Regulation of lipid peroxidation in the retina under the effect of bright light.

Changes in LPO intensity under the effect of exposure to bright light and the possibility of their correction with antioxidants were studied on rabbits with diabetic retinopathy. It was found that enhanced LPO caused by exposure to bright light in rabbits with diabetic retinopathy can be corrected with antioxidants. Phenosan potassium salt, α-tocopherol, and oxypyridine were more effective than SOD and taurine in preventing MDA accumulation. A complex of natural and synthetic antioxidants was most efficient in correcting LPO under conditions of exposure to bright light.

Use of natural antioxidants for the correction of changes in general and local parameters of lipid peroxidation and antioxidant defense system during experimental eye burn.

The effect of natural antioxidants in grade III chemical eye burn was studied in experiments on rabbits at various stages of burn disease. The use of histochrome, Gingko Biloba, and diquertin in combination with complex drug therapy decelerated the decrease in the antioxidant potential of tear fluid and blood plasma. This treatment was also followed by a decrease in the concentration of end products of free radical oxidation.

Antioxidant potential of tear fluid and blood plasma in rabbits with grade III chemical eye burn at various stages of burn disease.

The antioxidant potential of tear fluid and plasma in rabbits with chemical eye burn of grade III was measured at various stages of burn disease. Eye burns were accompanied by depletion of the antioxidant system in tear fluid and plasma and impairment of antioxidant defense in the whole organism. These changes contribute to activation of free radical lipid peroxidation. The pathological changes in the organism and eye were most pronounced at the stage of trophic disturbances.

[Features of lipid peroxidation in the vitreous body and retina during intravitreal hemorrhaging in dithiosone-induced diabetes]. / Osobennosti perekisnogo okisleniia lipidov steklovidnogo tela i setchatki pri intravitreal'nom krovoizliianii na fone ditizonovogo diabeta.

It has been stated that in experimental dithiazone-induced diabetes lipid peroxidation is intensified in vitreous body and retina of the rabbits' eyes. The increase of LP in vitreous body and retina during intravitreal hemorrhage due to experimental diabetes was controlled by antioxidants.

[The role of melanin in regulating free radical processes in the epithelial eye pigment in acute hypoxia]. / O roli melanina v reguliatsii svobodnoradikal'nykh protsessov v pigmentnom épitelii glaza pri ostroi gipoksii.

Retinal response to the acute hypoxia and reoxygenation were shown to be independent of melanin presence in the eye pigmental epithelium (PE), i.e. in the retinas of both pigmented animals and albinos hypoxia survived an increase in the content of hydroperoxidases and malonyl dialdehyde; subsequent reoxygenation resulted in a more considerable accumulation of lipid peroxidation (LPO) products in both retinal types. Nevertheless under reoxygenation the number of malonyl dealdehyde became below the norm in PE of melanin-containing animals, but not in the albinos. At the same time acute hypoxia increased by 31% the electron spin resonance (ESR) uptake in the pigmented animals. Subsequent reoxygenation inconsiderably suppressed the intensity of the ESR signal. Under the above conditions pretreatment with Na2SeO3 increased the intensity of PE ESR uptake more than 2.5 times with following retrieval to the control level at the 20th minute of reoxygenation. We suggest that under hypoxia with subsequent reoxygenation the melano-protein granules favour regulation of LPO in PE, but not in other retinal layers, the findings being considerably different from those related to potent light effect.

[Antiradical activity of retinal lipids under illumination]. / Antiradikal'naia aktivnost' lipidov setchatki pri ee osveshchenii.

Antiradical activity (ARA) of lipids from cattle in norm and under strong illumination with and without antioxidants was studied by chemoluminiscence method of initiated ethylbenzol oxidation. Lipids ARA from the retina in norm was established to be sufficiently high-3.0 X 10(6) l/mol. s. alpha-tocopherol was proposed to be the main component influencing lipids ARA. Under strong illumination (15 min:, 0.8 J/s) lipids ARA decreased due to intensification of lipid peroxidation (the content of MDA was increased). The antioxidants (alpha-tocopherol, potassium phenozan, ionol) in 0.1 mM concentrations increased the ARA of lipids in spite of light action. Changes in overall inhibitory activity of natural antioxidants and MDA content was antibat.

[The role of selenium in the regulation of lipid peroxidation in biological membranes and glutathione peroxidase activity]. / Uchastie selena v reguliatsii perekisnogo okisleniia lipidov biomembran i aktivnost' glutationperoksidazy.

The antioxidative effect of selenium cannot be exclusively due to the functioning of the selenium-dependent glutathione peroxidase mechanism of utilization of various hydroperoxides. This hypothesis is based on the following experimental evidence. Selenium ions are readily incorporated into animal organs and tissues immediately after injection (2 hours) as well as into cell organelles and cytosol where they inhibit lipid peroxidation. The activity of glutathione peroxidase (EC 1.1.1.19) in rat liver and guinea pig cytosol is thereby unchanged but increases drastically after 12 hours reaching a maximum an the 3rd-4th day. The effectiveness of lipid peroxidation inhibition does not increase under these conditions. Although the glutathione peroxidase activity is absent in the nuclei and microsomes, exogenous selenium inhibits lipid peroxidation in these organelles. The activity of the rat liver cytosolic enzyme markedly exceeds that of its guinea pig counterpart. However, lipid peroxidation in guinea pig liver occurs less intensively than that in rat liver cytosol.

[The Na, K-ATPase activity of the separate structural components of the guinea-pig visual system in hypoxia]. / Na, K-ATFaznaia aktivnost' otdel'nykh strukturnykh komponentov zritel'noi sistemy morskikh svinok pri gipoksii.

Different degree of sensitivity to acute hypoxia in vivo has been shown in guinea-pig pigmented epithelium, retina and visual cortex Na, K-ATPase. The highest degree of the enzyme activity inhibition has been noted in the pigmented epithelium (more than 3 times), lower inhibition-in visual cortex (26%) and the lowest-in the retina (18%). In contrast to Na, K-ATPase, hypoxia effect on Mg-ATPase resulted in both inhibition and activation of the enzyme in all 3 structures. Reoxygenation following acute hypoxia increases Na, K-ATPase activity inhibition in the retina and visual cortex. But under reoxygenation the enzyme activity is recovered in the pigmented epithelium. Preliminary administrations of vitamin E completely prevented Na, K-ATPase activity inhibition in all studied structures.

[The action of émoksipin on the basal activity of cyclic nucleotide phosphodiesterase and on the late receptor potential of the isolated retina]. / Deistvie émoksipina na bazal'nuiu aktivnost' fosfodiésterazy tsiklicheskikh nukleotidov i pozdnii retseptornyi potentsial isolirovannoi setchatki.

The influence of emoxypin (derivate of 3-hydroxypyridine) upon the late receptor potential (LRP) and activity of the cyclic 3',5'-nucleotide phosphodiesterase (PDE) have been investigated. The inhibition of PDE and increase of the amplitude of LPR have been shown. The curve (RP as a function of the stimulus light intensity) was moved towards the lesser lighting and the time of the achievement of the maximum was increased. Thus, emoxypin produces an effect on the LRP like classical inhibitors of PDE. It is suggested that increase of the functional activity of the retinae upon the influence of emoxypin in caused by the influence of the one towards the system of the cyclic nucleotides.

[Lipid peroxidation and ATPase activity in synaptosomal and mitochondrial fractions of the brain in hypoxia]. / Perekisnoe okislenie lipidov i aktivnost' ATFaz v sinaptosomal'nykh i mitokhondrial'nykh fraktsiiakh mozga pri gipoksii.

Acute hypoxia was accompanied by intensification of lipid peroxidation in synaptosomal and mitochondrial rat brain fractions as well as by inhibition of Na+, K+- and Mg2+-ATPases. Preadministration of antioxidants vitamin E and ionol into animals prevented distinctly the increase in lipid peroxidation rate, while the ATPases activity was unaltered. Inhibition of the ATPases may be considered as a result of impairing effect of the lipid peroxidation products, which appears to be of importance for structure-functional deteriorations of the nervous system in hypoxia.

[Lipid peroxidation in the synaptosomal and mitochondrial fractions of separate brain structures in hypoxia]. / Perekisnoe okislenie lipidov v sinaptosomal'noi i mitokhondrial'noi fraktsiiakh otdel'nykh struktur mozga pri gipoksii.

The paper studies intensification of lipid peroxide oxidation in separate brain structures (the medulla oblongata, cerebellum, visual and sensomotor cortex), synaptosomal and mitochondrial fractions under hypoxia. It has been established that acute hypoxia increases accumulation of lipid peroxidation (LPO) products, hydroperoxide and malonyl dialdehyde. Intensification of LPO in synaptosomes and mitochondria is more pronounced as compared to the whole structures. Preliminary treatment with antioxidants (vitamin E and ionol) considerably suppressed LPO intensity under both hypoxia and hypoxia with reoxygenation. Intensification of LPO in synaptosomes and mitochondria is suggested to be the key point in structural-functional disturbances of the nervous system under hypoxia and ischemia.

[Inhibition of lipid peroxidation by antioxidants in the vitreous body during hemorrhage]. / Ingibirovanie perekisnogo okisleniia lipidov antioksidantami v steklovidnom tele pri krovoizliianii.

The paper was to investigate the character of malonic dialdehyde content shifts in the vitreous body under the effect of potassium fenosane, oxipyridinchlorhydrate (OPChH), superoxidedismutase, sodium diethylditiokarbamat (DDTK), forming complex with copper under the experimental hemorrhage. Decrease in LPO speed shown after potassium fenosane administration was considerable under retrobulbar administration. More pronounced inhibition of LPO reaction under the hemorrhage was noted in combination of antioxidants with superoxidedysmutase.

[Role of monoaminoxidase in the intensification of peroxidation of lipids in mitochondria during experimental myocardial necrosis]. / O roli monoaminoksidazy v intensifikatsii perekisnogo okisleniia lipidov mitokhondrii pri éksperimental'nom nekroze miokarda.

The relationship between lipid peroxidation and rat heart mitochondrial monoamine oxidase activity was studied in experimental myocardial necrosis induced by adrenaline injection. It has been established that both the intensity of peroxidation and the activity of monoamine oxidase in mitochondria from adrenaline-injured rat myocardium were essentially increased. The preliminary administration of antioxidants (vitamin E and ionol) was shown to decrease both the intensity of lipid peroxidation and the activity of monoamine oxidase. It is suggested that intensification of lipid peroxidation which is considered to be the main pathogenic factor in ischemic myocardial injury depends on mitochondrial monoamine oxidase activity. Protective effects of antioxidants are realized by the action on two subsequent chains during the formation of active oxygen forms and destruction of lipid peroxidation products.

[Effect of the functional groups of tocopherol molecules on lipid viscosity of mitochondria]. / Vliianie funktsional'nykh grupp molekul tokoferolov na viazkost' lipidov mitokhondrii.

The influence of tocopherol and its analogue (oxychroman) on the microviscosity of mitochondrial lipids was studied, using spin labels. The viscosity of the lipid bilayer was shown to enhance with the increase in the antioxidant content in the membrane. Small concentrations of alpha-tocopherol (10(-5)-10(-6) mol/l) were shown to increase, while large concentrations (10(-3)-10(-4) mol/l) decreased the fluidity of the lipid bilayer. The influence of alpha-tocopherol on fluidity of the lipid bilayer depending on its concentration could be realized in two ways: by direct influence on the lipid bilayer and via reception. It was shown that alterations in the viscosity of the lipid bilayer depend on chroman cycle of tocopherols, while the temperature of structural transfer and effective energy of activation depend on the lateral phytyl chain.

[Possible mechanisms of the activation of the lipid peroxidation reaction in the vitreous body in hemorrhage]. / O vozmozhnykh mekhanizmakh aktivatsii reaktsii perekisnogo okisleniia lipidov v steklovidnom tele pri krovoizliianii.

It has been established that one of the mechanisms of lipid peroxidation intensification is mediated by metals of variable valency, hemin compounds and phospholipids carried into the vitreous body by blood.

[Effect of visual cortex stimulation on lipid peroxidation in the rabbit retina]. / Vliianie stimuliatsii zritel'noi kory na perekisnoe okislenie lipidov v setchatke krolika.

Chronic experiments on rabbits have shown that visual cortex stimulation resulted in intensified lipid peroxidation in the retina with the parallel decrease of electroretinogram amplitude parameters. The transsection of the optic nerve resulting in the elimination of retinal corticofugal inputs diminished the accumulation of lipid peroxidation products in the rabbit retina during light adaptation. Preliminary insertion of antioxidants to animals (vitamin E and ionol) prevents the inhibitory effect of the cortex on the function of the retina. The data obtained are discussed in view of possible involvement of lipid peroxidation in the retina into the realization of the regulating influence of the cortex on the function of the retina.

[Phylo- and ontogenic characteristics of lipid peroxidation in the retina of vertebrates]. / Issledovanie filo- i ontogeneticheskikh osobennostei perekisnogo okisleniia lipidov setchatki pozvonochnykh zhivotnykh.

Phylo- and ontogenetic aspects of lipid peroxidation and antioxidative enzyme system in the retina of vertebrates were studied. It was established that both the intensity of lipid peroxidation and the activity of glutathione peroxidase in the retina of different vertebrate animals (carp, frog, tortoise, pigeon, rabbit) considerably diminished with evolution. The differences in the intensity of lipid peroxidation and the activity of glutathione peroxidase between dark- and light-adapted retinas also decreased depending on the level of the development. The activity of glutathione peroxidase in the retina of chick embryos was found only at the end of the incubation period.

[Lipid peroxidation in external and internal mitochondrial membranes during anoxia]. / Perekisnoe okislenie lipidov v naruzhnykh i vnutrennikh membranakh mitokhondrii pri anoksii.

Accumulation of lipid peroxidation (LPO) products was investigated in external and internal membranes of mitochondria with anoxia. The increase in LPO intensity in mitochondria membranes during hypoxia was shown to be more expressed in external membranes, with an active involvement of phospholipase A2 in the process revealed. Greater LPO intensity and lability of lysosomal membranes caused by contacts with mitochondria with anoxia have been established.