Bila I. The effect of agmatine on the ability of leukocytes to aggregate and migrate under experimental diabetes mellitus

The dissertation is devoted to the study of the effect of agmatine on the aggregation and migration abilities of peripheral blood leukocytes both in control rats and those with experimental diabetes mellitus (EDM) by determining changes in oxidative stress indices and polymerization-depolymerization processes of actin filaments. The administration of agmatine prevents the development of oxidative stress in rat leukocytes under streptozotocin-induced diabetes, suppresses the formation of active forms of oxygen, reduces the intensity of lipid peroxidation processes and the content of advanced oxidation protein products in plasma, and also increases the activity of the antioxidant system key enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase). After the injection of agmatine to both healthy and diabetic animals the enhancement of aggregation properties of peripheral blood leukocytes as were observed, which may be explained by the direct action of agmatine either on the state of surface glycoconjugates of leukocyte membrane or on the activity of enzymes which form the structure of carbohydrate determinants of adhesive molecules of these cells. The directed action of agmatine was also kept under the conditions of EDM. Thus it may be assumed that the administration of agmatine to animals with diabetes causes an increase in the affinity of WGA lectin binding to its complementary ligands due to an increase in the number of sialoglicoconjugates and residues of N-acetyl-D-glucosamine in the surface glycans of leukocytes. The initial level of polymerized actin in rat peripheral blood leukocytes of all the four groups was estimated by the level of fluorescence of phalloidine, which binds F-actin in the ratio of 1: 1 without binding G-actin. The digitized results of the signal intensity of fluorescence microscopy were expressed in conditional units. It was found that the level of F-actin in leukocytes under EDМ was significantly higher compared to the control, which indicates their pre-activated condition, the violation of depolymerization processes, changes in structural and functional properties of the cells thus decreasing their migration capacity under diabetes mellitus. After the injection of agmatine to both the control group of rats and under conditions of streptotrozotocin-induced diabetes, a decrease in the level of polymerized actin was observed. Such results in animals with EDМ following the injection of the studied polyamine may be attributed to the "removal" of the pre-activation state of cells, the intensification of actin polymerization-depolymerization, which was recorded as an increase in the long actin filaments content, thus increasing the migration capacity of cells. In leukocytes of animals with EDМ against a background of agmatine injection, the transduction of the lectin-induced signal via sialoglicoconjugates and the dynamics of quantitative redistribution of the content of actin fractions indicates that this polyamine helps restore and maintain the functional response of leukocytes to activation signals. Agmatine prevents the development of oxidative-nitrative stress in rat leukocytes in conditions of streptotrozine-induced diabetes by inhibition NO synthase, decreasing NO overproduction in leukocytes, reducing the intensity of lipid peroxidation processes, and also increasing the activity of key enzymes of antioxidant defense. Agmatin exerts hypoglycemic and antioxidant effects maintaining oxygen and nitrogen active forms concentrations within the limits of the physiological norm. This contributes to the restoration of the balance between the processes of polymerization and depolymerization of actin in blood leukocytes. The investigation of mechanisms underlying agmatine's influence on the aggregation and migration abilities of blood leukocytes under diabetes mellitus is a high pressing priority since the obtained results may contribute to the development of new approaches to the development of drugs with hypoglycemic, antioxidant and immunomodulatory effects.