THE EFFECT OF ACUTE HYPEGLYCEMIA ON THE ACTIVITY OF THE ANTIOXIDANT SYSTEM IN THE CENTRAL NERVOUS SYSTEM AND IN THE LIVER OF THE INVERTEBRATE MOLLUSK - LYMNAEA STAGNALIS

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Abstract


Comparison of dynamic changes of biochemical reactions in the liver and CNS of freshwater liver mollusc LYMNAEA STAGNALIS has been conducted. It has been conducted during incubation in the highly concentrated solution of glucose. The indicators of superoxiddismutase (SOD) activity, the level of renewed glutation (G-SH), Se-dependant glutation peroxidase (Se-GP) and TBA-active products were estimated and compared. Also for the tissues of the Central Neural System and tissues samples of liver it was found out by glucoseoxidate method the concentration of glucose in haemolymph of the investigated biological object in the conditions of hyperglycemia. A comparative estimation of the general protein concentration in both tissues was conducted. Resistance of the liver tissue to hyperglycemia and a reverse effect towards CNS was found out.

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Introduction. Interstitial glucose level is one of the most important physiological constants. Its fluctuations leads to various deviations including those related to the nervous functions [1]. Some of them also associated with the oxidative stress enlargement [2, 3]. Glucose is an endogenous component of mollusks’ internal environment, an active participant in carbohydrate metabolism, and its concentration in hemolymph can vary in a wide range of values [4]. The aim of research was to estimate the impact of acute, short-term hyperglycemia on the antioxidant defense in the brain and in the liver of fresh-water pond snail Lymnaea stagnalis, a model organism which is routinely used in various types of neurophysiologic research. Material and methods. Mollusks (Lymnaea stagnalis) were collected in shallow running waters in the autumn. In the laboratory animals were kept in aquariums, while each species had at least 1 liter of water. The room temperature was 20 ± 1 °С. The water was changed regularly. Lettuce (ad libitum) was as food. For the experiment animals were selected by approximately the same weight and size. The animals of the tested group were put to the aquariums containing glucose (100 mM, final). Control group was left in the aquariums with tap-water only. It was preliminary found that such a manipulation leads to about 10 times growth of the glucose level in haemolymph of mollusks (approximately from 0.1 to 1 mM or higher). After 2 h of incubation both groups were placed to the aquariums where they are usually kept. Lymnaea’s CNS (central ganglionic ring and buccal ganglia) was removed 24 h after the end of incubation and for further biochemical assay. Results and discussion. It was found that the acute short-term hyperglycemia results in a 1.7 times increase in the G-SH level in the CNS, 1.5 times increase in SOD activity in brain homogenates compared with the control group. There were no statistically significant changes in the activity of Se-GP and TBA active products. The concentration of total protein and glucose in the homogenates of the nervous tissue also did not differ for the considered groups of mollusks. When analyzing biochemical parameters in liver homogenates, a 1.3 times increase in the activity of TBA active products was discovered. However, statistically significant changes in the activity of Se-GP, SOD, the level of G-SH, and the amount of total protein were not detected. Experimental data were processed by conventional methods of biomedical statistics [5]. Conclusion. We assume that a sharp short-term increase in the glucose level in the internal environment is associated with the development of oxidative stress in the central nervous system. Taking into account the signaling role of reactive oxygen species (ROS), this may lead to modification of the neural functions and behavior of animals. At the same time, liver cells are resistant to this effect, which implies the presence of a stronger and more active antioxidant system, allowing them to act as the main regulator of carbohydrate metabolism in the body of invertebrates. Acknowledgments. This work supported by BRFFR grant B049-19.

About the authors

V N Shadenko

Department of Human and Animal Physiology, Belarusian State University


A V Sidorov

Department of Human and Animal Physiology, Belarusian State University


References

  1. Tups A., Benzler J., Sergi D., Ladyman S. R., Williams L. M. Central regulation of glucose homeostasis. Comp. Physiol. 2017;7:741-764. https://doi.org/10.1002/cphy.c160015.
  2. Sidorov AV, Maslova GT. State of antioxidative protection in central nervous ganglia of the mollusc Lymnaea stagnalis at modulation of activity of the NO-ergic system. J. Evol. Biochem. Physiol. 2008;44(5):435-441. https://doi.org/10.1134/S0022093008050010.
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  4. Veldhuijzen JP. Effects of different kinds of food, starvation and restart of feeding on the haemolymph-glucose of the pond snail Lymnaea stagnalis. Neth. J. Zool. 1974;25:89-102. https://doi.org/10.1163/002829675X00146.
  5. Glantz S. Primer of Biostatistics. NY: McGraw-Hill, Inc.; 1994.

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