Experimental stress-induced changes in trace element levels of various tissues in rats

Hepatic Homeostasis of Metal Ions Following Acute Repeated Stress Exposure in Rats

Essential metals such as copper, iron, and zinc are cofactors in various biological processes including oxygen utilisation, cell growth, and biomolecular synthesis. The homeostasis of these essential metals is carefully controlled through a system of protein transporters involved in the uptake, storage, and secretion. Some metal ions can be transformed by processes including reduction/oxidation (redox) reactions, and correspondingly, the breakdown of metal ion homeostasis can lead to formation of reactive oxygen and nitrogen species. We have previously demonstrated rapid biochemical responses to stress involving alterations in the redox state to generate free radicals and the resultant oxidative stress. However, the effects of stress on redox-active metals including iron and copper and redox-inert zinc have not been well characterised. Therefore, this study aims to examine the changes in these essential metals following exposure to short-term repeated stress, and to further elucidate the alterations in metal homeostasis through expression analysis of different metal transporters. Outbred male Wistar rats were exposed to unrestrained (control), 1 day, or 3 days of 6 h restraint stress (n = 8 per group). After the respective stress treatment, blood and liver samples were collected for the analysis of biometal concentrations and relative gene expression of metal transporter and binding proteins. Exposure to repeated restraint stress was highly effective in causing hepatic redox imbalance. Stress was also shown to induce hepatic metal redistribution, while modulating the mRNA levels of key metal transporters. Overall, this study is the first to characterise the gene expression profile of metal homeostasis following stress and provide insight into the changes occurring prior to the onset of chronic stress conditions.

Effects of chronic light/dark cycle on iron zinc and copper levels in different brain regions of rats

In this study, we aimed to investigate whether chronic shift in light/dark cycle alters brain trace element concentrations. For this purpose, 20 male Wistar albino adult rats were weighed and randomly divided into three groups. The first group (n = 6) was the control and had been subjected to 12/12-h light/dark cycle for 30 days. The second group (n = 7) was subjected to 6/18-h light/dark cycle for 15 days, and the third group (n = 7) was also subjected to 6/18-h light/dark cycle for 15 days and then returned to normal 12/12-h light/dark cycle for 15 days. When light/dark cycle protocols were completed, tissue specimens of the frontal lobe, temporal lobe, and brain stem were collected. Iron (Fe), zinc (Zn), and copper (Cu) concentrations of the frontal lobe, temporal lobe, and brain stem were determined by an atomic absorption spectrophotometer. When compared with controls, Fe levels of the temporal lobe significantly increased in 6/18-h light/dark cycle group (p < 0.05), whereas it was statistically unchanged in rats which were exposed to 6/18-h light/dark cycle then returned to the normal 12/12-h light/dark cycle period. Our results show that chronic shift in light/dark cycle affects trace element concentrations of the brain, especially Fe level in the temporal lobe, and these changes are reversible.

Investigation of lead mobilization from the buckshot residues to the critical organs

Lead exposure causes neurotoxicity, reproductive system dysfunction, renal failure, and blood and endocrine system disorders in human and experimental animals. In this study, we investigated lead mobilization from gunshot fragments to the critical organs (brain, heart, liver, and kidney) and its interaction with essential trace elements on experimental rat model. Thirty-five rats were randomly divided in five groups. The first group was a control and the others were subjected to buckshot implantation in their skeletal muscles (second and third groups) and abdomen (fourth and fifth groups). The control group and the second and fourth groups were sacrificed 1 month after the onset of experiment while the third and fifth groups were followed after 2 months. Blood lead levels were significantly elevated in both 2 month-followed groups and 1 month-followed intraabdominal group. There were significant increases in brain lead levels of both 2 month-followed groups. For the 1 month-followed groups, kidney lead levels were also significantly higher than those of controls. Results show that lead mobilizes from the buckshot residues in distance tissues to the critical organs and interacts with iron, copper, and zinc even though blood lead level sometimes remains unchanged. Our findings are crucial in revealing lead accumulation in critical organs of subjects carrying any gunshot fragments. These subjects and physicians should be in alert for emergence of lead-induced manifestations.

The effect of β-glucan on trace element levels in intra-abdominal sepsis in rats

Sepsis is associated with the development of progressive damage in multiple organ systems. The beneficial effect of glucans has been attributed to modulation of immune function and enhances defense against bacterial, viral, fungal, and parasitic infections. The aim of this study was to investigate the putative protective effect of ß-glucan on changes of trace element levels in various tissues after experimental sepsis in rats. Sepsis was induced by cecal ligation and perforation (CLP) in 28 male Wistar albino rats. To evaluate this, rats were divided into four groups as sham operated, ß-glucan treated sham operated, CLP, and ß-glucan treated CLP. Sixteen hours after operation, rats were decapitated and zinc (Zn) and copper (Cu) levels were determined in the liver, kidney, heart, diaphragm, and lung tissues. The results demonstrate that sepsis significantly decreased zinc and copper levels of all tissues. The decrease in tissue zinc and copper levels demonstrates the role of trace elements in sepsis-induced tissue damage. Our results indicated that ß-glucan administration did not return the zinc and copper levels to the control group level, and it seems likely that the given dose of ß-glucan was insufficient to prevent sepsis-induced organ injury.

Zinc, copper, iron, and selenium levels in brain and liver of mice exposed to acrylonitrile

The mechanism of toxicity of acrylonitrile (AN) has not been fully defined. The research described herein was undertaken to investigate the possible effects of AN on the levels of metallic elements in liver and brain of mice. Thirty-two mice were randomly assigned to four separate groups and treated intraperitoneal (i.p.) once daily for 1 week. Mice in the control group received normal saline, and mice in the three exposure groups received 5, 10, or 20 mg AN/kg b.w. Samples of brain and liver were collected immediately after decapitation. Tissue levels of trace elements (zinc, copper, iron) were determined with flame atomic absorption spectrophotometer or double channel atomic fluorescence absorption spectrophotometer (selenium). Mean brain weights of AN-treated mice were increased as a function of dose compared to controls, but there was no significant change in the ratio of liver/body weight in the four groups. While mean brain zinc decreased as a function of AN dosage, mean liver zinc of the low-dose group significantly increased (p < 0.05); mean liver copper in the medium-dose AN group was significantly higher compared to controls (p < 0.05); however, mean brain copper was increased, but the difference did not attain statistical significance in the three AN groups when compared with the controls (p > 0.05). Mean brain iron levels were significantly decreased in the middle-dose AN group (p < 0.05), but there were no consistent changes in liver iron. Tissue levels of selenium in brain and liver were similar for the control and AN treatment groups. AN induces significant and differential changes in the levels of zinc, copper, and iron in brain and liver. These changes likely play a pivotal role in mediating AN toxicity, most likely via changes in cellular redox status.

Relationships among iron, protein oxidation and lipid peroxidation levels in rats with alcohol-induced acute pancreatitis

It has been previously shown that alcohol induces the damage of pancreatic parenchyma tissue, but the mechanism of this damage is still poorly understood. Assuming that oxygen radical damage may be the involved, we measured markers of oxidative damage in pancreatic tissue, blood serum, plasma, and whole blood of rats with early-stage alcohol-induced acute pancreatitis. Thirty-eight male Wistar rats were divided into three groups: the control group (group 1), the acute pancreatitis group 1 day (group 2), and 3 days (group 3) after the injection of ethyl alcohol into the common biliary duct, respectively. The levels of Fe in tissue and serum, whole blood viscosity, plasma viscosity, fibrinogen and homocysteine (Hcy) levels, erythrocyte and plasma malondialdehyde (MDA), and tissue and plasma protein carbonyl levels were found to be significantly higher in groups 2 and 3 than in group 1. However, the levels of reduced glutathione (GSH) in tissue and erythrocytes were significantly lower in groups 2 and 3 than in group 1. These results suggest that elevated Fe levels in serum and pancreatic tissue in rats with early-stage alcohol-induced acute pancreatitis is associated with various hemorheological changes and with oxidative damage of the pancreas.