Crystalline lens: redox changes in response to the action of non-ionizing electromagnetic radiation

Abstract

Electromagnetic radiation (EMR) in the microwave range, even at non-thermal intensity, causes significant biochemical and physiological changes in living organisms, which are supposed to be associated with its possible oxidative effect. This work is devoted to the study of the mechanism of realization of the EMR effect in the eye lens at the level of redox state elements, based on the fact that this organ is the most suitable model: it functions semi-autonomously and has a well-organized system of antioxidant protection. The transparency of the lens is maintained by preserving the redox balance, in which the homeostasis of thiol compounds of protein and non-protein nature plays an important role. Our experiments were performed on rats using 460 MHz EMR for exposure at non-thermal intensities (power flux density between 10 and 30 µW/cm2). It has been shown that chronic exposure to EMR for up to two weeks caused changes in the redox state of the lens, which manifested in changes in the level of lipid peroxidation processes and the content of thiols of various natures. The substructures of the lens (cortical and nuclear regions) reacted to EMR exposure in different ways. Depending on the EMR intensity, pro- and antioxidant characters were revealed in their reactions. The dynamics of the oxidative reaction of lens substructures were also different under high- and low-intensity exposure. The character of the kinetics of changes in the products of oxidative reactions (malondialdehyde and lipid hydroperoxides) and reducing agents (non-protein and protein SH groups) in the lens of the irradiated organism suggested the role of the enzymatic thiolation-dethiolation system to preserve the redox balance in the substructures of the lens. In addition, the results on changes (kinetics) in the content of various protein SH-groups, i.e., hidden inside the protein molecule and exposed on its surface, during EMR exposure, as well as the data available in the literature, allow us to put forward suggestions about the supramolecular mechanism of homeostasis regulation, in particular, thiol homeostasis regulation in such high-protein structures as the lens, which can be realized by aggregation-disaggregation of protein molecules (crystallins in the case of the lens). Our results can serve as a basis for developing a new non-invasive approach to cataract prevention using low-intensity microwave radiation.