Differential Effects of Decimetric\nElectromagnetic Microwaves on Pyruvate Kinase Activity in the Rat\nBrain during Ontogenesis

Abstract

Abstract The effect of decimetric microwaves (DMW) on the activity of pyruvate kinase (PK), one of the energy supply enzymes, was investigated in the brain structures of 3-, 6-, and 24-month-old white outbred male rats. Experimental rats were exposed on a daily basis to 10 and 30 µW/cm 2 of DMW radiation for 20 min over a period of 10 days. It was established that PK activity in the cortical and subcortical brain structures, which differ in their oxygen supply, morphofunctional and phylogenetic characteristics, reacts differently to the effect of DMW: at 10 µW/cm 2 it increases while at 30 µW/cm 2 it decreases. In mitochondrial subcellular fractions of the brain structures, PK\xa0activity was lower at 10 µW/cm 2 than at 30 µW/cm 2 . In cytosolic subcellular fractions, no significant differences were revealed in PK activity at different intensities of DMW radiation, while these indicators, taken separately, were significantly different compared to the control ( p < 0.01; p \xa0< 0.001). There are two alternative assumptions to explain the obtained results. An increased PK activity in the brain structures studied may reflect a metabolic adaptation aimed at protecting the structural integrity and functional components of nerve cells from detrimental effects of DMW radiation. Conversely, energy deficiency due to a decline in PK activity, in turn, causes various negative secondary metabolic changes and a free-radical oxidation in nerve cells. Our data reveal that both at 10 and 30 µW/cm 2 of DMW radiation the endogenous signals in the rat brain spread from cortical to subcortical structures, but PK activity does not recover to the level of the control values. It is hypothesized that under the effect of DMW radiation, the cerebellum, orbital and sensorimotor cortices serve as donors while the limbic cortex and hypothalamus as acceptors in the system of signal transduction.