[The role of polypeptide compounds in mechanism of CNS plasticity in patients with hereditary pathology of peripheral motor neuron]

Synaptic pruning is a physiological mechanism of neuroplasticity, which is regulated through synthesis of growth polypeptides, neurotrophins. The role of neurotrophins in the mechanism of synaptic pruning in patients with hereditary pathology of peripheral motor neuron was studied in a clinical experimental trial. It was found that patients had elevated levels of regulatory growth polypeptides, which led to the axon growth inhibition effect in organotypic tissue cultures. Thus, neurotrophin overexpression can be considered as a factor preventing synaptic pruning and contributing to further process of neurological degeneration in nerve tissue in patients with hereditary pathology of peripheral motor neuron.

[INVOLVEMENT OF р38 МАРК OF SENSORY NEURONS IN OUABAIN-ACTIVATED SIGNALING CASCADE]

Recent investigations of the new transducting function of Na+,K+-АTPase is of great interest. Na+,K+-АTPase might be a target (receptor) for cardiotonic steroids. This membrane protein switches on intracellular signaling mechanisms due to its ligand-receptor interactions with the steroids that, in turn, result in activation of intracellular cascade processes. р38 belongs to mito-gen-activated protein kinase family (MAPK). The kinase transduces signals of wide range intra-cellular signaling cascades that control proliferation, differentiation, and survival. Using embryonic organotypic tissue culture method the present work shows that р38 МАРК is involved in the signal transducting process in series with Na+,K+-АTPase.

Modulation of the transducer function of Na+,K+-ATPase: new mechanism of heart remodeling

Endogenous digitalis-like factors were found in the mammalian and human blood. It was the starting point for the elucidation of the new non-pumping function of the Na⁺,K⁺-ATPase. It was previously well known that Na⁺,K⁺-ATPase is a pharmacological target receptor for cardiac glycosides (J.C. Skou. 1957. Biochim. Biophys. Acta, 23: 394-401). We have investigated the trophotropic effects of such agents as ouabain, epinephrine, norepinephrine, atenolol, and comenic acid using the organotypic tissue culture combined with the reconstruction of optical cross sections and confocal microscopy. It was shown that the growth zone of organotypic culture forms a multidimensional structure. Our results indicate that the cardiac glycoside ouabain applied in endogenous concentrations (10^-8, 10^-10 mol/L) can modulate transducer function of Na⁺,K⁺-ATPase and control the cell growth and proliferation. It was also shown that Src-kinase is involved in "endogenous" ouabain activated intracellular pathways as a series unit. Epinephrine (10^-9-10^-14 mol/L) and comenic acid (10^-6-10^-10 mol/L) were demonstrated to modulate the growth of 10- to 12-day-old chicken embryo cardiac tissue explants in a dose-dependent manner. Epinephrine and comenic acid regulate growth and proliferation of the cardiac tissue via receptor-mediated modulation Na⁺,K⁺-ATPase as a signal transducer. The trophotropic effects of the investigated agents specifically control the heart remodeling phenomenon.

[Remodeling of Cardiovascular System: Causes and Consequences]

Literature and our data suggest the regulatory action of a number of biologically active substances (catecholamines, cardiac glycosides, β-blockers, angiotensin-converting-enzyme inhibitor) on the growth and proliferation of heart cells. By using of organotypic tissue culture has proved that the basis of this regulation is the ability of test substances, receptor- or transducer-mediated signaling to modulate the function of Na⁺, K⁺-ATPase. There is a delay in the development of vascular smooth muscle in the late postnatal period in rats with the blockade of the sympathetic nervous system in the prenatal period. The relationship between vascular remodeling and contractile activity is described. It seems that one of the causes of high blood pressure is a remodeling of the cardiovascular system, which precedes the development of hypertension.

[THE USING OF THE METHOD OF RECONSTRUCTION OF OPTICAL CROSS SECTIONS FOR INVESTIGATION OF THE TROPHOTROPIC EFFECTS OF ADRENALINE AND ATENOLOL]

The trophotropic effects of epinephrine and atenolol were investigated by using the organotypic culture method combined with the method of the reconstruction of optical cross sections. For the best possible image contrast was experimentally established the correction for Petri dish bottom thickness equal to 1 mm (objective lens Carl Zeiss). It was shown by method of the reconstruction of optical cross sections that growth zone in organotypic culture forms a multidimensional structure. In the presence of atenolol (10(-4) M) the thickness of the growth zone of the cardiac tissue explants was above the reference value 212%. The thickness of the growth zone in the presence of epinephrine (10(-9)-10(-13) M) did not differ from the control values. Experimentally was proved that atenolol mimics the trophotropic effects of epinephrine and these effects of epinephrine is realized primarily through β1-adrenergic receptors.

The effect of marinobufagenin on the growth and proliferation of cells in the organotypic culture

In recent years, a substantial interest has been aroused in investigating Na(+),K(+) ATPase as a membrane structure which not only performs its direct function in maintaining the gradients of Na(+) and K(+) concentrations, but also may participate in the intracellular signal transduction processes in response to various physiological stimuli. The effect of marinobufagenin, a digitalislike factor, on the growth and proliferation of sensory ganglia, cardiac, retina, skin, and liver tissue explants of 10-12day old chicken embryos was investigated by the organotypic culture method in a wide range of concentrations (10(-10) to 10(-4) M). It was first demonstrated that marinobufagenin inhibited the growth of the investigated tissue explants in the dosedependent but not tissuespecific manner. The experimental data obtained allow us to suggest that the mechanism of regulation of tissue growth by marinobufagenin during the embryonic period of ontogenesis is associated with the modulation of the pump function of Na(+),K(+) ATPase but not its transducing function.

[The influence of ouabagenin on the growth and proliferation of cells in the organotypical culture]

The aim of the present work was to investigate the effect of ouabagenin on the growth and proliferation of cells in organotypic culture. The objects of study were explants of nerve, cardiac, retina and liver tissue of 10-12 day old chicken embryos. Inhibitor of Na+,K(+)-ATPase ouabagenin was investigated in a wide range of concentrations (0.1 nM-1 mM). It has been found that the ouabagenin controls cell growth and proliferation in a dose-dependent manner and tissue-unspecific. The data obtained show that ouabagenin regulates only the pumping function of Na+,K(+)-ATPase.

Modulation of signal-transducing function of neuronal membrane Na+,K+-ATPase by endogenous ouabain and low-power infrared radiation leads to pain relief

Effects of infrared (IR) radiation generated by a low-power Co2-laser on sensory neurons of chick embryos were investigated by organotypic culture method. Low-power IR radiation firstly results in marked neurite suppressing action, probably induced by activation of Na+,K+-ATPase signal-transducing function. A further increase in energy of radiation leads to stimulation of neurite growth. We suggest that this effect is triggered by activation of Na+,K+-ATPase pumping function. Involvement of Na+,K+-ATPase in the control of the transduction process was proved by results obtained after application of ouabain at very low concentrations. Physiological significance of low-power IR radiation and effects of ouabain at nanomolar level was investigated in behavioral experiments (formalin test). It is shown that inflammatory pain induced by injection of formalin is relieved both due to ouabain action and after IR irradiation.

Effect of anoceptin on detoxifying function of the liver

The absence of negative effects of anoceptin on the liver tissue and detoxifying function was proven experimentally in vitro and in vivo. It was proven for the first time that comenic acid (anoceptin active substance) in concentrations of 10(-4)-10(-12) does not modulate the growth of liver explants from 10-12-day chicken embryos. The effect of anoceptin on the detoxifying function of the liver was studied on Wistar rats under conditions of hexenal-induced sleep. The drug was injected into the caudal vein for 90 days in a daily dose of 5, 100, or 300 mg/kg. The duration of hexenal-induced sleep was evaluated before and on days 30 and 90 of the study. Anoceptin did not modify the duration of hexenal-induced sleep and the status and detoxifying function of the liver.

[Application of polyguanidine solution for fixation of biological and anatomical specimens]

A new method for fixation of biological material is described, and its effectiveness is compared to that one of formalin fixation. As an embalming agent, polyhexamethylenguanidine (PHMG) hydrochloride was used. Using the proposed method of fixation, the anatomical and histological preparations of human organs and of chick embryos at developmental 12 days, were produced. The anatomical preparations obtained show the appearance, similar to that of the recently removed organs. Histological preparations were free from significant distortions of the microscopic characteristics of the specimens, which are typical to the material fixed with formalin. The results of the study suggest the possibility of PHMG application in the morphological studies.

[Role of oubain in regulation of growth of different tissues]

Using the method of organotypical cell culture, experimental data was obtained supporting the hypothesis that chelate complex ouabain-Ca2+ modulates the transducer function of Na+, K+- ATPase. Quantum-chemical calculations helped to elucidate two principally distinct modes for chelation of Ca2+ ions by ouabain molecule. It is predicted that ligang-receptor complex of ouabain-Ca2+--Na+,K+-ATPase is formed due to ion-ionic bonds. The forming of this complex switches on the transducer function of the sodium pump. Our data also show that removal of free Ca2+ ions from the cell culture media using EGTA has no effect on binding of ouabain with pumping control site of Na+K+-ATPase.