Selenium-mediated biochemical changes in Japanese quails : Tissue uptake and distribution of injected(75)selenium labeled sodium selenite in relation to dietary selenium status.
TL;DR: The tissue uptake and distribution of injected [75Se]-sodium selenite as a variance with time and as influenced by dietary selenium status was followed in the tissues of Japanese quails.
Abstract: The tissue uptake and distribution of injected [(75)Se]-sodium selenite as a variance with time and as influenced by dietary selenium status was followed in the tissues of Japanese quails,Coturnix coturnix japonica. Quails maintained on a low selenium semipurified (basal) diet and basal diets supplemented with 0.2 and 2.0 ppm selenium as sodium selenite were injected intraperitonially with(75)Se as sodium selenite (2.8 microcuries). The injected(75)Se was monitored in blood, liver, kidney, heart, and testis at 24, 72, and 144 h after injection. Maximal uptake of the injected(75)Se was observed in tissues of quails maintained on basal diet. The uptake of(75)Se in tissues in general was determined by the dietary Se status. Among the organs studied, kidney had the maximal level of(75)Se, 0.2 ppm (μg/g wet tissue) followed by liver, testis, and heart, but testis had the maximal level when the level per milligram of protein was considered, about 3.0 ng/mg protein, followed by liver, kidney, and heart. About 10-20% of the tissue(75)Se was located in the mitochondria and 50-60% in the post-mitochondrial supernatant fractions in all dietary Se levels. Significant incorporation of(75)Se in the mitochondrial membrane was observed. The percent distribution ratio between the membrane and matrix fractions of the mitochondria remained constant at all dietary Se levels which, in liver was 65∶35, in kidney 55∶45, and in testis 75∶25. However, in heart mitochondria, the distribution of(75)Se between membrane and matrix varied with dietary Se status, the ratio being 82∶18 in the basal group, and 72∶28 and 41∶59 in the 0.2 and 2.0 ppm Se-supplemented groups, respectively. This is indicative of a preferential uptake of(75)Se in the mitochondrial membrane in conditions of deficiency. About 40-60% of the mitochondrial membrane-associated(75)Se was released upon Triton treatment in all the organs. Of the membrane-bound(75)Se, about 10-15% was acid-labile in liver and kidney and 25% in the heart tissue. Possibilities of tissue specific roles, especially in the heart mitochondrial membrane-related processes, are indicated for selenium.
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TL;DR: Electron microscopic observations revealed structural changes such as loss of cristae with proliferative and degenerative changes of the mitochondria in Se deficiency and involvement of Se in maintaining structure and functional efficiency of mitochondria is evident from the present study.
Abstract: Selenium (Se) deficiency in the experimental models, Coturnix coturnix japonica and Corcyra cephalonica, resulted in impaired mitochondrial substrate oxidations and lowered thiol levels. Studies with respiratory inhibitors confirmed reduced mitochondrial electron transport enzyme activities, especially at cytochrome c oxidase (COX), the terminal segment. Enhanced mitochondrial lipid peroxidation in Se deficiency was more pronounced in the heart tissue of the quail compared to other tissues. Glutathione peroxidase (GSH-Px) activity toward H2O2 and cumene hydroperoxide were generally low in the insect muscle tissue and activity toward H2O2 was maximal in the quail heart mitochondria that was not very sensitive to Se status. Lowered COX activity in Se deficiency was more directly correlated with the increased level of lipid peroxidation than with the GSH-Px activity measured, suggestive of Se mediated protective mechanisms independent of GSH-Px. Electron microscopic observations revealed structural changes such as loss of cristae with proliferative and degenerative changes of the mitochondria in Se deficiency. Involvement of Se in maintaining structure and functional efficiency of mitochondria is evident from the present study.
35 citations
TL;DR: The results including the differential response of GR activity to Se or mimosine supplementation are reflective of an effective reductive environment in Se groups and increased turnover of GSH in the presence of Mimosine.
Abstract: Actaptive alterations in glutathione (GSH) metabolism were studied during oxidative stress induced by selenium (Se) deficiency in germinating seedlings ofTrigonella foenum- graecum grown for 72 h and the response to supplementation individually of Se or mimosine was explored. Growth enhancement with improved mitochondrial efficiency was elicited by supplementation of Se at 0.5-0.75 ppm or mimosine at 0.1-0.2 mM. Total thiol and protein levels of mitochondrial and soluble fractions, in general, did not vary significantly with supplementation of either Se or mimosine except that the mitochondrial protein levels in mimosine groups (0.1-0.2 mM) decreased by 20–30%. Mitochondrial glutathione peroxidase (GSH-Px) increased by twofold in activity toward H2O2, cumene hydroperoxide (CHP), and t-butyl hydroperoxide (tBHP) in Se groups, and by 50–60% increase toward H2O2 and CHP but by a twofold enhancement in enzyme activity with tBHP in mimosine groups. Soluble GSH-Px activity increased by 30–40% only in mimosine groups and remained unaltered in Se groups. Glutathione S-transferase activity (GST) in the soluble fraction of both Se and mimosine groups increased dramatically by fivefold to sixfold. Distinct differences were noted in the response of the stressed seedlings toward exposure to Se or mimosine and included a decline in glutathione reductase (GR) activity by 50–60% in both mitochondria and soluble fractions of Se groups and an increase in GR activity of the mitochondria by twofold and of the soluble enzyme activity by 30% in the mimosine groups. Mimosine exposure resulted in a dose-dependent decrease in the γ-glutamyl transpeptidase levels, but, in contrast, a significant enhancement by 50% was noted in the Se group at 0.75 ppm. The results including the differential response of GR activity to Se or mimosine supplementation are reflective of an effective reductive environment in Se groups and increased turnover of GSH in the presence of mimosine.
23 citations
Cites background from "Selenium-mediated biochemical chang..."
...The severe symptoms of oxidative stress prevalent in Se deficiency, well studied in animal systems (13-15), are coincidental with altered glutathione metabolism, including elevation of glutathione S-transferase (GST), a nonselenoenzyme, involved in detoxication mechanisms....
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TL;DR: It is demonstrated for the first time that mimosine, a naturally occuring toxic amino acid, could be a beneficial growth factor in concentrations between 0.1 and 0.2 mM.
Abstract: Oxidative stress during selenium (Se) deficiency in the seedlings ofTrigonella foenum-graecum grown for 72 h was investigated and the response to supplemented levels of Se (0.5-1 ppm) and mimosine (0.05-1 mM) was evaluated. Beneficial effects of Se was maximal at 0.75 ppm. Mimosine, a toxic amino acid, was also found to be beneficial to the growth of the seedlings exposed up to 0.2 mM. When compared to the stressed seedlings, mitochondrial oxygen uptake from seedlings of Se (0.75 ppm) group and mimosine (0.2 mM) group exhibited threefold enhancement in state 3 respiration rate and a controlled state 4 rate, with respiratory control ratios of 5–8. Upon supplementation at the optimal levels, Superoxide dismutase (SOD) activities were enhanced fourfold with Se and eightfold with mimosine in the mitochondria. The soluble activity in mimosine groups increased twofold, but only by 75% in Se groups. Peroxidase activity registered a significant increase by threefold in mitochondria and fourfold in soluble fraction in both Se and mimosine groups. Exposure to Se or mimosine exhibited a differential response in the mitochondrial catalase and ascorbate peroxidase (Asc-Px) activities. In the Se groups, both catalase and Asc-Px in mitochondria decreased by 50–60%, which was contrasted by 60% increase in Asc-Px activity and 40% in catalase activity in mimosine groups. Supplementation with either Se or mimosine evoked similar responses of increases with respect to soluble catalase by twofold to threefold and Asc-Px by 90%. The results of the present study reveal (1) the Prevalence of oxidative stress inT. foenum-graecum during Se deficiency, (2) enhanced mitochondrial functional efficiency mediated by Se and mimosine independently, and (3) an antitoxidative role for mimosine during Se deficiency. The study demonstrates for the first time that mimosine, a naturally occuring toxic amino acid, could be a beneficial growth factor in concentrations between 0.1 and 0.2 mM.
19 citations
Cites background from "Selenium-mediated biochemical chang..."
...Experimental Se deficiency in animals has been widely studied (14-17), which indicates reversible and specific Se-dependent enzyme modulation in a variety of species....
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TL;DR: In this article, the requirement, uptake, and subcellular distribution of Na2 · 75SeO3 in the larvae of C. cephalonica was investigated, and a more fundamental role for selenoprotein in the mitochondrial energy metabolism emerges from these studies.
Abstract: Requirement, uptake, and subcellular distribution of Na2
75SeO3 in the larvae of the insectC. cephalonica was investigated. That Se is well tolerated byC. cephalonica upto an added level of 2 ppm in the diet is suggested by the observed increase in body weight, total protein, and succinate dehydrogenase levels. Significant increases in the State 3 respiration ensued with Se supplementation up to 2 ppm in the mitochondrial oxidation of D-glycerol 1-phosphate, succinate and NADH, along with concomitant unaltered State 4 respiration, leading to enhanced RCR values. Maximal uptake of75Se was registered in the larvae maintained on basal diet when subjected to short-term exposure to 0.5 ppm75Se level. When exposure level was further increased up to 20 ppm, the observed decrease in the uptake of75Se suggested that Se status of larvae itself controlled the tissue uptake. Subcellular distribution pattern revealed maximal incorporation of75Se (cpm/g tissue) in the supernatant fraction, whereas, maximal specific75Se activity (cpm/mg protein) was associated with the mitochondrial fraction. Autoradiography of the soluble fractions indicated the presence of single selenoprotein in the larval group with short term 2 ppm75Se exposure. Inherent Se controls both the extent and the nature of distribution of mitochondrial75Se incorporation. Uptake of45Ca by the insect mitochondria was enhanced by dietary Se up to 2 ppm but was unaffected by addition ofin vitro
75Se in the medium. A more fundamental role for Se in the mitochondrial energy metabolism emerges from these studies.
16 citations
TL;DR: The study reveals a differential response to Se among the β-galactosidase and β-glucosid enzyme of T. foenumgraecum with increase in the levels of β-GalactOSidase activity.
Abstract: Beta-glucosidase and beta-galactosidase activity profile tested in different seeds during 24 h germination revealed reasonably high levels of activity in Vigna radiata, Cicer arietinum, and Trigonella foenum-graecum. In all seeds tested, beta-galactosidase activity was, in general, higher than that of beta-glucosidase. T. foenum-graecum seedlings exhibited maximal total and specific activities for both the enzymes during 72 h germination. Se supplementation as Na2SeO3 up to 0.75 ppm was found to be beneficial to growth and revealed selective enhancement of beta-galactosidase activity by 40% at 0.5 ppm Se. The activities of both the enzymes drastically decreased at 1.0 ppm level of Se supplementation. On the contrary, addition of Na2SeO3 in vitro up to 1 ppm to the enzyme extracts did not influence these activities. Hydrolytic rates of beta-glucosidase in both control and Se-supplemented groups were enhanced by 20% with 0.05 M glycerol in the medium and 30% at 0.1 M glycerol. The rates were marginally higher in Se-supplemented seedlings than the controls, irrespective of added glycerol in the medium. In contrast, hydrolysis by beta-galactosidase showed a trend of decrease in Se-supplemented seedlings compared to the control, when glycerol was present in the medium. Addition of Se in vitro in the assay medium showed no difference in the hydrolytic rate by beta-galactosidase when compared to control, while the activity of beta-glucosidase declined by 50%. Se-grown seedlings showed an enhancement of transglucosidation rate by 40% in the presence of 0.1 M glycerol. The study reveals a differential response to Se among the beta-galactosidase and beta-glucosidase of T. foenum-graecum with increase in the levels of beta-galactosidase activity.
6 citations
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TL;DR: It is suggested, in the light of these and other observations, that the selenide may form a part of the active centre of a non-haem iron-containing protein ;X', that may function in microsomal electron transport.
Abstract: 1. The incorporation of (75)Se from Na(2) (75)SeO(3) into the liver endoplasmic reticulum of rats given phenobarbitone was investigated by using a zonal centrifuge technique. 2. It was found that, in rats deprived of vitamin E, or of vitamin E and selenium, phenobarbitone was without effect on the incorporation of (75)Se or on its conversion to (75)Se(2-). When vitamin E was given at the same time as the phenobarbitone and (75)Se, there was a large increase in the amount of (75)Se and (75)Se(2-) found in the smooth reticulum. It is concluded that there may be a specific vitamin E-dependent role for selenium and selenide in the smooth endoplasmic reticulum, and it is suggested, in the light of these and other observations, that the selenide may form a part of the active centre of a non-haem iron-containing protein ;X', that may function in microsomal electron transport. 3. Measurements of the contents of cytochromes P-450 and b(5) in liver microsomal fractions of rats given vitamin E-deficient, and vitamin E- and selenium-deficient diets, showed that haemoprotein biosynthesis is unimpaired in these rats and phenobarbitone treatment resulted in the expected increase in the haemoproteins. 4. When the reduction of cytochrome P-450 by NADH and NADPH was measured, no difference was found between normal and deficient animals. 5. These results are discussed in relation to current knowledge of microsomal electron transfer.
28 citations
TL;DR: To investigate the effect of selenium in relation to different environmental conditions a study on the kinetics of the element in mice has been carried out on 54 female mice, finding a biphasic elimination.
Abstract: To investigate the effect of selenium in relation to different environmental conditions a study on the kinetics of the element in mice has been carried out on 54 female mice. 75Se (selenite) was administered as a single dose or continuously through drinking water. Different dosage levels were used ranging from "tracer dose" to subtoxic doses. Wholebody counts revealed a biphasic elimination. The first rapid phase was strongly dose-dependent, while the slower second phase of elimination appeared independent of dose as well as mode of administration with a biological half-life of 14.4 +/- 3.2 days. Liver, blood, kidney and lungs were found to contain most of the selenium, here also a two-phased elimination was observed. The biological half-lives for elimination calculated during the second phase gave a mean of 10.7 days with a range of 8.7 to 12.5 days. With continuous administration through drinking water a steady state was obtained after 300 to 400 hours of administration according to concentration. A linearity between amount retained at steady state and log concentration in drinking water is indicated. The results on biological half-lives are discussed in relation to previous publications.
19 citations
TL;DR: It was found that the detection of non-haem iron in microsomes from normal rats was dependent upon the presence of antioxidants in the media used for the subcellular fractionation and subsequent measurement of the non- haem iron.
Abstract: Diplock et al. [l] showed that a significant proportion of the 75Se in a dose of Na275Se03 given to rats was converted to an acid-labile form found in liver subcellular organelles, which has been identified (Diplock et al. [2] ) as selenide. The selenide is particularly associated with mitochondria and smooth endoplasmic reticulum, is protein-bound, and its presence is dependent on the presence of vitamin E in the animal’s diet (Caygill et al. [3] ). It has been suggested that a function of vitamin E is to protect the selenide from oxidation in vivo, and that the selenide may form part of the active centre of a class of non-haem iron proteins (Diplock and Lucy [4] ). In this paper, results are presented in which the presence of non-haem iron in rat liver microsomes was investigated using an established technique; the influence of the addition of antioxidants in vitro, and the presence or absence of dietary vitamin E and selenium, were also examined. It was found that the detection of non-haem iron in microsomes from normal rats was dependent upon the presence of antioxidants in the media used for the subcellular fractionation and subsequent measurement of the non-haem iron. When vitamin E was removed from the diet of the animals, the oxidant-sensitive non-haem iron was replaced by a form of non-haem iron that was not readily oxidisable.
12 citations
TL;DR: The differential response of mitochondrial and soluble GSH-Px activities to Se and other related observations on mitochondrial functions suggest an additional role for Se in mitochondrial membrane processes and glutathione-related metabolic regulations.
Abstract: Essentiality of selenium (Se) for Japanese quail,Coturnix coturnix japonica, was confirmed using a formulated semipurified low-Se diet (basal) (0.05 ppm). Selenium-deficiency symptoms appeared in quails on this diet within 15 d, which corresponded to low levels of hemolysate glutathione peroxidase (GSH-Px) activity. Selenium administration at 0.05 and 2.0 ppm levels resulted in an increase of hemolysate GSH-Px activity by 64 and 116%, respectively, in both short- and long-term experiments. Growth over a 2-mo period increased the hemolysate GSH-Px activity by 120% at each level of dietary Se. A differential response was exhibited by hepatic mitochondrial and soluble GSH-Px activity to Se supplementation, the former increasing progressively with increments of Se at 0.05, 2.0, and 4.0 ppm by 45, 70 and 150%, respectively. The soluble GSH-Px activities of tissues, such as liver, kidney, and testis, and RBC membrane-bound activity remained unchanged in long-term studies at different levels of Se. Replenishment of Se to quails maintained on low-Se diets reflected no change in RBC membrane-bound and liver-soluble GSH-Px activities, although the activity in hemolysate increased consistently with Se. The GSH-Px activity in hemolysate was restored to the levels comparable to those of long-term studies only at Se administration at the 2.0-ppm level. The differential response of mitochondrial and soluble GSH-Px activities to Se and other related observations on mitochondrial functions suggest an additional role for Se in mitochondrial membrane processes and glutathione-related metabolic regulations.
8 citations
TL;DR: The increase in skin GSH-Px activity and concurrent increase in polymeric collagen on increasing the dietary Se level suggest a possible role for Se in collagen metabolism.
Abstract: The effect of selenium (Se) on collagen characteristics and glutathione peroxidase (GSH-Px) activity in the skin of Japanese quailsCoturnix coturnix japonica fed a formulated, semipurified, low-Se diet (basal) (0.05 ppm) was investigated. The quails exhibited severe Se-deficiency symptoms and significant reduction in skin GSH-Px activity at the end of 30 d. Selenium supplementation at a 2-ppm level restored the normal skin conditions and enhanced skin GSH-Px activity significantly. But a dietary Se level of 0.1 ppm was found to be inadequate in restoring the general skin conditions and GSH-Px activity. A markedly low total collagen content of about 23% was observed in the skin of quails fed the basal diet, compared to 39% of total collagen content in the skin of the 2-ppm Se-supplemented group. Molecular organization of skin collagen of quails on the basal and 0.1-ppm Se diet showed an abundance of monomeric forms with less crosslinks, compared to the presence of polymeric forms with more crosslinks, indicating enhanced stability in the skin collagen of quails on the 2-ppm diet. The delay in the in vitro fibril formation of collagen from the basal and 0.1-ppm Se groups, compared to a relatively faster rate in the case of the 2-ppm Se group, indicates a disturbance in the aggregation phenomenon of collagen. The increase in skin GSH-Px activity and concurrent increase in polymeric collagen on increasing the dietary Se level suggest a possible role for Se in collagen metabolism.
5 citations