Pryshchepa I. V., Nedzvetskii V. S., Znanetska O. М.

Oles Honchar Dnipropetrovsk National University


Keywords: diabetes, central nervous system, emotional activity, intermediate filaments, glial fibrillary acidic protein, hydrated C60, oxidative stress.

Diabetes is a disease characterized by hyperglycemia resulting from deficiency of insulin secretion, the effectiveness of the hormone, or the joint effects of these factors. Severe metabolic abnormalities that occur in diabetes is the basis for the development of complications in the nervous system. The complications are the leading cause of disability and mortality among patients with diabetes mellitus, and primary attention should be paid to diabetic neuropathy, nephropathy and retinopathy. Given this, there is a right question: why diabetics primarily affects the nervous tissue, kidney and retina? According to numerous studies, this is due to the peculiarities of intracellular glucose metabolism in these tissues. Under conditions of hyperglycemia, excess glucose enters all cells, but most of them are the mechanisms by which cells remove excess glucose by restoring intracellular homeostasis. The feature of retinal capillary endothelial cells, mezanhial cells of renal glomeruli, neurons and Schwann cells are that these mechanisms are not available here, so they cannot remove the excess glucose, which leads to a sharp increase in its concentration inside the cell . According to many researchers, that is the reason why these cells are affected first. This insight has led to an active search and development of tools that can not only effectively monitor the performance of blood glucose, but also reduce its concentration in the target cells.

Diabetes is often accompanied by impaired cognitive activity, cognitive deficits and increased risk of dementia, especially as for the elderly. It is known that in pathological conditions associated with neurodegenerative and age-related changes the generation of reactive oxygen and food increases, as nerve cells are extremely sensitive to oxidative stress. These observations confirm the idea that mnemonic dysfunction is largely associated with the disorder of glucose metabo­lism and the development of oxidative stress in the cells of the brain. The affection of the peripheral nervous system is also due to the complex metabolic and cardiovascular disorders. Metabolic disturbances in diabetes include many factors, among which the most important ones are the long-term chronic insufficiency of insulin and hyperglycemia. The increased level of blood glucose initiates a series of biochemical changes that are the leading factors in the development of pathological lesions in the patients with diabetes. In the pathogenesis of diabetic complications the leading role of oxidative stress is beyond any doubt. It has been found that hyperglycemia resulting from activation of some biochemical processes leads to the accumulation of free radicals. As it is known, a free radical is a molecule or its part that has an unpaired electron on the outer molecular or atomic orbit. The presence of such an electron gives to radical a very high oxidative ability. Increased formation of free radicals is realized as the oxidation of most hydrocarbons and carbohydrates in combination with protein in autooxidation fatty acids in triglycerides, phospholipids and cholesterol esters. The latter damage intracellular membrane proteins, nucleic acids and lipids, and cause the degradation and aging of cells. The accumulation of free radical oxidation products contributes to the development of pathological processes: dysfunction of mitochondria and changes in the synthesis of fatty acids and prostaglandins, membrane damage and endothelial dysfunction, hypercoahulation. Endothelial dysfunction plays an important role in the development of coronary heart disease, hypertension, arteriosclerosis, cerebral circulatory disorders in patients with diabetes.

Hyperhichemical state was induced by intraperitoneal injection of streptozotocin (STZ, 50 mg/kg). Experimental work was conducted on sexually mature (24–25 weeks) Wistar rats. The animals were divided into four groups, which consisted of 8 animals each. The first group – TSW, the second – STZ + C60HyFn, the third – C60HyFn, the fourth – saline.

The fractions of soluble, cytoskeleton and membrane proteins were obtained from the tissues of hippocampus, cortex and cerebellum 28 days after the induction of hyperglycemia and putting of C60HyFn. After decapitation the brain was removed, cooled and separated into sections. The content of soluble and filament forms of GFAP was determined using immunoblotting. Statistical analysis of the results was performed using SPSS 10,0 for Windows, the difference was considered significant at p <0,05.

The behavior testing of control, STZD and diabetic groups of animals that received injections of hydrated fullerene, was done using the test "open field". It has been determined that the inhibition of locomotor activity of the second group of animals is 1,2 and 1,4 times compared with the control and STZD + C60HyFn groups respectively.

In the group of STZD animal the rates of search activity (mink reflex) reduced to 1,15 times compared with the control one. The inhibition of search activity has been found in STZD group of animals that received injections C60HyFn (0,1 mg / kg body weight) 1,23 and 1,06 times compared with the second and control ones. The group of STZD animals has the lowest emotional activity index (poles). It is 1,2 times smaller relative to the control one. The same figure of STZD + C60HyFn group of animals is 1.01 and 1,23 times higher than the second and control groups of animals respectively.

The indicators of emotional activity (grooming) of the second group of animals were 1.25 and 1.3 times reduced compared with the control and STZD + C60HyFn groups of animals. In the group of diabetic animals that received injections of hydrated fullerene the indicators of emotional activity (grooming) increased to 1,03 and 1.29 times compared with the control and STZD groups of animals respectively.

One the grounds of the above parameters the change of behavioral responses it can be concluded that the introduction of C60 has largely restored the normal functioning of nervous system of animals.