I. Yu. Malyshev

The function of endogenous protective systems in patients with insulin-dependent diabetes mellitus and polyneuropathy: Effect of antioxidant therapy

Abstractα-Lipoic acid is a very efficient antioxidants for the treatment and prevention of diabetic neuropathy. The aim of the present study was to evaluate the function of nitric oxide (NO) and stress proteins (HSP72) in insulin-dependent diabetes complicated by polyneuropathy and possible contribution of these systems to the therapeutic effects of α-lipoic acid. Plasma content of nitrites and nitrates in diabetic patients was almost 2-fold below the normal. The treatment with α-lipoic acid completely normalized the plasma content of these stable NO metabolites. The majority of patients had also low level of HSP72. Positive clinical effects of α-lipoic acid were accompanied by normalization of HSP72 synthesis. Thus, activation of the NO and HSP protective systems is involved in the therapeutic effect of α-lipoic acid in diabetic patients (type 1 diabetes mellitus) with polyneuropathy.

Prevention of neurodegenerative damage to the brain in rats in experimental Alzheimer's disease by adaptation to hypoxia

We report here studies addressing the possibility of preventing neurodegenerative changes in the brain using adaptation to periodic hypoxia in rats with experimental Alzheimer’s disease induced by administration of the neurotoxic peptide fragment of β-amyloid (Ab) into the basal magnocellular nucleus. Adaptation to periodic hypoxia was performed in a barochamber (4000 m, 4 h per day, 14 days). The following results were obtained 15 days after administration of Ab. 1. Adaptation to periodic hypoxia significantly blocked Ab-induced memory degradation in rats, as assessed by testing a conditioned passive avoidance reflex. 2. Adaptation to periodic hypoxia significantly restricted increases in oxidative stress, measured spectrophotometrically in the hippocampus in terms of the content of thiobarbituric acid-reactive secondary lipid peroxidation products. 3. Adaptation to periodic hypoxia completely prevented the overproduction of NO in the brains of rats with experimental Alzheimer’s disease, as measured in terms of increases in tissue levels of stable NO metabolites, i.e., nitrites and nitrates. 4. The cerebral cortex of rats given Ab injections after adaptation to periodic hypoxia did not contain neurons with pathomorphological changes or dead neurons (Nissl staining), which were typical in animals with experimental Alzheimer’s disease. Thus, adaptation to periodic hypoxia effectively prevented oxidative and nitrosative stress, protecting against neurodegenerative changes and protecting cognitive functions in experimental Alzheimer’s disease.

Detection and Description of Various Stores of Nitric Oxide Store in Vascular Wall

We analyzed the possibility of the existence of various NO pools in the vascular wall. Incubation of isolated rat aorta with dinitrosyl iron complex (NO donor) led to the formation of NO stores in the vascular wall detected by vascular relaxation response induced by diethyldithiocarbamate and N-acetylcysteine. Comparison of the effects of successive application of diethyldithiocarbamate and N-acetylcysteine revealed two NO pools (one pool responded to both agents, while other responded only to N-acetylcysteine). Inhibition of guanylate cyclase with methylene blue abolished the response to diethyldithiocarbamate, while the reaction to N-acetylcysteine decreased by the value, corresponding to diethyldithiocarbamate-dependent relaxation. It is hypothesized that in the vascular wall NO is stored in the form protein-bound dinitrosyl iron complexes and S-nitrosothiols in hydrophilic and hydrophobic cell compartments.

HYPOTENSIVE EFFECT AND TISSUE DISTRIBUTION OF THE DINITROSYL IRON COMPLEXES, A NITRIC OXIDE DONOR

Hypotensive effect of the dinitrosyl iron complexes, an NO donor, is compared with distribution of these complexes in organs and tissues after their intravenous administration to wakeful animals. Hypotensive effect of iron complexes depended on dose and postinjection time. There was a strong correlation between hypotensive effect and the content of dinitrosyl iron complex in the studied organs. Effective dose of dinitrosyl iron complexes that did not provoke adverse effects was about 200 mg/kg. This preparation is a prospective source of NO to treat and prevent pathological states related to NO deficiency.

Nitric Oxide Storage in the Cardiovascular System

Nitric oxide (NO) is a highly reactive substance with short lifetime. In conditions of a living organism NO can be bound by the complexes used for transport and intracellular storage of NO. The main biological forms of NO store include S-nitrosothiols and dinitrosyl iron complexes capable of interconversion. The NO store formed by these complexes in the vascular wall, on the one hand, provides for protection from excessive free NO after its overproduction and, on the other hand, can be an additional NO source when it is deficient. Apparently, the efficiency of NO storage is genetically determined and corresponds to the inherited level of NO production in the organism. Controlled modulation of formation and dissociation of the NO store is a promising trend for further investigation.

Role of heat shock proteins HSP70 and HSP32 in the protective effect of adaptation of cultured HT22 hippocampal cells to oxidative stress

Preadaptation of cultured HT22 mouse hippocampal neurons to oxidative stress prevented cell damage induced by severe oxidative stress. This protection manifested in a decrease in metabolic disturbances in neurons. Adaptation of neurons to oxidative stress was accompanied by accumulation of HSP32 and HSP70. HSP synthesis inhibitor quercetin abolished the protective effect of adaptation under conditions of oxidative stress. Activation of HSP70 synthesis in neurons is an important mechanism for adaptive protection of cells.

Resistance to neurodegenerative brain damage in August and Wistar rats.

In Wistar and August rats characterized by different resistance to acute emotional stress we compared the resistance to neurodegenerative brain damage (model of Alzheimer’s disease) produced by administration of a neurotoxic peptide fragment (25–35) β-amyloid into the brain. August rats were more resistant to acute stress and development of neurodegenerative disorders compared to Wistar rats. This conclusion was derived from studying animal behavior in conditioned passive avoidance task and open-field test that characterize cognitive function of the brain. Administration of β-amyloid modulated the behavior of Wistar rats, which reflected the impairment of memory and orientation and exploratory activity in these animals. These disturbances in Wistar rats were accompanied by activation of lipid peroxidation in the hippocampus.

Role of extracellular and intracellular nitric oxide in the regulation of macrophage responses

We studied the role of nitric oxide in the stress response and apoptosis. Intracellular nitric oxide potentiated the stress response. However, intracellular nitric oxide suppressed the stress response in macrophages of proinflammatory and antiinflammatory phenotypes. Intracellular nitric oxide promoted apoptosis in macrophages of the proinflammatory phenotype, but inhibited this process in cells of the antiinflammatory phenotype. Exogenous nitric oxide synthesized by macrophages protected them from lipopolysaccharide-induced apoptosis. Our results indicate that nitric oxide produces various effects on the stress response and apoptosis in macrophages, which depends on modus operandi.

Adaptogen ADAPT modulates stress-induced HSP70 synthesis and improves organism's resistance to heat shock

The effect of the herbal adaptogen ADAPT on the basal and heat shock-induced synthesis of HSP70 and organisms resistance to heat shock is studied. It is shown that ADAPT decreases accumulation of these proteins in the myocardium and promotes their accumulation in the liver. ADAPT has no effect on arterial pressure but prevents its drop induced by heat shock and markedly increases the survival rate of experimental animals. These data agree with the hypothesis that the effect of ADAPT on the synthesis of HSP70 is an important component of its protective action.

SP-D-Dependent Regulation of NO Metabolism in Lipopolysaccharide-Stimulated Peritoneal Macrophages

This work was designed to study the role of surfactant protein D in the regulation of NO synthesis by “non-alveolar” microphages. We evaluated whether the effects of surfactant protein D depend on the phenotype of macrophages. In the absence of surfactant protein D, the LPS-induced iNOS response was shown to decrease in macrophages of native and proinflammatory phenotypes by 30%, and in macrophages of the antiinflammatory phenotype (by 63%). Under the influence of lipopolysaccharide in high doses (500 ng/ml), NO2∸ production by mouse macrophages without surfactant protein D was reduced in native cells (by 25%), but increased in proinflammatory (by 40%) and antiinflammatory phenotypes (by 12% compared to mouse macrophages with surfactant protein D). Our results suggest that surfactant protein D is involved in the immune response in the whole organism, but not only in the lungs. The effect of surfactant protein D depends on the phenotype of macrophages.