[The ROS-generating and antioxidant systems in the liver of rats treated with prednisolone and vitamin D3].

The mechanisms of glucocorticoid-induced disturbances of liver function is currently not fully clarified. Vitamin D3 was previously shown to play an important role in the regulation of impaired oxidative metabolism and detoxification function of the liver associated with the effects of hepatotoxic compounds. The study was undertaken to define the intensity of oxidative metabolism in the rat liver and survival of hepatocytes after prolonged prednisolone administration and to assess whether vitamin D3 is capable to counter glucocorticoid-induced changes. It has been shown that prednisolone (0.5 mg per animal for 30 days) leads to 1.6-fold increase in the percentage of necrotic cells among isolated hepatocytes as compared with the control. The glucocorticoid-induced impairment of hepatocellular function was accompanied by enhanced generation of reactive oxygen species (ROS), accumulation of TBA-active products and carbonylated proteins but reduced levels of free SH-groups of low molecular weight compounds. It was demonstrated a decrease in the activities of key enzymes of antioxidant system (SOD, catalase, glutathione peroxidase), whereas the activities of pro-oxidant enzymes NAD(P)H-quinone oxidoreductase and semicarbazide-sensitive amine oxidase were shown to be increased. Vitamin D3 (and to greater extent in combination with α-tocopherol) administration (100 IU) on the background of glucocorticoid therapy caused normalizing effects on the level of ROS formation, oxidative modification of biomolecules and activity of antioxidant enzymes resulting in better survival of hepatocytes. These data suggest a potential role of vitamin D3 in the regulation of oxidative metabolism alterations related to hepatotoxic action of glucocorticoids.

[Role of PARP and protein poly-ADP-ribosylation process in regulation of cell functions].

This review focuses on the biological role of enzymes involved in posttranslational modification of proteins by their poly-ADP-ribosylation, a NAD-consuming process with an emerging key role in providing fundamental cell functions. To this end, detailed analysis of structural organization in relation to basic functions of the poly(ADP-ribose) polymerase-1 (PARP-1), the founding member of the PARP family, and other poly(ADP-ribose) polymerase isoforms is presented here. These include the current views on the role of PARP family enzymes and processes of poly-ADP-ribosylation of proteins in chromatin structure remodeling, DNA damage repair, regulation of gene expression, and integration of cellular signaling pathways. Considerable attention is paid to the involvement of PARP in cellular functions, particularly in cell division, intracellular transport of macromolcules, proteasomal protein degradation, immune response and caspase-independent necrotic pathways defined as necroptosis (programmed necrosis). In the light of the remarkable successes that have been reported for treating inflammatory disorders and cancer with different classes of PARPs inhibitors, we discuss the prospects of targeting PARPs with therapeutic purposes.

[Na+, K+-ATPase activity and serotonin transport in the rat brain synaptosomes fractions after acute 1,2-dichloroethane intoxication and nicotinamide administration]. / Na+, K+-ATR-azna aktyvnist' ta transportuvannia serotoninu u fraktsiï synaptosom holovnoho mozku shchuriv za hostroï intoksykatsiï 1,2-dykhloretanom ta vvedennia nikotynamidu.

Alterations of Na+,K+-ATPase activity and serotoninergic system functioning were investigated in brain synaptosomes fractions of rats under experimental acute 1,2-dichloroethane (DChE) intoxication. It was shown that Na+,K+-ATPase activity was markedly increased (by 41,8%) in a period of 24 h after DChE intoxication and decreased (by 27%) after 48 h intoxication. The level of [2-14C]-serotonin uptake by synaptosomes was progressively diminished after 24 and 48 h after DChE injection whereas the activity of monoamine uptake proved to be unchanged. Nicotinamide (200 mg/kg of body weight) was administered to rats subjected to DChE 1, 24 and 36 h after poisoning. The treatment of rats with nicotinamide resulted in some normalization of brain synaptosomal Na+, K+-ATPase activity and serotonin uptake controlled at 48 h after DChE intoxication.

[Activity of antioxidant enzymes in enterocytes of the small intestine and blood cells after ionizing irradiation and administration of vitamin E in rats]. / Aktyvnist' fermentiv antyoksydantnoho zakhystu v enterotsytakh tonkoho kyshechnyka ta klitynakh krovi za ionizuiuchoho oprominennia ta vvedennia shchuram vitaminu E.

The long-term influence of low X-ray irradiation increases lipid peroxidation (LP) in radiosensitive (bone marrow, enterocytes of small intenstine) and in relatively radioresistant blood cells (erythrocytes). The activation of antioxidant system enzymes in observed cells does not decrease LP intensity. We concluded that additional administration of alpha-tocopherol provided the decrease of the first and end products of LP in the observed tissues mostly in the beginning of the experiment. Antioxidant effect of the preparation is more significant in cells with high proliferative activity but normal activity of enzymes was not determined.