The Functional State of Rat Liver after the Long-Term Influence of Lp-2102 Oligoether and 2-Methoxyethanol

This investigation was performed to study the functional state of rat liver with the help of biochemical methods on the 60th day of the oral intake of the common industrial chemical pollutants - oligoether called "Laprols" 2102 (polyhydroxypropylene glycol with the molecular weight of 2100) and the product of its hydrolytic degradation and transformation 2-methoxyethanol. These compounds are characterized by large volumes of synthesis, wide use in various sectors of the economy, appearance in environmental water sources and possible negative impact on public health. It was found that the 60-days of oral toxification of rats with Lp-2102 oligoether and 2-methoxyethanol in 1/10 and 1/100 of DL50 led to the increased intensity of lipid peroxidation in liver. This was proved by the accumulation (p <0.05) of its products – malonic dialdehyde and dienic conjugates in comparison with the control group. The statistically significant (p<0.05) decrease in the reduced form of glutathione compared to the control group and elevation of its oxidized form were found against the background of an increase in lipid peroxidation products. It was the most noticeable when the dose was 1/10 of DL50. The impairment of oxidant-antioxidant systems in the direction of the activation of the level of free radicals as a result of the prolonged effects of these substances causes damage to the hepatocyte membrane, as evidenced by changes in activity of liver enzymes. Lp-2102 oligoether and 2-methoxyethanol in doses of 1/10 and 1/100 of DL50 on the 60th day of the experiment caused the significant increase in activity of serum alanine and aspartate aminotransferases. It was also proved that 60-day toxification of rats with these substances was accompanied by a statistically significant (p <0.05) reduction of activity of indicatory enzymes - glucose-6-phosphatase and tryptophan-2,3-dioxygenase in the microsomal fraction of hepatocytes. It was found that on the 60th day of the action of Lp-2102 oligoether and 2-methoxyethanol led to the inhibition of metabolic activity of hepatocyte mitochondria, as evidenced by the significant (p <0.05) reduction in the rate of oxygen uptake in non-acceptor environment as well as in the presence of an acceptor ADP and an uncoupler 2,4-dinitrophenol. The long-term toxification of rats with Lp-2102 oligoether and 2-methoxyethanol caused the depletion of energy resources in mitochondria of hepatocytes due to the reduction of the activity of Mg2+-ATPase and Ca2+-ATPase, ATP and ADP contents against the background of the elevated AMP level. It was found that the prolonged intake of Lp-2102 oligoether and 2-methoxyethanol reduced (p <0.05) the energy potential of mitochondria of hepatocytes compared to the control group of animals, especially in case of 1/10 if DL50 (on average 50 and 40%, respectively). The results allow us to make a conclusion that the hepatotoxic action of Lp-2102 oligoether and 2-methoxyethanol after the prolonged administration of 1/10 and 1/100 of DL50 by rats is one of the pathogenetic mechanisms of their biological effects. The results should be taken into consideration for the hygienic regulation of the content of substances in water.