Metabolic effects after short-term sublethal cadmium exposure to dogfish (Scyliorhinus canicula)

1. Four groups of dogfish were subjected to 50 ppm of cadmium for 1, 2, 3 and 4 days and haematological and metabolic parameters analyzed from blood and tissue samples.2. A significant increase of blood glucose and lactate was observed.3. No differences were found in the majority of haematological parameters except for the red blood cell counts that showed a significant increase during the second and third day of treatment.4. Comparing liver and muscle metabolism a decrease of protein levels are observed in both tissues and reductions of glycogen in liver and lactate in muscle were detected.5. The results of the different parameters indicate a pattern of dual response depending on the time of exposure; a first phase of toxic impact during the first two days, followed by a second phase of recovery at the end of 4 days treatment.     

Sister-chromatid exchanges induced by triethylenemelamine: in vivo and in vivo/in vitro studies in mouse and Chinese hamster bone marrow and spleen cells

This study was designed to obtain sister-chromatid exchange (SCE) frequencies in bone marrow and spleen cells of mice and Chinese hamsters under in vivo and in vivo/in vitro systems following treatment of animals with varying doses (15-405 micrograms/kg) of triethylenemelamine (TEM). A dose-related SCE response was found in both species, tissues, and systems analyzed following TEM treatment. In vivo, similar responses were noted for both tissues in both species. However, in vivo/in vitro, the response was lower than in vivo and it varied with the tissue. The spleen cells were more sensitive and gave higher numbers of SCEs than bone marrow of both species at the two highest doses tested (135 and 405 micrograms/kg). These differences may be attributed to cell-culturing effects, type of cells analyzed, species and tissue specificities, and pharmacokinetic properties of the chemical. This study lends support to recently established in vivo/in vitro cell culture methodologies employing mice and Chinese hamsters for comparative cytogenetic analysis.     

Displacement of zinc and copper from copper-induced metallothionein by cadmium and by mercury: in vivo and ex vivo studies

The in vitro affinity of metals for metallothionein (MT) is Zn less than Cd less than Cu less than Hg. In a previous study Cd(II) and Hg(II) displaced Zn(II) from rat hepatic Zn7-MT in vivo and ex vivo (Day et al., 1984, Chem. Biol. Interact. 50, 159-174). The ability of Cd(II) or Hg(II) to displace Zn(II) and/or Cu(II) from metallothionein in copper-preinduced rat liver (Zn, Cu-MT) was assessed. Cd(II) and Hg(II) can displace zinc from (Zn, Cu)-MT both in vivo and ex vivo. The in vitro displacement of copper from MT by Hg(II) was not confirmed in vivo and ex vivo. Cd(II) treatment did not alter copper levels in (Zn, Cu)-MT, as expected. Hg(II) treatment, however, did not decrease copper levels in MT, but rather increased them. The sum of the copper increase and mercury incorporation into MT matched the zinc decrease under in vivo conditions and actually exceeded the zinc decrease under ex vivo conditions. Short-term exposure of rat liver to exogenous metals can result in incorporation of these metals into MT by displacement of zinc from pre-existing MT. Displacement of copper from pre-existing MT by mercury, as predicted by in vitro experiments, was not confirmed under the conditions of our in vivo and ex vivo experiments. This result is explainable based on the differing affinities and/or preferences of the two metal clusters in MT.     

A novel approach to the identification and quantitative elemental analysis of amyloid deposits—Insights into the pathology of Alzheimer’s disease

There is considerable interest in the role of metals such as iron, copper, and zinc in amyloid plaque formation in Alzheimer’s disease. However to convincingly establish their presence in plaques in vivo, a sensitive technique is required that is both quantitatively accurate and avoids isolation of plaques or staining/fixing brain tissue, since these processes introduce contaminants and redistribute elements within the tissue. Combining the three ion beam techniques of scanning transmission ion microscopy, Rutherford back scattering spectrometry and particle induced X-ray emission in conjunction with a high energy (MeV) proton microprobe we have imaged plaques in freeze-dried unstained brain sections from CRND-8 mice, and simultaneously quantified iron, copper, and zinc. Our results show increased metal concentrations within the amyloid plaques compared with the surrounding tissue: iron (85 ppm compared with 42 ppm), copper (16 ppm compared to 6 ppm), and zinc (87 ppm compared to 34 ppm).     

Glutamine synthetase isozymes in elasmobranch brain and liver tissues

Glutamine synthetase is present as isozymic forms in the elasmobranchs Squalus acanthias (dogfish shark) and Dasyatis sabina (stingray). Subcellular fractionation of elasmobranch brain and liver tissue shows the enzyme to be predominantly cytosolic in the former tissue and mitochondrial in the latter. For the cytosolic brain enzyme, the subunit Mr equals 42,000 in the stingray and 45,000 in the shark, as determined by sodium dodecyl sulfate-gel electrophoresis/Western blotting. The subunit Mr = 45,000 and 47,000, respectively, for stingray and dogfish mitochondrial liver enzymes. Translation of total brain RNA from both species gives immunoprecipitable nascent peptides of the same size as their respective mature enzymes. However, in liver tissue, translation of glutamine synthetase mRNA yields peptides of higher Mr than that of the mature enzymes. In dogfish liver, Mr = 50,000 for the translation product and, in stingray liver, Mr = 48,000. This suggests that the translocation of the enzyme into liver mitochondria may be via a signal or leader sequence mechanism. The larger liver isozyme of elasmobranch glutamine synthetase is found in kidney where it is also known to be mitochondrial. The smaller cytosolic isozyme occurs in retina, heart, gill, and rectal gland tissue as well as in brain.     

Alterations of mitochondrial protein metabolism in liver, brown adipose tissue and skeletal muscle. During cold-acclimation.

Incorporation of L-[U-14C] leucine into liver, brown adipose tissue and skeletal muscle mitochondrial proteins was determined in vivo and in vitro during cold-acclimation. Major alterations in mitochondrial protein metabolism were observed in brown adipose tissue and skeletal muscle but not in liver. Immediate cold-exposure is accompanied by an inhibition of the in vivo incorporation of L-[U-14C] leucine into mitochondrial proteins of all tissues. However, during cold-acclimation the incorporation of leucine increases markedly in brown adipose tissue, continues to decrease in skeletal muscle, nut does not change appreciably in the liver. Because increased incorporation of L-[U-14C]-leucine into brown adipose tissue mitochondrial proteins was observed both in vivo and in vitro, it can be concluded that the mitochondrial protein-synthesizing system of this tissue is directly affected by the acclimation process. The observed changes in mitochondrial protein metabolism of brown adipose tissue and skeletal muscle might be responsible for the development of several morphological and biochemical alterations that characterize the establishment in these tissues of the cold-acclimated state.     

Effect of a zinc-deficient diet on lipid peroxidation in liver and tumor subcellular membranes

The effect of a zinc-deficient diet on lipid peroxidation in liver and tumor mitochondrial and microsomal membrane preparations from BALB/c mice was investigated. Mitochondrial and microsomal membranes from both tissues displayed increased rates of in vitro peroxidation, both enzymatic and nonenzymatic. Measurement of in vivo peroxidation, using diene conjugation as an index of measurement revealed slight increases in tissues from zinc-deficient animals that were not statistically significant. Serum lipoperoxides analyzed from all three groups revealed no significant differences. The results point to an alteration in the peroxidation potential of mitochondrial and microsomal membranes due to zinc deficiency which may be related to an alteration in fatty acid composition.     

Effect of dietary copper and zinc levels on tissue copper,zinc, and iron in male rats

The interaction between dietary copper and zinc as determined by tissue concentrations of trace elements was investigated in male Sprague-Dawley rats. Animals were fed diets in a factorial design with two levels of copper (0.5, 5 μg/g) and five levels of zinc (1, 4.5, 10, 100, 1000 μg/g) for 42 d. In rats fed the low copper diet, as dietary zinc concentration increased, the level of copper decreased in brain, testis, spleen, heart, liver, and intestine. There was no significant effect of dietary copper on tissue zinc levels. In the zinc-deficient groups, the level of iron was higher in most tissues than in tissues from controls (5 μg Cu, 100 μg Zn/g diet). In the copper-deficient groups, iron concentration was higher than control values only in the liver. These data show that dietary zinc affected tissue copper levels primarily when dietary copper was deficient, that dietary copper had no effect on tissue zinc, and that both zinc deficiency and copper deficiency affected tissue iron levels.     

Effect of dietary protein, zinc, and carbon monoxide on fetal zinc concentration in mice

Dietary protein and zinc deficiencies known to be detrimental to the developing fetus are common in pregnant women in developing countries. Everyone in modern society is at risk of exposure to carbon monoxide (CO). This study was conducted to observe the effect of dietary protein, zinc, and exposure to CO on the fetal zinc concentrations by factorial experimentation. Pregnant mice of CD-1 strain were maintained on 17% (control) or 9% (deficient) protein diets mixed with deficient, normal (control), or supplemental zinc throughout gestation. The dams in each dietary group were exposed to air (control) or 500 ppm CO in air in environmental chambers from gestation day 8 to gestational day 18. The dams were sacrificed on d 18 and fetal zinc levels were measured by atomic absorption spectrophotometry. Carbon monoxide levels used in this study had no significant effect on fetal zinc concentration in any treatment group. When both dietary protein and zinc levels were normal, the mean fetal zinc concentrations were higher than all other dietary protein/zinc combinations (15.2±6.0 and 14.2±4.1 μg Zn/g of tissue for 0 and 500 ppm CO levels). However, when dietary protein levels were deficient, supplemental zinc increased the fetal zinc concentrations significantly (12.7±3.8 and 13.1±0.3.6 μg Zn/g of tissue, in 0 and 500 ppm CO groups) as compared to zinc-deficient groups (8.7±3.0 and 10.0±3.3 μg Zn/g of tissue in 0 and 500 ppm CO groups). The results of this study may be relevant to populations that experience both marginal zinc and protein diets during gestation.     

Effects of essential divalent metals on carcinogenicity and metabolism of nickel and cadmium

Interactions between the physiologically essential metals calcium, magnesium, and zinc and the carcinogenic metals nickel and cadmium were investigated to help elucidate the mechanisms of action of the carcinogenic metals. Bioassay studies revealed several significant findings, including: (1) the ability of magnesium and calcium to inhibit nickel-induced elevation of pulmonary adenoma incidence in strain A mice; (2) the ability of magnesium, but not of calcium, to prevent cadmium-induced subcutaneous sarcoma formation; and (3) the ability of magnesium, but not of calcium, to inhibit nickel-induced muscle tumor formation. Biochemical studies indicated a direct relationship between the antitumorigenic potential of magnesium and the capacity of this metal to: (1) inhibit nickel and cadmium uptake by the target tissues in vivo; (2) inhibit nickel-induced disturbances in DNA synthesis in vivo; (3) inhibit nuclear and cytosolic uptake of nickel by the target tissue cells in vivo; and (4) inhibit nickel and cadmium binding to DNA in vitro. Calcium, which in most cases did not prevent carcinogenesis, had no consistent influence on the uptake of carcinogenic metals or their biochemical effects in the target tissues. Magnesium and zinc, but not calcium, were also found to attenuate the acute toxic effects of nickel, indicating a possible correlation between prevention of acute effects and reduction in tumorigenicity. Zinc, which antagonizes cadmium tumorigenicity in the rat testis, was found to reduce markedly cadmium uptake into isolated testicular interstitial cells. Also, zinc was found to inhibit strongly cadmium binding to DNA in vitro.     

Mercury chloride increases hepatic alanine aminotransferase and glucose 6-phosphatase activities in newborn rats in vivo

This work investigated the in vivo and in vitro effects of HgCl2 and ZnCl2 on metabolic enzymes from tissues of young rats to verify whether the physiological and biochemical alterations induced by mercury and prevented by zinc are related to hepatic and renal glucose metabolism. Wistar rats received (subcutaneous) saline or ZnCl2 (27 mg/kg/day) from 3 to 7 days old and saline or HgCl2 (5.0 mg/kg/day) from 8 to 12 days old. Mercury exposure increased the hepatic alanine aminotransferase (～6-fold) and glucose 6-phosphatase (75%) activity; zinc pre-exposure prevented totally and partially these mercury alterations respectively. In vitro, HgCl2 inhibited the serum (22%, 10 μM) and liver (54%, 100 μM) alanine aminotransferase, serum (53%) and liver (64%) lactate dehydrogenase (10 μM), and liver (53%) and kidney (41%) glucose 6-phosphatase (100 μM) from 10- to 13-day-old rats. The results show that mercury induces distinct alterations in these enzymes when tested in vivo or in vitro as well as when different sources were used. The increase of both hepatic alanine aminotransferase and glucose 6-phosphatase activity suggests that the mercury-exposed rats have increased gluconeogenic activity in the liver. Zinc prevents the in vivo effects on metabolic changes induced by mercury.     

Effects of copper aspirinate and aspirin on tissue copper,zinc, and iron concentrations following chronic oral treatment in the adjuvant arthritic rat

Concentrations of copper, zinc, and iron were analyzed and compared in a number of tissues of adjuvant arthritic rats following 22 d of chronic treatment (per os) with either vehicle, aspirin or copper aspirinate, at doses of 100 mg/kg, 200 mg/kg, or 400 mg/kg. Such chronic treatment resulted in a negative balance in copper, zinc, and iron in many tissues. Among the tissues examined, liver and kidney exhibited the greatest changes in metal concentrations; brain and skeletal muscle exhibited the least. Arthritis-induced changes in the concentrations of all three metals in the liver were reversed upon treatment with aspirin. Treatment with copper aspirinate, on the other hand, resulted in an extremely high accumulation of copper in the liver. Arthritis-induced changes in copper, zinc, and iron concentrations in the pancreas and copper concentration in the plasma were generally not reversed upon treatment with either aspirin or copper aspirinate. Among the three metals examined, the degree of change observed as a result of drug treatments was greatest for iron and least for zinc. Finally, it appeared that the effects of aspirin and copper aspirinate on tissue metal concentrations were independent of the antiarthritic effects of these compounds.     

Interaction between dietary calcium supplementation and chronic waterborne zinc exposure in juvenile rainbow trout, Oncorhynchus mykiss

This study investigated the effects of dietary Ca2+ on branchial Ca2+ and Zn2+ uptake, new and total zinc accumulation in target tissues (gill, liver and kidney), calcium and zinc homeostasis, and acute tolerance to waterborne zinc in fish chronically exposed to waterborne zinc. Juvenile rainbow trout (Oncorhynchus mykiss) were maintained on a calcium-enriched diet [41.2 mg vs. 21.2 mg (control) calcium/g dry wt. of food] and chronic waterborne zinc exposure (2.3 micromol/L), both separately and in combination, for 28 days. Calcium-supplemented diet in the absence of waterborne zinc significantly reduced branchial Ca2+ and Zn2+ influx rates, and new and total zinc accumulations in target tissues relative to control. However it did not protect against the acute zinc challenge. In contrast, waterborne zinc exposure significantly increased branchial Ca2+ and Zn2+ influx rates, new and total zinc concentrations in target tissues, and acute zinc tolerance relative to control. Interestingly, no such changes in any of these parameters were recorded in fish treated simultaneously with elevated dietary Ca2+ and waterborne zinc, except acute zinc tolerance which was highest among all the treatments. Thus, we conclude that the interactions between elevated dietary Ca2+ and waterborne zinc can protect freshwater fish against waterborne zinc toxicity.     

Pycnogenol attenuates the inflammatory and nitrosative stress on joint inflammation induced by urate crystals

Acute gouty arthritis results from monosodium urate (MSU) crystal deposition in joint tissues. Deposited MSU crystals induce an acute inflammatory response which leads to damage of joint tissue. Pycnogenol (PYC), an extract from the bark of Pinus maritime, has documented antiinflammatory and antioxidant properties. The present study aimed to investigate whether PYC had protective effects on MSU-induced inflammatory and nitrosative stress in joint tissues both in vitro and in vivo. MSU crystals upregulated cyclooxygenase 2 (COX-2), interleukin 8 (IL-8) and inducible nitric oxide synthase (iNOS) gene expression in human articular chondrocytes, but only COX-2 and IL-8 in synovial fibroblasts. PYC inhibited the up-regulation of COX-2, and IL-8 in both articular chondrocytes and synovial fibroblasts. PYC attenuated MSU crystal induced iNOS gene expression and NO production in chondrocytes. Activation of NF-κB and SAPK/JNK, ERK1/2 and p38 MAP kinases by MSU crystals in articular chondrocytes and synovial fibroblasts in vitro was attenuated by treatment with PYC. The acute inflammatory cell infiltration and increased expression of COX-2 and iNOS in synovial tissue and articular cartilage following intra-articular injection of MSU crystals in a rat model was inhibited by coadministration of PYC. Collectively, this study demonstrates that PYC may be of value in treatment of MSU crystal-induced arthritis through its anti-inflammatory and anti-nitrosative activities.     

Changes of the Cu and Zn contents in lung and liver in intestinal ischemic reperfusion and general ischemic reperfusion in rabbits

The changes of pulmonary and liver Cu-Zn contents were determined and evaluated in intestinal ischemic reperfusion (IIR) and general ischemic reperfusion (GIR) of rabbits. The contents of pulmonary Zn and liver Cu were found to be lower, and Cu/Zn ratio increased in lung tissue and decreased in liver tissue in IIR. The contents of pulmonary Zn were increased, and the contents of liver Cu were decreased; Cu/Zn ratio also decreased in both tissues in GIR. Pulmonary Cu and liver Zn contents were not changed in IIR and GIR. These results showed that lower or higher Zn in lung tissue and lower Cu in liver tissue were related to the acute tissue injury during IIR and GIR, suggesting that regulating the state of pulmonary Zn and liver Cu should be attempted during the prevention and treatment of both ischemic reperfusions.     

Feeding of a low-zinc diet lowers the tissue concentrations of alpha-tocopherol in adult rats

Previous work has shown that a low dietary intake of zinc for a short duration significantly lowers the lymphatic absorption of α-tocopherol (αTP) in adult male rats. The present study investigated whether the nutritional status of zinc is critical in maintaining the tissue levels of the vitamin. One group of rats was fed an AIN-93G diet containing 3 mg zinc/kg (low zinc, LZ) and the other was fed the same diet but containing 30 mg zinc/kg (adequate zinc, AZ). Food intakes between groups were matched by feeding two meals per day. At 6 wk, the body weights (356±8 g) of LZ rats reached 98% those (362±10 g) of AZ rats. Feeding of the LZ diet for 6 wk significantly lowered the concentrations of both αTP and zinc in the liver, kidney, heart, testis, and brain. No consistent relationships between αTP and zinc concentrations were observed in other tissues such as spleen, lung, gastrocnemius muscle, and retroperitoneal fat tissues. The concentrations of αTP in the liver, testis, brain, spleen, heart, and kidney were significantly correlated with the tissue concentrations of zinc. The LZ diet slightly but significantly increased the total lipid contents (mg/g) of liver, kidney, heart, and spleen. However, the tissue levels of phospholipid (μmol/100 mg lipid) in the heart, lung, testis, and spleen were decreased significantly in LZ rats. These findings indicate that low zinc intake results in a pronounced decrease in the animal’s αTP status under the conditions of matched food intakes, body weights, and feeding patterns. The lower tissue levels of αTP may explain in part the compromised antioxidant defense system and increased susceptibility to oxidative damage observed in zinc deficiency.     

The effect of sodium selenite toxicity on tissue distribution of zinc,iron, and copper in rats

Male Sprague-Dawley rats were used to determine the effects of suptoxic and toxic concentrations of selenite in the drinking water on tissue distribution of zinc (Zn), iron (Fe), and copper (Cu). Se (as sodium selenite) was provided in drinking water at concentrations of 0, 2, 4, and 8 ppm. At 19 d, half of the rats in 4 and 8 ppm Sesupplemented groups were kept on drinking water alone for additional 13 d. All rats were sacrificed at the end of 32 d of experiment. Heart, liver, and kidney were analyzed for the concentrations of Fe, Zn, and Cu by atomic absorption spectrophotometry and of Se by a fluorometric method. Results indicated that rats receiving 4 and 8 ppm Se in drinking water showed a marked reduction in food intake and a reduced growth rate. These adverse effects were quickly reversed when high Se intake was discontinued. Se toxicity caused minimal change in zinc status, reduced tissue iron concentrations and caused a marked increase in copper contents in heart, liver, and kidney. The latter findings were only partly reversed after removal of Se in drinking water. The accumulation of Cu in the tissues of Se-toxic rats provides the evidence of some interaction between Se and Cu.     

Protective effect of zinc on liver injury induced byd-galactosamine in rats

The protective effects of zinc on liver injury induced byd-galactosamine (GalN) were investigated in rats in vivo and in vitro. Zinc supplementation (50 mg/kg/d) for 5 d of rats treated with GalN (1.5 g/kg, ip) could reduce their mortality rate, restore liver pathomorphological changes, maintain zinc content, inhibit the lipid peroxidation, hasten the protein synthesis, and improve liver function. In vitro, zinc supplement could abate the death of GalN-intoxicated hepatocytes, decrease malonaldehyde (MDA) content, and maintain reduced glutathione (GSH). It is concluded that zinc has protective effects on GalN-induced liver damage. Its effects may be owing to inhibition of lipid peroxidation and hastening of protein syntheses.     

Analysis of sensitivity of stromal stem cells (CFU-f) from rat bone marrow and fetal liver to 5-fluorouracil

The sensitivity of stromal stem cells (CFU-f) from rat bone marrow and fetal liver to the cytotoxic effect of 5-fluorouracil (5-FU) was compared in vivo and in vitro. Cells from both tissues demonstrated a similar resistance to 5-FU in vitro; however, stromal stem cells from fetal liver proved notably more sensitive to 5-FU compared to marrow CFU-f in vivo. Cells forming colonies of different size were identified in stem cell populations from both tissues. Cells giving rise to small colonies had a higher resistance to 5-FU both in vivo and in vitro.