456 ISSN 0095-4527, Cytology and Genetics, 2020, Vol. 54, No. 5, pp. 456–464. © Allerton Press, Inc., 2020. Ukrainian Text © The Author(s), 2020, published in Tsitologiya i Genetika, 2020, Vol. 54, No. 5, pp. 97–113. Effect of Photomodulation Therapy on Development of Oxidative Stress in Blood Leukocytes of Rats with Streptozocin-Induced Diabetes Mellitus O. I. Karmash a, *, M. Ya. Liuta a , A. M. Korobov b , and N. O. Sybirna a a Department of Biology, Ivan Franko Lviv National University, Lviv, Ukraine b Laboratory of Quantum Biology and Quantum Medicine, Karazin Kharkiv National University, Kharkiv, Ukraine *e-mail: sashakarmash@gmail.com Received December 6, 2019; revised February 19, 2020; accepted September 18, 2020 Abstract—Oxidative stress is among the main causes of developing severe complications in diabetes mellitus (DM). Existing pharmaceuticals, although efficient in reducing the blood glucose level, infrequently demon- strate antioxidant properties. On the other hand, there are many reliable reports about a broad range of bio- logical activity exhibited by photobiomodulation therapy (PBMT). Its potential sugar-lowering and antioxi- dant action makes this type of therapy a promising option for the treatment of DM and its complications. The effect of PBMT on the state of the antioxidant defense system in blood leukocytes was investigated in rats with streprozocin-induced DM. This study has shown that the PBMT increased superoxide dismutase (SOD) activity in rats with DM and normalized the content of oxidative stress markers (thiobarbituric acid (TBA)-active products, oxidatively modified proteins, and protein glycation end products). Keywords: diabetes mellitus, photobiomodulation therapy, blood leukocytes, oxidative stress, antioxidant protection system DOI: 10.3103/S0095452720050114 INTRODUCTION Diabetes mellitus is a severe chronic disease and, at the same time, is one of the most widespread chronic pathological conditions. It is characterized by uncontrol- lable hyperglycemia, which emerges due to the shortage of insulin or insulin-resistance in the peripheral tissues of the body. A chronic blood glucose increase typical of DM causes a significant group of severe complications, such as nephropathy, cardiomyopathy, and retinopathy. But the main cause of diabetic complications is the con- comitant development of oxidative stress through over- production of reactive oxygen species (ROS) capable to ruin cells, especially their membrane structures [1]. Photobiomodulation therapy (PBMT) has been known for almost 50 years but has not been widely applied due to insufficient knowledge about the molecular and cellular mechanisms of its action. At the same time, PBMT is practiced as a component of physiotherapeutic treatment methods in many dis- eases and applied widely around the world. PBMT is based on different light sources (lasers and photodi- odes) and different spectra in visible and infrared ranges. Apart from this, there are many reports con- firming the presence of biological activity of PBMT. It has been shown that PBMT actively affects cell prolif- eration (fibroblasts and keratinocytes) and wound healing [2] and activates the adenosine triphosphate (ATP) production by mitochondria [3]. The key point in the question about the use of PBMT is not about whether (or not) light has biolog- ical effects but about how energy from a laser or a pho- todiode acts at the cell and body levels and what are the optimal light parameters to be adopted for the use of PBMT in the treatment process. The current DM treatment approaches include insu- lin therapy, administration of sugar-lowering pharma- ceuticals, diet, and physical activities. The pharmaceuti- cals, in turn, possess different mechanisms for reducing blood glucose concentration; however, only some of them demonstrate antioxidant properties. Our previ- ous studies [4] have shown that PBMT reduces glu- cose concentration and glycosylated hemoglobin con- tent in the blood of rats with experimental DM. Apart from this, there are data indicating that, due to the application of PBMT, the level of malonic dialdehyde in the irradiated tissues in acute surgical injuries is reduced in rats with DM [5], which can confirm the PBMT effect on the cellular antioxidant defense system. The aim of our study was to investigate the effect of PBMT on the state of the antioxidant defense system of blood leukocytes in rats under conditions of oxida- tive stress induced by diabetes.