resulting from chemically induced cellular oxidative and energy stress. The study on the effects on a streptozotocin-induced rat model of chronic diabetes (Diabetes/LLLT study) was performed to clarify the hypothesis derived from the TCDD/LLLT study. The antioxidant effects of light treatment on diabetes-mediated kidney injury were also investigated biochemically to determine the potential of light treatment to negate the pathology caused by diabetes. Oxidative and energy stress were not induced in diabetic rats as clearly as in TCDD-exposed chickens, but daily phototherapy attenuated loss of renal function and antioxidant defense capabilities in diabetic animals, increasing the activity and expression of cytochrome c oxidase and catalase and the activity of Na K-ATPase. Levels of blood urea nitrogen reduced significantly in the diabetic rats were normalized to control levels by light therapy. LLLT also decreased the formation of DNA adduct (8-hydroxy-2'-deoxyguanosine, 8-OHdG).;Due to elevation of renal function and antioxidant defense systems by LLLT, LLLT is an appealing effective, non-invasive, and inexpensive therapy that could delay the development of progressive renal injury. The present study demonstrates that LLLT with 670nm light augments mitochondrial energy production and stimulates antioxidant protective pathways in injured renal cells. This non-invasive treatment may be of benefit in alleviating diabetes and other diseases that produce oxidative tissue damage and disrupt mitochondrial energy metabolism.