Effect and possible role of Zn treatment in LEC rats,an animal model of Wilson's disease

The effect of oral zinc (Zn) treatment was studied in the liver, kidneys and intestine of Long-Evans Cinnamon (LEC) rats in relation to metals interaction and concentration of metallothionein (MT) and glutathione (GSH). We also investigated the change in the activity of antioxidant enzymes and determined the biochemical profile in the blood and metal levels in urine. We showed that the Zn-treated group had higher levels of MT in the hepatic and intestinal cells compared to both untreated and basal groups. Tissue Zn concentrations were significantly higher in the Zn-treated group compared to those untreated and basal, whereas Cu and Fe concentrations decreased. The antioxidant enzyme activities in the Zn-treated group did not change significantly with respect to those in the basal group, except for hepatic glutathione peroxidase activity. Moreover, the biochemical data in the blood of Zn-treated group clearly ascertain no liver damage. These observations suggest an important role for Zn in relation not only to its ability to compete with other metals at the level of absorption in the gastrointestinal tract producing a decrease in the hepatic and renal Cu and Fe deposits, but also to MT induction as free radical scavenger.     

Influence of maternal mineral deficiency on the hepatic metallothionein and zinc in newborn rats

The effects of maternal Zn, Cu, or Fe deficiencies during late gestation on hepatic levels of metals and metallothionein (MT) and the binding of Zn and Cu to protein fractions were investigated in newborn rats. Timed pregnant rats were fed one of the following diets: Zn deficient (Zn-D), Cu-D, Fe-D, or control from day 12 of gestation until birth. The specific nutritional deficiency status of the dams was confirmed by low plasma levels of the deficient metal. Livers from pups were analyzed for MT, metal content, and metal-protein binding. Maternal Zn-D resulted in a greater than 50% reduction of hepatic MT levels in pups, whereas Cu-D and Fe-D had no significant effects. Pups in each deficient group showed a significant decrease in the hepatic levels of the respective metals. Fractionation of hepatic cytosols from the pups by Sephadex G-75 gel filtration showed that in both Fe-D and Cu-D pups the respective metals were depleted from the high molecular weight protein fraction, whereas in Zn-D pups the Zn was depleted mainly from the MT fraction (Ve/V0 approximately 2). Incorporation of [35S] cysteine into MT fractions was significantly lower in Zn-D pups as compared with control pups. These results indicate that there is a specific effect of the maternal Zn-D on the hepatic storage of Zn as MT in newborn rats.     

Effect and possible role of Zn treatment in LEC rats,an animal model of Wilson's disease

The effect of oral zinc (Zn) treatment was studied in the liver, kidneys and intestine of Long–Evans Cinnamon (LEC) rats in relation to metals interaction and concentration of metallothionein (MT) and glutathione (GSH). We also investigated the change in the activity of antioxidant enzymes and determined the biochemical profile in the blood and metal levels in urine. We showed that the Zn-treated group had higher levels of MT in the hepatic and intestinal cells compared to both untreated and basal groups. Tissue Zn concentrations were significantly higher in the Zn-treated group compared to those untreated and basal, whereas Cu and Fe concentrations decreased. The antioxidant enzyme activities in the Zn-treated group did not change significantly with respect to those in the basal group, except for hepatic glutathione peroxidase activity. Moreover, the biochemical data in the blood of Zn-treated group clearly ascertain no liver damage. These observations suggest an important role for Zn in relation not only to its ability to compete with other metals at the level of absorption in the gastrointestinal tract producing a decrease in the hepatic and renal Cu and Fe deposits, but also to MT induction as free radical scavenger.     

Effects of Chronic Cadmium Poisoning on Zn, Cu, Fe, Ca, and Metallothionein in Liver and Kidney of Rats

An experiment was conducted to invest effects of chronic cadmium poisoning on Zn, Cu, Fe, Ca, and metallothionein gene expression and protein synthesis in liver and kidney in rats. Forty rats, 6?weeks old, were randomly allocated into two groups. A group was given CdCl(2) (1?mg/KgCd(2+)) by intraperitoneal injection once a day. The other group was treated with normal saline in the same way. Liver and kidney were collected for analysis at the end of the third week. Results showed that Cd exposure increased Cd (P?相似文献   

Early effects of surgery on zinc and metallothionein levels in female rats

Time-response effects of experimental surgery on zinc (Zn) and metallothionein (MT) homeostasis were investigated in female rats up to 24 h. Hepatic Zn content increased at 20 and 24 h postsurgery, whereas serum Zn levels decreased. Hepatic MT increased significantly by 9 h postsurgery and peaked at up to twofold of control at 12 h after surgery. Following the peak at 12 h, hepatic MT content decreased with time but did not reach control levels at the end of this study. When MT isoforms were evaluated, MT-II levels were elevated to the highest extent by 12 h after surgery, whereas MT-I levels started to decrease after 3 h postsurgery but then increased by 20 h. The early increases in MT content are probably mediated by nonmetallic mediators released during the postsurgical inflammatory process, favoring the plasma/tissue mobilization of Zn. This process might be part of the overall mechanisms occurring in the inflammation.     

Elevation of hepatic levels of metallothionein and zinc in mice bearing experimental tumors.

A tumor growth-dependent elevation in the hepatic levels of Zn and metallothionein (MT), without a change in the level of Cu, was found in mice and rats bearing solid tumors in the inguinal region. The levels of Zn and MT thus elevated gave a significant correlation (r = 0.95) between them. Nevertheless, when tumor-bearing mice and rats were fed a Zn-deficient diet, the hepatic levels of Zn and MT did not increase. In mice in which inflammation was induced at the same region, on the other hand, hepatic levels of Zn and MT increased transiently after the injection of turpentine or carrageenan even when they were fed the Zn-deficient diet. These results suggest that the elevation of MT and Zn levels can be a helpful marker for detecting malignancy.     

Effect of gamma irradiation on liver metallothionein synthesis and lipid peroxidation in rats.

Several studies have recently shown that metallothionein (MT), a protein characterized by a high thiol content and that binds Zn2+ and Cu+, might be involved in the protection against oxidative stress and can act as a free radical scavenger. Oxidative stresses, such as irradiation, increase lipid peroxidation (LP) and subsequent tissue damage through free radical production. The induction of hepatic MT synthesis by gamma-irradiation (20 Gy) at 8, 24, 30 and 48 hrs. post-irradiation in two different age groups of Sprague-Dawley rats (39-40 and 48-49 days old) was studied. LP measured by the thiobarbituric acid reactive substances (TBARS) assay and Cu and Zn levels in liver have also been determined. In the younger group, the gamma-irradiation induced hepatic MT synthesis and increased LP that peaked 24 hrs. after irradiation. During the first 30 hrs. post-irradiation, a positive and statistically significant correlation between hepatic MT content and LP level in liver was found. In the older group, liver MT synthesis was only increased 1.7-fold and LP levels were not altered at 24 hrs. post-irradiation compared with sham-irradiated rats.Therefore it appears that LP is not necessary for induction of MT synthesis by gamma-irradiation.     

Effects of repetitive immunogen injections and fasting versus feeding on iron,zinc, and copper metabolism in chicks

Most investigations on the effect of immunogenic challenge on trace-mineral metabolism use a single immunogen injection in fasted animals. Because these investigations are not representative of realistic situations in which animals are constantly exposed to immunogens and still consume feed, the following studies were done. In Expt. 1, chicks were injected ip with sheep red blood cells (SRBC), Sephadex, SRBC+Sephadex, or saline. Chicks were then fasted or fed equal amounts of feed (equal fed) for 16 h. Immunogen injection decreased serum Fe and Zn and increased serum Cu within each feeding program. Differences in Cu, and to a lesser extent Zn, concentrations between immunogen- and saline-injected chicks were more pronounced in fasted than in equal-fed chicks. In Expt. 2, equalfed chicks were injected ip every 48 h for 6 d with SRBC+Sephadex or saline. Two days after each injection, tissues were taken. An additional group of chicks was injected once and subsequently fasted 16 h, whereupon tissues were taken. Changes in plasma Fe, Zn, Cu, and ceruloplasmin; hepatic Fe, Zn, Cu, and metallothionein; pancreatic Fe and Zn; and splenic Fe in repetitively injected chicks were different from changes observed in chicks injected once. The results indicate that the trace-mineral response to immunogenic challenge is dependent upon the number of immunogen injections and the nutritional state of the animal.     

Hepatic,placental, and fetal trace elements following molybdenum supplementation during gestation

The effect of dietary Mo (Na2Mo(4)2H2O) added to drinking water at levels of 0, 5, 10, 50, or 100 mg on hepatic (gestating dams), placental, and fetal Mo, Cu, Zn, and Fe contents of Sprague-Dawley rats was studied. These elements were determined by a polarographic catalytic procedure for Mo and by atomic absorption spectrophotometry for Cu, Fe, and Zn. Hepatic Mo increased two to sixfold (5-100 mg Mo). There was a 1.5-fold increase in hepatic Cu, significant only at the 50 to 100 mg Mo/L treatment levels. Although the hepatic Fe content of the gestating rats significantly increased with Mo supplementation, the extent of the increase appeared to be influenced by the litter size, fetal weights, and the degree of fetal resorption. Zinc values did not differ at any of the treatment levels. Placental Mo increased 3-76-fold, Cu one to threefold. No differences were observed in placenta Fe or Zn. Fetal Mo increased two to six-fold (10-100 mg/L) and Cu increased one to fivefold. There were no differences in the Fe and Zn content although both of these elements appeared to decline as the level of supplemental Mo increased. Significant correlations were also observed between hepatic, placental, and fetal Mo, Cu, Fe, and Zn. These results suggest that changes in trace mineral status in gestation, owing to high Mo intake, do occur and such occurrences are also reflected in the fetus.     

Interactions between Zn and Cu in LEC rats, an animal model of Wilson's disease

The effect of oral Zn treatment was studied in the liver and kidneys of 26 male Long-Evans Cinnamon (LEC) rats (mutant animals, 5 weeks old) in relation to both the interaction between Zn and Cu and the localisation and concentration of metallothionein (MT). Rats receiving 80 mg zinc acetate daily by gavage and control rats receiving no treatment were killed after 1 or 2 weeks. By immunohistochemical and analytical chemical techniques we revealed that treated rats had higher levels of MT in the hepatic and renal cells compared to untreated ones. Tissue Zn concentrations were significantly higher in treated rats compared to untreated whereas Cu concentrations decreased in the liver and kidneys as indicated by analytical chemical analyses. MT levels also decreased with treatment period. A histochemical procedure, obtained using autofluorescence of Cu-metallothioneins, confirms these findings: after 2 weeks, the signal decreased in both the liver and kidney sections. This gives a greater understanding of the mechanism of Cu metabolism in the two tissues considered. These results suggest that Zn acts both to compete for absorption on the luminal side of the intestinal epithelium and to induce the synthesis of MT.     

Zinc supplementation decreases hepatic copper accumulation in LEC rat

The effect of dietary zinc (Zn) supplementation on copper (Cu)-induced liver damage was investigated in Long-Evans Cinnamon rats (LEC), a model for Wilson's disease (WD). Four-week-old LEC (N=64) and control Long-Evans (LE) (N=32) female rats were divided into two groups; one group was fed with a Zn-supplemented diet (group I) and the other was given a normal rodent diet (group II). LEC rats were killed at 6, 8, 10, 12, 18, and 20 wk of age; the LE control rats were killed at 6, 12, 18, and 20 wk of age. Cu concentration in the liver was reduced in LEC rats fed the Zn-supplemented diet compared with LEC rats on the normal diet between 6 and 18 wk of age. Metallothionein (MT) concentration in the livers of LEC rats in group I increased between 12 and 20 wk of age, whereas hepatic MT concentration in LEC rats from group II decreased after 12 wk. Hepatocyte apoptosis, as determined by TUNEL, was reduced in Zn-supplemented LEC rats at all ages. Cholangiocellular carcinoma was observed only in LEC rats in group II at wk 20. These results suggest that Zn supplementation can reduce hepatic Cu concentration and delay the onset of clinical and pathological changes of Cu toxicity in LEC rats. Although the actual mechanism of protection is unknown, it could be explained by sequestration of dietary Cu by intestinal MT, induced by high dietary Zn content.     

Interaction of metallothionein and carbon tetrachloride on the protective effect of zinc on hepatotoxicity

To study the influence of hepatic metallothionein (MT) on the hepatotoxic response to carbon tetrachloride (CCl4), adult male rats were pretreated with a 10 mg X kg-1 dose of zinc (Zn) 24 h prior to CCl4 (i.p., l mL X kg-1) treatment. Zn pretreatment increased the hepatic MT concentrations markedly and reduced the magnitudes of the CCl4-induced reduction of cytochrome P450 concentration as well as elevation of serum alanine aminotransferase and aspartate aminotransferase activities when determined at 4 or 24 h following CCl4 treatment. Treatment of Zn-exposed animals with CCl4 also resulted in significant reduction of the concentrations of hepatic MT (as determined by the cadmium-saturation method) as well as cytosolic Zn. Sephadex G-75 chromatographic study of hepatic cytosols showed that MT-bound Zn was selectively depleted by CCl4 exposure. Moreover, it was demonstrated that CCl4, after metabolic activation, reduced the cadmium binding capacity of Zn-induced hepatic MT in vitro. To examine the possible protective effect of Zn independent of induction of MT synthesis, CCl4 was administered 2 h following Zn pretreatment and the hepatotoxic response was examined 4 h later. This study revealed limited protection by Zn prior to the induction of MT synthesis. These data further support a role of MT in the modulation of CCl4 hepatotoxicity.     

Associations among prostaglandin F2alpha, plasma zinc, copper and iron concentrations and fetal loss in cows and mares

The objective of this study was to test the hypothesis that PGF2alpha is associated with abortion and changes in plasma Zn, Cu, and Fe concentrations in cows and mares in their first trimester of pregnancy. Eleven pregnant cows were infused with endotoxin (n = 5) or endotoxin plus an inhibitor of cycloxygenase, flunixin meglumine (n = 6). Blood was collected over a 5-d period. Additionally, 4 mares were treated every 24 h with cloprostenol sodium and blood was collected hourly until abortion. Plasma Zn, Cu, and Fe were determined. Three of five cows treated with endotoxin aborted, but none of the six cows treated with endotoxin and flunixin meglumine aborted. Aborting cows had lower plasma Zn (P = 0.048) over the 5-d study period compared with the nonaborting cows. The changes in Zn corresponded to release of PGF2alpha. All 4 mares aborted and plasma Zn concentrations were lower (P = 0.008) and Cu/Zn was higher (P = 0.02) 12 h after cloprostenol treatment. Plasma Zn may be a useful biomarker for risk of spontaneous abortion, and the decline in plasma Zn may be caused by PGF2alpha.     

Effects of three chelating agents,EDTA, NTA,and TPP,on the concentration of elements in rat tissues

Ethylene diamine tetraacetic acid (EDTA), nitrilotriacetic acid (NTA), and tripolyphosphate (TPP) sodium salts were given orally to rats at the dose of 1 mmol/kg/d for 35 d. The concentrations of Na, K, Ca, Mg, P, S, Fe, Sr, Cu, and Zn were determined in blood, plasma, brain, heart, muscle, liver, kidney, duodenum, and bone of control rats and of the rats receiving EDTA, NTA, and TPP. The main effect induced by EDTA, NTA, and TPP was a decrease of the concentrations of several elements Ca, Mg, Fe, P in the duodenum. Otherwise, EDTA induced an increase of Zn in the kidney (+ 20%), NTA, an increase of Fe in liver (+ 29%), and particularly an increase of Zn in bone (+ 44%). TPP induced a slight decrease of Zn and Cu in liver. In conclusion, EDTA, NTA, and TPP taken orally at the dose of 1 mmol/kg/d for 35 d induced moderate changes of the concentrations of some elements in rat tissues, but without signs of toxicity.     

Effects of dexamethasone on metallothionein induction by Zn, Cu, and Cd in Chang liver cells

Metallothioneins (MTs) were induced in Chang liver cells by the metals, Zn, Cu and Cd, and the glucocorticoid hormone, dexamethasone. When 116 microM Zn, 32 microM Cu and 18 microM Cd, and 10(-7) M dexamethasone, respectively, were administered for 9 h, MTs induced by each inducer in the cells reached maximum levels. The maximum accumulation of MT level induced by dexamethasone was the lowest of the four inducers investigated; the levels induced by Zn, Cu and Cd were 4.7, 1.2 and 1.5 times of that induced by dexamethasone. When dexamethasone was added to the cells together with the heavy metals (Zn, Cu and Cd), dexamethasone had an additive effect on the maximum MT accumulations induced by heavy metals as compared to when induction was conducted using one of heavy metals alone or by dexamethasone alone. However, dexamethasone did almost not effect the metal accumulations in the cells, although the maximum MT levels induced by heavy metal increased by dexamethasone. These results suggest that the process of MT induction by heavy metals and that by dexamethasone are independent of one another. When dexamethasone was added to the cells together with a high concentration of Cu (32 microM) induced the maximum MT accumulation, Cu transport into the cells decreased by 20-40% of that into non-treated cells, which was statistically significant.     

Effect of Zn treatment on wild type and MT-null cell lines in relation to apoptotic and/or necrotic processes and on MT isoform gene expression

It has been shown in various systems that zinc is able to antagonize the catalytic properties of the redox-active transition metals iron and copper, although the process is still unclear. Probably, the protective effect of Zn against oxidative stress is mainly due to the induction of a scavenger metal binding protein such as metallothionein (MT), rather than a direct action. To support this hypothesis, in this study, the effects of Zn, Cu, Fe, Zn + Cu and Zn + Fe treatments were investigated in a fibroblast cell line corresponding to an SV40-transformed MT-1/-2 mutant (MT-/-), and in wild type (MT+/+), by valuing metal concentrations and apoptotic and/or necrotic processes. We also investigated the synthesis of MT and the levels of both MT-1 and MT-2 mRNAs. In MT+/+ cells, co-treatment with Zn + Fe caused a decrease in Fe content compared to treatment with Fe alone. After Zn and Zn + Cu exposure the expression of MT-1 and MT-2 isoforms increased with a concomitant increase in MT synthesis. Annexin V-FITC and propidium iodide staining revealed necrotic or apoptotic cells in terminal stages, especially after Fe treatments. Immunofluorescent staining with an anti-ssDNA Mab and annexin detected a lower signal in co-treated cells compared to the single treatments in both cell lines. The intensity and quantity of fluorescence resulting from anti-ssDNA and Annexin V staining of MT null cells was higher compared to wild type cells. These results suggest that Zn alone does not completely exert an anti-oxidant effect against Cu and Fe toxicity, but that induction of MT is necessary.     

Effects of different proteins on the metabolism of Zn, Cu, Fe, and Mn in rats

Many factors are known to influence trace element metabolism and one of them is dietary protein. The present study examines the effects of casein, soybean protein, and peanut protein on the metabolism of the Zn, Cu, Fe, and Mn in growing rats. The results showed that Zn, Fe, and Mn excretions in the feces of peanut protein-fed rats (PPERs) were similar to that of casein-fed rats (CPFRs) (p>0.05), whereas all of the Zn, Cu, Fe, and Mn excretions in the urine of PPFRs were significantly higher than that of CPFRs (p<0.05), but its apparent absorption rate (AAR) of Cu, Fe and its apparent retention rate (ARR) of Cu were all higher than that of CPFRs (p<0.05). Hepatic Zn content of soybean protein-fed rats (SPFRs) was higher than that of CPFRs and PPFRs (p<0.05 respectively) and serum, renal, and femoral Cu contents of SPFRs were significantly lower; however, hepatic Cu, and renal Mn contents were significantly higher than that of CPFRs (p<0.05, respectively); The hepatic Fe content of SPFRs was significantly higher than that of CPFRs and PPFRs (p<0.01, respectively). To sum up, compared to casein, soybean protein might be a good dietary source to make up for Zn and Fe deficiency, and also peanut protein to make up for Cu and Fe deficiency.     

Iron,copper, and zinc status in rats fed supplemental nickel

Literature data concerning the effect of increasing dietary Ni concentrations on Fe, Cu, and Zn status in rats are sparse and, in part, controversial. Therefore, the effects of the addition of either 0, 3, 50, or 100 mg Ni/kg diet on Fe, Cu, and Zn status of rats were investigated in two separate experiments. Purified diets were used that were composed according to the established nutrient requirements of rats. Ni in kidney was increased with increasing Ni intakes. Dietary Ni did not significantly influence Fe concentrations in plasma, liver, kidney, femur, and spleen. Likewise, the addition of Ni to the diet did not alter Cu status. Zn concentrations in femur were significantly decreased after feeding the diets with 100 mg Ni/kg. However, Zn in plasma, liver, kidney, and spleen was not affected. It is concluded that variations in dietary Ni concentrations have no major impact on Fe, Cu, and Zn status in rats.