Influence of the antioxidant status on the characteristics of lipids in tissues of animals after acute irradiation with sublethal doses

The effect of the acute exposure to sublethal doses of X-rays on the interrelation between parameters of the lipid peroxidation regulatory system (lipid antioxidative activity, AOA; peroxide amount, lipid composition) was studied in liver, spleen and blood erythrocytes of CBA and SHK mice and rats within 1 month after irradiation. The reverse correlation between the lipid AOA values and the initial peroxide amount in lipids of the CBA mice spleen was found. The coefficient of the linear regression of this correlation for the exposed mice was 1.8-fold higher as compared with control. The correlative dependence between the ratio of the sums of the more readily to more poorly oxidizable phospholipid and the ratio of phosphatidyl choline to phosphatidyl ethanolamine content in phospholipids of liver and blood erythrocytes was revealed. The direction (the phospholipids of the rat liver) or the value of the linear regression coefficient of that correlation were different for groups of the exposed and control animals, especially in the blood erythrocytes. Thus, the different sensitivity of examined characteristics of lipids and the possibility of their normalization in the dependence on the lipid AOA value cause the conversion of the lipid peroxidation regulatory system in organs and blood erythrocytes of the exposed animals to the other scale of the functioning.     

Modifying properties of 2,5-diphenyloxazole during low-dose X-ray exposure of mice

The ability of 2,5-diphenyloxazole (DPO) to modify biological consequences of the X-rays irradiation of mice was studied with a dose of 16 cGy at the administration of the agent in a wide range of concentrations before or after irradiation was studied. It was shown that the administration of the agent in doses 9.9 x 10(-3)-9.8 mg/kg 35-60 min before irradiation causes a reliable decrease in the spleen mass within 1 month after the action; for the dose 1 mg/kg, it causes the tendency to decrease of the content of lipid peroxidation (LPO) products; the dose 9.8 mg/kg causes a decrease in the cell-free DNA amount in blood plasma of mice. The administration of DPO before irradiation causes changes in the scale and direction of the correlation between the DNA and LPO products contents in blood plasma of irradiated mice compared with the control. The administration of DPO 15-60 min after irradiation do not cause any reliable changes in the investigated parameters. The aviability of the study of the radioprotective properties of the DPO derivatives as agents with a nontraditional character of action is supposed.     

A new approach to assessment of biological consequences of exposure to low-dose radiation

A high sensitivity of characteristics of the lipid metabolism in erythrocytes to exposure to low doses of gamma- and X-rays was found; the changes in lipid peroxidation (LPO) of blood components were persistent, which substantially influenced the development of biological consequences of low doses of radiation. The effect of low doses of radiation on the interrelation between the LPO intensity in blood plasma and the lymphocyte DNA structural integrity or the cell-free DNA content in animal blood plasma was found. Different sensitivity of the examined parameters (neither normalization nor linear dependence on a dose rate was found) implies the transition of the LPO regulatory system to another level of functioning due to scale changes of interrelations between the examined parameters under influence of low doses of radiation. These findings make possible to assess biological consequences of radiation factor for animal groups by the scale changes of interrelations between the examined characteristics in blood plasma.     

Regulation of lipid oxidation and structural state of the nuclear membrane after the irradiation of tumor-bearing animals

Changes of antioxidative activity (AOA), lipid composition and microviscosity of different membrane regions in tumor cell nuclei and in the liver of tumor-host with Ehrlich ascite carcinoma (EAC) after irradiation were studied. On the basis of the obtained data the analysis of the control system of lipid oxidation in the membrane was carried out. This control system involves a relationship between AOA changes, lipid composition, their oxidative ability and the nuclear membrane structure. It was shown that after irradiation the control system in the nuclei of tumor cells had the same state as before irradiation and was different from the normal one. The control system in the nuclei of tumor-host liver after irradiation starts to work in a regime which is characteristic of irradiated cells. It was shown that the principle difference in the control system functioning in tumor and tumor-host nuclei disappeared after irradiation.     

Correlation of phospholipid composition and physicochemical characteristics of lipids in tissues of the root vole <Emphasis Type="Italic">Microtus oeconomus</Emphasis> of different ages

There was performed a comparative analysis of phospholipids and of lipid physicochemical characteristics in spleen, blood erythrocytes, and liver of the root voles caught in the natural environmental habitation at different phases of the population cycle, as well of the animals born and raised throughout the entire live in vivarium, depending on the animals’ sex and age. The age-related changes in the phospholipid composition have been established to correlate with lipid physicochemical characteristics, while the scale and direction of the changes depend on the tissue functional role, the initial level of the antioxidative activity (AOA) of its lipids, and sex of the animals. In the process of the organism aging, parameters of the system of regulation of lipid peroxidation change not unidirectionally; in group of animals of the same age, individuals with different biochemical characteristics can be present. Under natural conditions of habitation the degree of expression of age-related changes is modified by populational factors.     

Radioprotection by whole body hyperthermia: possible mechanism(s)

Studies were carried out to gain an insight into the mechanisms underlying WBH induced radioprotection. The plasma levels of IL-1α, IL-6, TNF-α and GM-CSF, were elevated in WBH treated mice between 2 and 6 h after treatment. The total nucleated cell count of hemopoietic tissues such as spleen, thymus, bone marrow and peripheral blood showed drastic reduction without recovery until death in mice treated with TBI. However, the nucleated cell count in the above tissues showed significant recovery after initial drop in WBH and WBH+TBI treated groups and reached to a normal level by day 7 and day 28, respectively. The total WBC and RBC count in peripheral blood recovered to a control level by day 28 after treatment. Significant number of endogenous spleen colonies were detected, 14 days after TBI in WBH pre-treated mice whereas no such spleen colonies could be detected in TBI treated group. The transplantation of bone marrow derived from control, WBH, TBI and WBH+TBI treated groups of mice to lethally irradiated mice (8 Gy) showed formation of spleen colonies only in mice which received bone marrow from control, WBH and WBH+TBI treated groups. Transplantation of the bone marrow from these groups of mice resulted in prolonged survival of lethally irradiated mice as compared to mice receiving bone marrow from TBI treated mice. These results seem to suggest that WBH induced radioprotection of mice could be due to immunomodulation manifested through induction of cytokines responsible for protection and proliferative response, leading to accelerated recovery from hemopoietic damage-a major cause of radiation induced death.     

Mutant copies of mitochondrial DNA in tissues and plasma of mice subjected to X-ray irradiation

Impairments of mitochondrial genome are associated with a wide spectrum of degenerative diseases, development of tumors, aging, and cell death. We studied the content of mitochondrial DNA (mtDNA) with mutations and the total content of mutations in the brain and the spleen of mice subjected to X-ray irradiation at a dose of 1–5 Gy at 8–28 days after treatment. In these mice, we studied the number of mutant copies of extracellular mtDNA (ec-mtDNA) and its total content in blood plasma. We estimated mutations in control and irradiated mice using cleavage of heteroduplexes prepared by hybridization of PCR amplicons of mtDNA (D-loop region) mediated by CEL-I endonuclease, an enzyme that specifically cleaves unpaired bases. Changes in the total number of mtDNA copies relative to nuclear DNA were assessed by real time PCR using the ND-4 and GAPDH genes, respectively. We found that the number of mutant mtDNA copies was significantly increased in the brain and the spleen of irradiated mice and reached the maximum level at the eighth day after treatment; it then decreased by the 28th day after treatment. In nuclear genes similar to mutagenesis, mutagenesis of mtDNA in the brain and spleen tissues linearly depended on irradiation dose. In contrast to mutant nuclear genes, most mutant mtDNA copies were eliminated in the brain and spleen tissues, whereas the total content of mtDNA did not change within 28 days after irradiation. Our data show that, during this period, a high level of ec-mtDNA with mutations was observed in DNA circulating in blood plasma with the maximum level found at the 14th day. We suppose that mutant mtDNA copies are eliminated from cells of animals subjected to irradiation during the posttreatment period. Higher content of ec-mtDNA in blood plasma can be considered as a potential marker of radiation damage to the body.     

Effects of a 50 Hz electric field on plasma lipid peroxide level and antioxidant activity in rats

The effects of exposure to extremely low frequency electric fields (ELF EFs) on plasma lipid peroxide levels and antioxidant activity (AOA) in Sprague-Dawley rats were studied. The test was based on comparisons among rats treated with a combination of the oxidizing agent, 2,2'-azobis(2-aminopropane) dihydrochloride (AAPH) and 50 Hz EF of 17.5 kV/m intensity for 15 min per day for 7 days, AAPH alone, EF alone or no treatment. EF significantly decreased the plasma peroxide level in rats treated with AAPH, similar to treatment by ascorbic acid or the superoxide dismutase. Ascorbic acid increased AOA; however, EF and superoxide dismutase did not change AOA compared with sham exposure in stressed rats. No influence on the lipid peroxide level and AOA in unstressed rats was observed with EF exposure alone. Although the administration of AAPH decreased AOA, this decrease did not change when EF was added. These data indicate that the ELF EF used in this study influenced the lipid peroxide level in an oxidatively stressed rat.     

The antiradiation properties of the ecdysteroid-containing compounds

The antiradiation properties of the ecdysteroid-containing preparations ("serpisten" and inokosterone) are studied under their application before or after the 22.6 cGy chronic low intensity gamma-irradiation of mice. It is shown that the antiradiation of these compounds depend on the dose of preparations and time of the application before or after irradiation of mice. "Serpisten" prevented the decrease of the growth of the body mass of irradiated mice. The normalization of the phospholipid composition of the mice liver and blood erythrocytes for the most investigated parameters revealed under the application of this compound at the dose of 50 mg/kg after the irradiation of animals. The capacity of "serpisten" to decompose of peroxides is shown in vitro. Inokosterone had the certain anabolic properties, caused the normalization of the total peroxidase activity of blood and intensity of the lipid peroxidation (LPO) in brain and in liver, and also the repair of the interrelation between the LPO intensity and catalase activity in the irradiated mice liver. The obtained results allow to conclude that the antiradiation properties of the ecdysteroid-containing preparations under the chronic low intensity irradiation of animals at the low dose due to their capacity to depend on the LPO regulatory system parameters.     

Antioxidative activity of plasma membrane lipids of liver cells and its change after irradiation

Antioxidative activity (AOA) of lipids was revealed in plasma membranes of rat liver cells. The dynamics of its change after total-body X- irradiation with a dose 7.65 Gy was followed up. The authors discuss the relationship between the disorders in AOA and lipid content of surface membranes of liver cells in the exposed body and their role in radiation membrane effects.     

小鼠低剂量辐射损伤模型的初步研究

目的:对小鼠低剂量辐射损伤模型进行初步研究并筛选敏感检测指标.方法:实验分7组,1组为正常组,其余6组用XHA600直线加速器射线照射,每组取一部分小鼠于照射后2、4、8、16h测定红细胞(RBC)、白细胞(WBC)、血小板(PLT)和血红蛋白(HGB)含量;测定小鼠肝脏和脾脏重量及其组织中的超氧化合物歧化酶(SOD)和丙二醛(MDA)含量;剩余小鼠于4周后观察骨髓切片中血细胞变化.结果:照射后4h测定血常规,发现累积辐射0.4Gy组小鼠RBC有降低趋势,WBC、HGB显著降低,PLT显著升高;肝脏、脾脏的湿质量显著降低;小鼠肝脏组织中MDA的含量显著升高、SOD的活力显著降低;4周后小鼠骨髓细胞的病理改变与单次照射剂量相关,单次较大剂量(如0.6Gy)照射对骨髓细胞影响较大,在4周观察期不能自身恢复,而多次累积照射对骨髓细胞病理改变较小.结论:小鼠低剂量辐射损伤模型的最佳造模剂量为累积照射0.4Gy即每次照射100mGy,间隔一天,连续照射4次.     

Influence of the chronic gamma-irradiation at the low doses during the near ontogenesis periods on the oxidative processes in rodent organs

It is shown that the effect of the low intensity gamma-irradiation at the dose of 5.5 cGy during the 4 months including the antenatal period causes the most substantial changes of the peroxide content in the liver and in brain lipids and of TBA-reactive substances amount in organs and blood plasma of tundra vole F2 which are reproduced from parents during long-term inhabiting on the Ra-contaminated area in the Komi Republic. The consequences of the chronic gamma-irradiation at the doses of 4 cGy (the dose rate is 5 mR/h) and 31 cGy (the dose rate is 40 mR/h) are studied by the morphophysiological and by biochemical parameters in organs of mice CBA (males) within 3 months after exposure. The change of the scale of the interrelation between the liver and body masses and also between the sums of the more easily to the more poorly oxidizable fractions and the phosphatidyl choline to phosphatidyl ethanolamine ratio in the liver phospholipids in groups of the irradiated mice is found as compared with that in the control group. The absence of interrelation between the lipid peroxidation process intensity and the catalase activity in the murine liver and also between the disbalance of the biochemical functions and the dose rate and/or the dose of the gamma-irradiation is revealed. The analysis of the data obtained allow to conclude that the chronic gamma-radiation under low intensity has the systemic effect on the animal organism causing of its function on the other level.     

Effect of thymostimulin and thyroxine on lipid peroxidation and antioxidant enzyme activity in experimental hypothyrosis

In the livers and spleens of pseudoectomized, thymectomized, thymthyroidectomized mice and thyroidectomized rats there is clear regularity in the change of lipid peroxidation intensity antioxidant system and enzymes activity depending on the severity and duration of pathologic changes occurred in organism and biological significance of the removed endocrine glands in maintenance of homeostasis. Thymostimulin and thyroxin do not render a direct effect on the intensity of lipid peroxidation, but their injection to the thyroidectomized rats indirectly normalizes content of peroxidant products in tissues of liver and spleen and restores disordered metabolism processes as a result of thyroid gland ectomia.     

不同剂量的X-射线全身照射对小鼠健康状况及涎腺的影响

目的:通过直线加速器全身照射昆明小鼠建立辐射损伤模型,探索不同放射剂量对小鼠健康状况及涎腺功能和结构的影响。方法:选取八种不同剂量对昆明小鼠行体外全身照射,于照射后一个月内观察小鼠生长情况、体重变化;照射后一周、一个月检测各组小鼠血象的变化;测定放射半数致死剂量;照射后两个月,测定各组小鼠的唾液流量及唾液淀粉酶含量,并对下颌下腺组织切片行HE染色。结果:13Gy和15Gy照射组小鼠的体重逐渐下降,一周后死亡,其余组小鼠体重最终呈增加趋势。X-射线全身照射的半数致死量为10Gy。照射后一周,照射组小鼠的白细胞数目明显降低,与对照组比较有明显统计学差异(P0.01);在其他血象方面,除了7Gy组外,其他照射组与对照组比较也均有统计学差异(P0.05)。照射一个月后,各照射组小鼠的血象均恢复正常。照射后两个月,9Gy组和11Gy组小鼠的唾液流量及唾液淀粉酶含量均显著低于0Gy组,且11Gy组较9Gy组亦明显降低,差异均有统计学意义(P0.05)。随照射剂量的增加,小鼠的下颌下腺腺泡细胞数目逐步减少,结构排列紊乱,组织损伤逐渐加重。结论:X-射线全身照射引起小鼠健康状况受损,免疫功能减低,损伤程度与放射线强度呈剂量依赖性,小鼠半数致死量为10Gy,该剂量适合建立全身放射损伤模型。     

Changes in ganglioside contents, plasma sialic acid and cAMP levels in experimental hepatoma in mice

The present study was designed to assess whether changes in glycolipids and cyclic AMP contents might serve as markers for the diagnosis of malignancy in the liver. The experimental model was a transplantable murine hepatoma. Experimental mice were divided into three groups: (1) a therapeutic group, which had been transplanted with hepatoma and treated with the antimetabolism drug 5-flurouracil (0.2 mg/day i.p.), (2) a control group, which had been transplanted with hepatoma and treated with 0.2 ml 0.9% NaCl/day and (3) a normal group of mice. The ganglioside and cAMP contents in the hepatoma tissue, plasma cAMP, total- and lipid-bound sialic acid levels and red blood cell membrane sialic acid levels were determined. Results showed that the ganglioside content, total and lipid-bound sialic acid levels in the control group were significantly higher than those in the livers of normal mice (p < 0.01) while these respective values in the therapeutic group were significantly lower than those in the control group (p < 0.01). The cAMP levels of tumor tissues and plasma in the control group were lower than those in normal mice. No significant difference in red blood cell membrane sialic acid content was observed between the therapeutic and control groups though levels for both were higher than those in normal mice. These results indicate that ganglioside content and sialic acid levels in hepatoma tissues were significantly elevated, and cAMP levels in hepatoma tissues were significantly decreased during proliferation and abnormal differentiation.     

Differences in membrane lipid composition and fluidity of transplanted GRSL lymphoma cells, depending on their site of growth in the mouse

GRSL lymphoma cells were isolated from various growth sites in the host. The relative membrane lipid fluidities of these cells and of normal lymphoid cells were estimated by fluorescence polarization, using the probe diphenylhexatriene and by measuring the (free) cholesterol/phospholipid molar ratio in whole cells. The results indicate that the membrane fluidity (reciprocal of the lipid structural order) of the lymphoma cells increases in the order of their location: peripheral blood less than spleen less than mesenterial lymph node less than ascites fluid. The membrane fluidities of normal lymphocytes from thymus, mesenterial lymph node and spleen were about the same, but higher than of peripheral blood lymphocytes, and between those of the lymphoma cells from lymph node and spleen. These results are confirmed by more extensive analysis on purified plasma membranes from the splenic and ascitic GRSL lymphoma cells and from normal splenocytes and thymocytes. The significantly higher lipid order parameter found in the GRSL plasma membrane isolated from the spleen as compared to those from the ascites cells could be fully explained by the differences measured in the major chemical determinants of the fluidity, i.e., the cholesterol/phospholipid ratio, the sphingomyelin content and the degree of saturation of the fatty acyl groups of the phospholipids. It was also found that the cholesterol/phospholipid ratio in erythrocyte membranes isolated from the peripheral blood of the tumor bearers was higher than in those from normal control mice. The observed differences in membrane fluidity between distinct subsets of tumor cells may be relevant to the sensitivity of these cells to immune attack or to drugs.     

Differences in membrane lipid composition and fluidity of transplanted grsl lymphoma cells, depending on their site of growth in the mouse

GRSL lymphoma cells were isolated from various growth sites in the host. The relative membrane lipid fluidities of these cells and of normal lymphoid cells were estimated by fluorescence polarization, using the probe diphenylhexatriene and by measuring the (free) cholesterol/phospholipid molar ratio in whole cells. The results indicate that the membrane fluidity (reciprocal of the lipid structural order) of the lymphoma cells increases in the order of their location: peripheral blood < spleen < mesenterial lymph node < ascites fluid. The membrane fluidities of normal lymphocytes from thymus, mesenterial lymph node and spleen were about the same, but higher than of peripheral blood lymphocytes, and between those of the lymphoma cells from lymph node and spleen. These results are confirmed by more extensive analysis on purified plasma membranes from the splenic and ascitic GRSL lymphoma cells and from normal splenocytes and thymocytes. The significantly higher lipid order parameter found in the GRSL plasma membrane isolated from the spleen as compared to those from the ascites cells could be fully explained by the differences measured in the major chemical determinants of the fluidity, i.e., the cholesterol/phospholipid ratio, the sphingomyelin content and the degree of saturation of the fatty acyl groups of the phospholipids. It was also found that the cholesterol/phospholipid ratio in erythrocyte membranes isolated from the peripheral blood of the tumor bearers was higher than in those from normal control mice. The observed differences in membrane fluidity between distinct subsets of tumor cells may be relevant to the sensitivity of these cells to immune attack or to drugs.     

Quantitative changes in the arterial blood gases of mice following localized irradiation of the lungs

The arterial pH and partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) were evaluated in LAF 1 mice 15 and 38 weeks after localized irradiation of the animals' thoraxes. Graded radiation doses of 900 to 1200 rad were administered. These doses resulted in 0 to 100% lethality by 26 weeks (180 days) after irradiation. At 15 weeks after treatment mice receiving radiation doses which would subsequently result in lethality (by 180 days) exhibited significant reductions in their PaO2 and elevations in their PaCO2 values, respectively. However, there was no clear dose-response relationship between blood gas values and radiation dose, which may reflect the animals' ability to compensate for their poor blood gas exchange by an increased breathing frequency. At 38 weeks after irradiation the blood gas values were abnormal in mice from groups which had normal blood gas values at Week 15 (and no fatalities by Week 26) but in which animal deaths had occurred between Weeks 26 and 38. These data therefore indicated (i) that abnormal blood gas values occurred in the mice prior to fatalities resulting from the acute radiation pneumonitis syndrome and (ii) that mice surviving the initial radiation pneumonitis phase could still succumb to progressive pulmonary toxicity which was reflected by the increasing levels of animal lethality and altered blood gas tensions at the later times.     

Dependence of response reaction of root voles to low-intensity irradiation on initial state of the tissue antioxidant system

There has been studied the response of antioxidant (AO) reaction of the tissue system of the root voles Microtus oeconomus Pall., whose parents belonged to the populations long inhabiting the Republic Komi regions with different degrees of radioactive contamination, on an additional irradiation at low doses. Differences have been revealed in the phospholipid content, activity of AO defense, intensity of processes of lipid peroxidation (LPO) in tissues of the offspring of voles caught in the control and contaminated regions. It has been revealed that direction and degree of changes in the offspring tissues after the additional action are determined by the parameter value in the non-irradiated animal group. Intensity of the LPO processes in liver and brain was leveled after the long low-intensity irradiation. The obtained data and analysis of literature indicate that at predicting effects of chronic action of low doses of a damaging factor both in experiment and in the natural habitation, it is necessary to take into account initial characteristics of biological objects.     

The absence of adaptive changes in tissue activities of glutathione-S-transferase, superoxide dismutase and catalase following selenium and vitamin E supplementation in subjects with low selenium status

Three groups of New Zealand women were given daily in a double blind randomised study, 200 micrograms Se as sodium selenite, 170 mg alpha-tocopherol or a placebo for 4 wk. Activities of glutathione-S-transferase, superoxide dismutase and catalase were assayed in erythrocytes, plasma and platelets and in liver and muscle biopsy tissues. No changes in activities of any of these tissue enzymes were observed in any of the three groups. There were also no changes in non-selenium dependent glutathione peroxidase activities in liver or plasma. The lack of changes in any of these enzymes following selenium supplementation suggests that adaptive changes to the low selenium status of these subjects had not occurred through these lipid peroxidation defense mechanisms.