The effect of 3 months feeding with diets of different protein and sucrose content (9 % casein -f 70 % sucrose vs. 18 % casein + 61 % sucrose) on the development of diabetic nephropathy and changes in serum lipid spectrum was investigated in rats with insulin-dependent diabetes (streptozotocin 45 mg.kg-1). Metabolism of diabetic animals (before the nutritional regimen) was characterized by hyperglycaemia, moderate hyperlipidaemia, lipid accumulation in the liver and elevated creatinine concentration in the blood. Kidney weight and protein content were not significantly changed. Histological picture of kidneys showed initial changes of glomerular structure. After three months hyperlipoproteinaemia was more accentuated in animals given either of the two diets, the kidneys were hypertrophic with a higher protein content and displayed morphological changes of diabetic nephropathy. Animals given the low-protein diet developed smaller morphological changes both in glomeruli and tubuli. The study indicates that dietary protein and not hyperlipoproteinaemia is the major factor, which may significantly influence the progress of diabetic nephropathy.
The brain is widely responsive to gonadal hormones. The functional significance of ovarian hormones in the brain is evident from biochemical studies indicating that estradiol or progesterone treatment of testectomized rats produces changes of antioxidant enzyme activities. The effect of estradiol benzoate (EB) and progesterone (P) in the control of antioxidant (AO) enzyme activities was studied in the brain of adult male Wistar rats. The activities of catalase (CAT), glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST) and glutathione reductase (GR) were measured in appropriate subcellular fractions, prepared from brains of animals belonging to various experimental groups. These groups were designed with the intention to follow changes in enzyme activities 2 h or 24 h after systemic administration of 5 g EB or 2 mg P to testectomized (TX) animals. The obtained results show that both EB and P increase CAT activity, whereas EB decreases GSH-Px, GST and GR activities. These findings clearly show the modulatory role of EB and P in the control of enzymes responsible for the protection of rat nerve cells against oxidative damage caused by free oxygen radicals., S. B. Pajović, Z. S. Saičić, M. B. Spasić, V. M. Petrović., and Obsahuje bibliografii
The effect of various photoperiods on circadian rhythms of chosen parameters was investigated in laboratory rats. SPF male Wistar rats were adapted for six weeks to artificial light-dark cycles (LD 8 : 16, 12 : 12, 16 : 8). The light was switched on at 07.00 h in all regimens. The rats were killed at 3-hour intervals within 24 h, the serum concentration of corticosterone, insulin,glucose, food and water intake was determined. The external and computative acrophases of corticosterone varied in every photoperiod being dependent on the duration of light, the mesor values decreased in LD 16 : 8 in comparison with other photoperiods. The external acrophase of insulin was located 4 h after light onset in LD 8 : 16 and 12 : 12, in LD 16 : 8 one hour before light onset. The mesor values were approximately equal in all photoperiods. The circadian rhythms of glucose were similar in all regimens. Circadian variation of food and water consumption culminated at the same time in all regimens, the amount of food consumed in light increased with the light duration. Various photoperiods remarkably influenced circadian oscillations of corticosterone and in part food and water intake which could be considered as photoperiodic traits.
The role of age in the development of two-kidney, one-clip (2K1C) renal hypertension was evaluated. Blood pressure response to aortic constriction was more pronounced in young rats although the alterations of renal renin activity and body fluid volumes were greater in adult ones. Obtained results suggested that 2K1C renal hypertension is maintained by reciprocal interaction of renin-angiotensin system and body fluid volume alterations only in adult rats. In young rats other factors might be more important.
Metabolism of palmitate-14C was studied in the rat liver and muscle incubated with 1 mmol.1-1 tolbutamide in vitro experiments: Tolbutamide reduces the utilization of free fatty acids in the liver by inhibiting their uptake, incorporation into total lipids, and oxidation to 14CC>2. Tolbutamide stimulates the incorporation into the triacylglycerol fraction in individual liver lipid fractions and inhibits the incorporation into the free fatty acid fraction. As in the liver, tolbutamide inhibits the uptake, incorporation into total lipids, and oxidation to 14C02 in the muscle. In individual lipid fractions, tolbutamide only inhibits the incorporation of palmitate into cholesterol esters. It can be concluded that tolbutamide directly interferes with fatty acid metabolism and thus improves glucose utilization and insulin resistance.
For more than sixty years lith ium carbonate has been used in medicine. However, during its administration different side effects including oxidative stress can occur. Selenium belongs to essential elements possessing antioxidant properties. This study aimed at evaluating if selenium co uld be used as a protective adjuvant in lithium therapy. The experiment was performed on four groups of Wistar rats: I (control), II (Li), III (Se), IV (Li + Se) treated with saline, lithium carbonate (2.7 mg Li/kg b.w.), sodium selenite (0.5 mg Se/kg b.w.) and lithium carbonate (2.7 mg Li/kg b.w.) + sodium selenite (0.5 mg Se/kg b.w.), respectively. All substances were administered as water solutions by stomach tube for 3 or 6 weeks. Catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GP x) as well as malonyldialdehyde (MDA) were determined in brain homogenates. Lithium slightly enhanced MDA and depressed CAT and SOD after 6 weeks as well as GPx after 3 weeks. Selenium co -administration show ed tendency to restore the disturbed parameters. Selenium alone and given with lithium significantly increased GPx vs. Li- treated group after 3 weeks. Having regarded the outcomes of this study, the research on application of selenium during lithium treatment seems to be worth continuation., M. Kiełczykowska, J. Kocot, A. Lewandowska, R. Żelazowska, I. Musik., and Obsahuje bibliografii
The aim of this study was to gain more complete information about the relationships between some endogenous antioxidants and the malondialdehyde (MDA) as a marker of lipid peroxidati on, during D -galactose induced senescence. The activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and the concentrations of uric acid (UA) in plasma and MDA in erythrocyte’s hemolysate, were determined in 15 D -galactose (D-gal), treated rats and compared with 15 placebo. The activity of the erythrocyte’s CAT was found significantly increased due to the senescence. The ratio of the activities of antioxidant enzymes R =SOD/(GPx+CAT) was significantly decreased due to the sen escence and negatively correlated with the MDA ( ρ = -0.524, p=0.045). The antioxidant enzymes SOD and GPx negatively correlated with the MDA, while CAT displayed no correlation. Further, the UA positively correlated with the ratio of activities of the antioxidant enzymes R=SOD/(GPx+CAT), ( ρ =0.564, p=0.029 for senescent rats). Obtained results may contribute t o better understanding of the process of D-gal induced senescence in the erythrocytes., M. Mladenov, M. Gokik, N. Hadzi-Petrushev, I. Gjorgoski, N. Jankulovski., and Obsahuje bibliografii
Male Wistar rats were irradiated continuously with a daily dose of 0.19 Gy (120 days), 037 Gy (90 days) and 0.96 Gy (35 days) of gamma rays. An other group of rats was irradiated continuously with graded doses of gamma rays, up to total exposures ranging from 3.83-19.15 Gy. Depending on both the daily dose and total exposure, there was a decrease in phospholipid content in the thymus which correlated well with thymus weight changes. The decrease in triacylglycerol content was a less reliable sign of radiation damage. The phospholipid content reflecting the patterns of organ cellularity is a valuable indicator of the extent as well as recovery from radiation - induced injury to the thymus.
Hypoxia stimulates ventilation, but when it is sustained, a decline in the ventilatory response is seen. The mechanism responsible for this decline lies within the CNS, but still remains unknown. In this study, we attempted to elucidate the possible role of hypoxia-induced depression of respiratory neurons by comparing the ventilatory response to hypoxia in intact rats and those with denervated carotid bodies. A whole-body plethysmograph was used to measure tidal volume, frequency of breathing and minute ventilation (VE) in awake and anesthetized intact rats and rats after carotid body denervation during exposure to hypoxia (FIO2 0.1). Fifteen-minute hypoxia induced an initial increase of VE in intact rats (to 248 % of control ventilation in awake and to 227 % in anesthetized rats) followed by a consistent decline (to 207 % and 196 % of control VE, respectively). Rats with denervated carotid bodies responded with a smaller increase in VE (to 134 % in awake and 114 % in anesthetized animals), but without a secondary decline (145 % and 129 % of control VE in the 15th min of hypoxia). These results suggest that afferentation from the carotid bodies and/or the substantial increase in ventilation are crucial for the biphasicity of the ventilatory response to sustained hypoxia and that a central hypoxic depression cannot fully explain the secondary decline in VE., H. Maxová, M. Vízek., and Obsahuje bibliografii